error installing psycopg2, library not found for -lssl

error installing psycopg2, library not found for -lssl - python

I run
sudo pip install psycopg2
and I get a bunch of output that looks like:
cc -DNDEBUG -g -fwrapv -Os .....
.....
cc -DNDEBUG -g -fwrapv -Os .....
.....
And at the end it says:
ld: library not found for -lssl
clang: error: linker command failed with exit code 1 (use -v to see invocation)
error: command 'cc' failed with exit status 1
----------------------------------------
Cleaning up...
Command /usr/bin/python -c "import setuptools, tokenize;__file__='/private/var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip_build_root/psycopg2/setup.py';exec(compile(getattr(tokenize, 'open', open)(__file__).read().replace('\r\n', '\n'), __file__, 'exec'))" install --record /var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip-uE3thn-record/install-record.txt --single-version-externally-managed --compile failed with error code 1 in /private/var/folders/bz/pvj1g9xj16d10pjjgbrfl3fw0000gn/T/pip_build_root/psycopg2
Storing debug log for failure in /Users/Tyler/Library/Logs/pip.log
Running easy_install or doing it from source both give me the same error at the end (the part about library not found for -lssl).
Running brew install (or upgrade) openssl yields the below
$ brew upgrade openssl
Error: openssl-1.0.1h already installed
Can anyone help me out?

For anyone looking for a solution for this on macOS Sierra 10.12 (or later, most likely): I fixed this by installing the command line tools:
xcode-select --install
After that, pip install psycopg2 should work.
If it doesn't, you could also try to link against brew's openssl:
env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip install psycopg2
with openssl installed via brew. Note that the brew link openssl --force does not work anymore:
$ brew link openssl --force 17.5s
Warning: Refusing to link: openssl
Linking keg-only openssl means you may end up linking against the insecure,
deprecated system OpenSSL while using the headers from Homebrew's openssl.
Instead, pass the full include/library paths to your compiler e.g.:
-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib
As #macho points out below if this still does not work, you might need to use the --no-cache option of pip, e.g.
env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip --no-cache install psycopg2
Remember to adjust these paths accordingly should you for instance build on ARM/Apple M1 Macs (as homebrew is installed at /opt/homebrew/); command as follows:
env LDFLAGS="-I/opt/homebrew/opt/openssl/include -L/opt/homebrew/opt/openssl/lib" pip --no-cache install psycopg2

If you have OpenSSL installed from brew (brew install openssl)
The following works:
export LDFLAGS="-L/usr/local/opt/openssl/lib"
export CPPFLAGS="-I/usr/local/opt/openssl/include"
pip install psycopg2

Using brew link openssl is dangerous as it might mess up your system by symlinking Homebrew's OpenSSL headers while the actual libraries will remain the system-supplied ones, causing all kinds of issues. Homebrew actually warns you against this if you try (and other answers suggest linking won't solve the problem anymore anyway):
$ brew link openssl
Warning: Refusing to link: openssl
Linking keg-only openssl means you may end up linking against the insecure,
deprecated system OpenSSL while using the headers from Homebrew's openssl.
Instead, pass the full include/library paths to your compiler e.g.:
-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib
Following this advice here's the pip command you need to use:
$ pip install -r requirements.txt --global-option=build_ext --global-option="-I/usr/local/opt/openssl/include" --global-option="-L/usr/local/opt/openssl/lib"
For pipenv, I am not aware of any command-line attributes you can pass to it, however you can export the aforementioned paths as environment variables prior to running pipenv install:
$ export LDFLAGS="-L/usr/local/opt/openssl/lib" export CPPFLAGS="-I/usr/local/opt/openssl/include"
$ pipenv install

With MacOS Catalina 10.15.4, the following was the only command that worked for me:
env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip install psycopg2

Solution for MacOS 12 Monterey - M1 Chipset:
xcode-select --install
brew install openssl
echo 'export PATH="/opt/homebrew/opt/openssl#3/bin:$PATH"' >> ~/.zshrc
echo 'export LIBRARY_PATH=$LIBRARY_PATH:/opt/homebrew/opt/openssl#3/lib/' >> ~/.zshrc

Solution for MacOS BigSur (May 2021)
I was having a similar issue.
But just befor kicking my pc of the desk I found a solution, that worked for me on MacOS BigSur:
My OpenSSL installation was corrupted.
brew reinstall openssl
After the reinstallation is completed it will spit out 3 commands you need to execute:
The commands will look like this:
DONT JUST COPY
echo 'export PATH="/opt/homebrew/opt/openssl#1.1/bin:$PATH"' >> ~/.zshrc
export LDFLAGS="-L/opt/homebrew/opt/openssl#1.1/lib"
export CPPFLAGS="-I/opt/homebrew/opt/openssl#1.1/include"
This worked for me! There is no guarantee that this will work for you too.
brew reinstall might not be the best solution, but it worked and provided the necessary commands.

What worked for me was the hint provided in the command to link openssl,
$ brew link openssl
Warning: Refusing to link macOS-provided software: openssl
If you need to have openssl first in your PATH run:
echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.zshrc
For compilers to find openssl you may need to set:
export LDFLAGS="-L/usr/local/opt/openssl/lib"
export CPPFLAGS="-I/usr/local/opt/openssl/include"
$ export LDFLAGS="-L/usr/local/opt/openssl/lib"
$ export CPPFLAGS="-I/usr/local/opt/openssl/include"
$ pip install psycopg2
Collecting psycopg2
Using cached https://files.pythonhosted.org/packages/23/7e/93c325482c328619870b6cd09370f6dbe1148283daca65115cd63642e60f/psycopg2-2.8.2.tar.gz
Installing collected packages: psycopg2
Running setup.py install for psycopg2 ... done
Successfully installed psycopg2-2.8.2

On mojave I added these to the .bash_profile
export PATH="/usr/local/opt/openssl/bin:$PATH"
export LDFLAGS="-L/usr/local/opt/curl/lib -L/usr/local/opt/openssl/lib"
export CPPFLAGS="-I/usr/local/opt/curl/include -I/user/local/opt/openssl/include"
was then able to install psycopg 2.8.3 in a python 3.7.4 virtualenv.
This after reinstalling xcode and the command line tools.
All the answers above helped!

This's the problem of new macOs version, where pip cannot install cryptography. What fixed my problem is to provide the env to the install command:
brew install openssl
env LDFLAGS="-L$(brew --prefix openssl)/lib" CFLAGS="-I$(brew --prefix openssl)/include" <YOUR COMMAND HERE>
You can replace <YOUR COMMAND HERE> with pip install cryptography, or pip install <SOMETHING THAT REQUIRES cryptography> for example.
Credit to this article: Fixing macOS Sierra fatal error: 'openssl/opensslv.h' or 'openssl/aes.h' file not found

export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/opt/openssl/lib/
worked for me

Using Fish, the following two commands solved this issue for me after installing OpenSSL with Homebrew.
set -gx LDFLAGS "-L/usr/local/opt/openssl/lib"
set -gx CPPFLAGS "-I/usr/local/opt/openssl/include"
Use brew info openssl to get up-to-date info.

If the export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/opt/openssl/lib/ command doesn't change anything for you, then you may also need to specify openssl version in this path like
export LIBRARY_PATH=$LIBRARY_PATH:/usr/local/opt/openssl#1.1/lib/
Note the #1.1 after openssl.

If you:
Are trying to install psycopg2 inside of a Python venv AND
Are trying to install psycopg2 on Apple Silicon (new ARM CPUs)
Then, as IamAshay directed in their answer, we need to export some variables to point to our OpenSSL installation.
The install directory on Apple Silicon is apparently different ofrom Apple Intel machines. Regardless, to find where OpenSSL is installed (via homebrew) on your system, you can run
brew --prefix openssl
In my case, we have /opt/homebrew/opt/openssl#1.1. So this means that the variables we need to export would be
export LDFLAGS="-L/opt/homebrew/opt/openssl/lib"
export CPPFLAGS="-I/opt/homebrew/opt/openssl/include"
Then we can run
pip install psycopg2

Instead of installing psycopg2, install psycopg2-binary, from the same authors:
pip install psycopg2-binary
This is what the documentation says about this PyPI package:
You can [...] obtain a stand-alone package, not requiring a compiler or external libraries, by installing the psycopg2-binary package from PyPI:
$ pip install psycopg2-binary
The binary package is a practical choice for development and testing but in production it is advised to use the package built from sources.

Recently had this problem in High Sierra, having just installed Python 3.7 in a virtualenv.
The solution is to use a later version of psycopg2. Version 2.7.7 worked, where 2.7.1 did not.

I installed OpenSSL using MacPorts therefore directories are not like those of Brew.
sudo port install openssl
I found the directories by doing:
port contents openssl | grep lib
port contents openssl | grep include
Then I exported the variables:
export LDFLAGS="-L/opt/local/lib"
export CPPFLAGS="-I/opt/local/include/openssl"
You might also have to:
xcode-select --install

If using homebrew, it may not be the best idea to force link openssl. As some above answers outlined, the following worked for me inside a venv:
export LDFLAGS="-L/opt/homebrew/opt/openssl#1.1/lib"
export CPPFLAGS="-I/opt/homebrew/opt/openssl#1.1/include"
pip install psycopg2

I was having this issue on Mojave. Mojave does not create a /usr/include directory, which psycopg2 needs to install. This was not obvious. I found the solution here:
How to update Xcode from command line, which references:
https://forums.developer.apple.com/thread/104296

I had this same error and got it to resolve after I pip installed cython

Running PyCharm from conda environment, solved my issue using:
--> conda install psycopg2
The following packages will be UPDATED: ...
...
Proceed ([y]/n)?
--> y
--> pip3 install psycopg2
Installing collected packages: psycopg2
Running setup.py install for psycopg2 ... done
Successfully installed psycopg2-2.8.4
'''

I know you are asking for development environment but if you are deploying on server say, Heroku. Just add below line in the requirements.txt of your project.
django-heroku==0.3.1
As this package itself will install the required packages like psycopg2 on server deployment. So let heroku server handle this.

In my case, openssl is located inside homebrew directory and suggested answers don't work.
Bad:
LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib"
Good:
LDFLAGS="-I/opt/homebrew/Cellar/openssl#1.1/1.1.1i/include -L/opt/homebrew/Cellar/openssl#1.1/1.1.1i/lib" pip install psycopg2
Tip:
You can easily find homebrew's openssl directory using brew --prefix openssl. Make sure to include version folder (1.1.1i in my case).

I tried most of the other answers here without success. The only thing that worked for me was updating from psycopg2 from 2.8 to 2.9.2 (running MacOS 12 with Apple M1)

Tried everything listed here, then switched shell from zsh to bash, then it worked.

I've managed to fix it by using:
brew unlink openssl && brew link openssl --force
I am not sure how this differs from the brew uninstall/upgrades that I did on OpenSSL in prior attempts I've made. My assumption is that these operations left some of the "faulty" shared libraries which were preventing this from working. Note that this also fixed issues with installing python cryptography module.

Related

Python get-pip.py fails due to site-package not writtable and SSL not available while they seem OK [duplicate]

I've install Python 3.4 and Python 3.6 on my local machine successfully, but am unable to install packages with pip3.
When I execute pip3 install <package>, I get the following SSL related error:
pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Collecting <package>
Could not fetch URL https://pypi.python.org/simple/<package>/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
Could not find a version that satisfies the requirement <package> (from versions: )
No matching distribution found for <package>
How can I fix my Python3.x install so that I can install packages with pip install <package>?

Step by step guide to install Python 3.6 and pip3 in Ubuntu
Install the necessary packages for Python and ssl: $ sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
Download and unzip "Python-3.6.8.tar.xz" from https://www.python.org/ftp/python/ into your home directory.
Open terminal in that directory and run: $ ./configure
Build and install: $ make && sudo make install
Install packages with: $ pip3 install package_name
Disclaimer: The above commands are not tested in Ubuntu 20.04 LTS.

If you are on Windows and use anaconda this worked for me:
I tried a lot of other solutions which did not work (Environment PATH Variable changes ...)
The problem can be caused by DLLs in the Windows\System32 folder (e.g. libcrypto-1_1-x64.dll or libssl-1_1-x64.dll or others) placed there by other software.
The fix was installing openSSL from https://slproweb.com/products/Win32OpenSSL.html which replaces the dlls by more recent versions.

If you are on Red Hat/CentOS:
# To allow for building python ssl libs
yum install openssl-devel
# Download the source of *any* python version
cd /usr/src
wget https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
tar xf Python-3.6.2.tar.xz
cd Python-3.6.2
# Configure the build w/ your installed libraries
./configure
# Install into /usr/local/bin/python3.6, don't overwrite global python bin
make altinstall

I had a similar problem on OSX 10.11 due to installing memcached which installed python 3.7 on top of 3.6.
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Spent hours on unlinking openssl, reinstalling, changing paths.. and nothing helped. Changing openssl version back from to older version did the trick:
brew switch openssl 1.0.2e
I did not see this suggestion anywhere in internet. Hope it serves someone.

In Ubuntu, this can help:
cd Python-3.6.2
./configure --with-ssl
make
sudo make install

Agree with the answer by mastaBlasta. Worked for me. I encountered the same problem as the topic description.
Environment: MacOS Sierra. And I use Homebrew.
My solution:
Reinstall openssl by brew uninstall openssl; brew install openssl
According to the hints given by Homebrew, do the following:
echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile
export LDFLAGS="-L/usr/local/opt/openssl/lib"
export CPPFLAGS="-I/usr/local/opt/openssl/include"

I had the same issue with python3.8.5 installation on Debian9. I have done a build, but when I have tried to download some modules, pip3.8 issued following error:
pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
I have searched for the root of my problem and found out that there is a system dependent portion of the python build which is called by system independent one. In case of missing ssl you just needed to open python terminal and check whether is _ssl present:
>>> help('modules')
.
.
_sre enum pwd wave
_ssl errno py_compile weakref
_stat faulthandler pyclbr webbrowser
.
.
If not your system dependent ssl module part is missing. You can check it also by listing content of <python_installation_root>/lib/python3.8/lib-dynload:
>ls ./lib/python3.8/lib-dynload | grep ssl
_ssl.cpython-38-x86_64-linux-gnu.so
The problem was caused as written by PengShaw by missing libssl-dev during the build. Therefore you have to follow the recommended python installation flow. First install prerequisites and then build and install the python. Installation without devel versions of libs resulted in my case in the missing system dependent part. In this case _ssl.
Note that the devel lib name differs for Debian and CentOS, therefore check whether the installation hints posted on net are suitable for your specific Linux system type:
For Debian:
sudo apt install -y libbz2-dev libffi-dev libssl-dev
./configure --enable-optimizations
make
make altinstall
For CentOS:
sudo yum -y install bzip2-devel libffi-devel openssl-devel
./configure --enable-optimizations
make
make altinstall
It is for sure a good idea to list configuration options prior the configuration and evtl. use some additional options:
./configure --help
Last but not least in case you use --prefix for a non-default installation location, remember to add your <python_installation_root>/lib to your LD_LIBRARY_PATH .

If you are on Windows and use Anaconda you can try running "pip install ..." command in Anaconda Prompt instead of cmd.exe, as user willliu1995 suggests here. This was the fastest solution for me, that does not require installation of additional components.

The problem probably caused by library missing.
Before you install python 3.6, make sure you install all the libraries required for python.
$ sudo apt-get install build-essential checkinstall
$ sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
More information in How to Install Python 3.6.0 on Ubuntu & LinuxMint

If you are on OSX and have compiled python from source:
Install openssl using brew brew install openssl
Make sure to follow the instructions brew gives you about setting your CPPFLAGS and LDFLAGS. In my case I am using the openssl#1.1 brew formula and I need these 3 settings for the python build process to correctly link to my SSL library:
export LDFLAGS="-L/usr/local/opt/openssl#1.1/lib"
export CPPFLAGS="-I/usr/local/opt/openssl#1.1/include"
export PKG_CONFIG_PATH="/usr/local/opt/openssl#1.1/lib/pkgconfig"
Assuming the library is installed at that location.

Downgrading openssl worked for me,
brew switch openssl 1.0.2s

I encountered the same problem on windows 10. My very specific issue is due to my installation of Anaconda. I installed Anaconda and under the path Path/to/Anaconda3/, there comes the python.exe. Thus, I didn't install python at all because Anaconda includes python. When using pip to install packages, I found the same error report, pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available..
The solution was the following:
1) you can download python again on the official website;
2) Navigate to the directory where "Python 3.7 (64-bit).lnk"is located
3) import ssl and exit()
4) type in cmd, "Python 3.7 (64-bit).lnk" -m pip install tensorflow for instance.
Here, you're all set.

I tried A LOT of ways to solve this problem and none solved. I'm currently on Windows 10.
The only thing that worked was:
Uninstall Anaconda
Uninstall Python (i was using version 3.7.3)
Install Python again (remember to check the option to automatically add to PATH)
Then I've downloaded all the libs I needed using PIP... and worked!
Don't know why, or if the problem was somehow related to Anaconda.

for osx brew users
my issue appeared related to my python installation and was quickly resolved by re-installing python3 and pip. i think it started misbehaving after an OS update but who knows (at this time I am on Mac OS 10.14.6)
brew reinstall python3 --force
# setup pip
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3 get-pip.py
# installa pkg successfully
pip install pandas

You can do either of these two:
While installing Anaconda, select the option to add Anaconda to the path.
or
Find these (complete) paths from your installation folder of Anaconda and add them to the environment variable :
\Anaconda
\Anaconda\Library\mingw-w64\bin
\Anaconda\Library\usr\bin
\Anaconda\Library\bin
\Anaconda\Scripts
\anaconda\Library
\anaconda\condabin
Add the above paths to the "Path" system variable and it should show the error no more :)

The ssl module is a TLS/SSL wrapper for accessing Operation Sytem (OS) socket (Lib/ssl.py). So when ssl module is not available, chances are that you either don't have OS OpenSSL libraries installed, or those libraries were not found when you install Python. Let assume it is a later case (aka: you already have OpenSSL installed, but they are not correctly linked when installing Python).
I will also assume you are installing from source. If you are installing from binary (ie: Window .exe file), or package (Mac .dmg, or Ubuntu apt), there is not much you can do with the installing process.
During the step of configuring your python installation, you need to specify where the OS OpenSSL will be used for linking:
# python 3.8 beta
./configure --with-openssl="your_OpenSSL root"
So where will you find your installed OpenSSL directory?
# ubuntu
locate ssl.h | grep '/openssl/ssl.h'
/home/user/.linuxbrew/Cellar/openssl/1.0.2r/include/openssl/ssl.h
/home/user/envs/py37/include/openssl/ssl.h
/home/user/miniconda3/envs/py38b3/include/openssl/ssl.h
/home/user/miniconda3/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.0.2s-h7b6447c_0/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.1.1b-h7b6447c_1/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.1.1c-h7b6447c_1/include/openssl/ssl.h
/usr/include/openssl/ssl.h
Your system may be different than mine, but as you see here I have many different installed openssl libraries. As the time of this writing, python 3.8 expects openssl 1.0.2 or 1.1:
Python requires an OpenSSL 1.0.2 or 1.1 compatible libssl with X509_VERIFY_PARAM_set1_host().
So you would need to verify which of those installed libraries that you can use for linking, for example
/usr/bin/openssl version
OpenSSL 1.0.2g 1 Mar 2016
./configure --with-openssl="/usr"
make && make install
You may need to try a few, or install a new, to find the library that would work for your Python and your OS.

I was having the same issue and was able to resolve with the following steps:
sudo yum install -y libffi-devel
sudo yum install openssl-devel
cd /usr/src
sudo wget https://www.python.org/ftp/python/3.7.1/Python-3.7.1.tar.xz
sudo tar xf Python-3.7.1.tar.xz
cd Python-3.7.1
sudo ./configure --enable-optimizations
# Install into /usr/local/bin/python3.7, don't overwrite global python bin
sudo make altinstall
depending on perms, you may not need sudo.
Results:
Collecting setuptools
Collecting pip
Installing collected packages: setuptools, pip
Successfully installed pip-10.0.1 setuptools-39.0.1
should now be able to run
python3.7 -V
and
pip3.7 -V
When installing packages:
pip3.7 install pandas
or depending on perms, you can also add the --user flag like so:
pip3.7 install pandas --user

In my case with using Mac, I deleted
/Applications/Python 3.7.
because I already had Python3.7 by brew install python3 .
But it was a trigger of the message
pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
What I did in my situation
I downloaded macOS 64-bit installer again, and installed.
Double click /Applications/Python3.6/Install Certificates.command and /Applications/Python3.6/Update Shell Profile.command.
Reboot mac
And I am not sure but possibly contributed to succeed is pip.conf. See pip install fails.

I finally solve this issue. These are the detail of my env:
Version of Python to install: 3.6.8
OS: Ubuntu 16.04.6 LTS
Root access: No
Some people suggest to install libssl-dev, but it did not work for me. I follow this link and I fixed it!
In short, I download, extract, build, and install OpenSSL (openssl-1.1.1b.tar.gz). Then, I modify .bashrc file follow this link.
Next, I download and extract Python-3.6.8.tgz. I edit Modules/Setup.dist to modify SSL path (lines around #211). I did ./configure --prefix=$HOME/opt/python-3.6.8, make and make install. Last, I modify my .bashrc. Notice that I do not include --enable-optimizations in ./configure.

I was able to fix this by updating the python version in this file.
pyenv: version `3.6.5' is not installed (set by /Users/taruntarun/.python-version)
Though i had the latest version installed, my command was still using old version 3.6.5
Moving to version 3.7.3

Termux
This worked because i didnt have an existing openssl version installed.
pkg install openssl-tool

If you are on OSX and in case the other solutions didn't work for you (just like me).
You can try uninstalling python3 and upgrade pip3
brew uninstall --ignore-dependencies python3
pip3 install --upgrade pip
This worked for me ;)

(NOT on Windows!)
This made me tear my hair out for a week, so I hope this will help someone
I tried everything short of re-installing Anaconda and/or Jupyter.
Setup
AWS Linux
Manually installed Anaconda 3-5.3.0
Python3 (3.7) was running inside anaconda (ie, ./anaconda3/bin/python)
there was also /usr/bin/python and /usr/bin/python3 (but these were not being used as most of the work was done in Jupyter's terminal)
Fix
In Jupyter's terminal:
cp /usr/lib64/libssl.so.10 ./anaconda3/lib/libssl.so.1.0.0
cp /usr/lib64/libcrypto.so.10 ./anaconda3/lib/libcrypto.so.1.0.0
What triggered this?
So, this was all working until I tried to do a conda install conda-forge
I'm not sure what happened, but conda must have updated openssl on the box (I'm guessing) so after this, everything broke.
Basically, unknown to me, conda had updated openssl, but somehow deleted the old libraries and replaced it with libssl.so.1.1 and libcrypto.so.1.1.
Python3, I guess, was compiled to look for libssl.so.1.0.0
In the end, the key to diagnosis was this:
python -c "import ssl; print (ssl.OPENSSL_VERSION)"
gave the clue library "libssl.so.1.0.0" not found
The huge assumption I made is that the yum version of ssl is the same as the conda version, so just renaming the shared object might work, and it did.
My other solution was to re-compile python, re-install anaconda, etc, but in the end I'm glad I didn't need to.
Hope this helps you guys out.

In the case of using pyenv to manage python installations on Mac OS Catalina, I had to install openssl with brew first and then after that run pyenv install 3.7.8 which seemed to build the python installation using the openssl from homebrew (it even said as such in the installation output). Then pyenv global 3.7.8 and I was away.

On macos, configure python 3.8.1 with the command below will solve the problem, i think it would also work on Linux.
./configure --enable-optimizations --with-openssl=/usr/local/opt/openssl#1.1/
change the dir parameter based on your system.

I've made some PATH changes to mimic part of the Anaconda Powershell Prompt $env:PATH
C:\Users\merheb\Miniconda3;C:\Users\merheb\Miniconda3\Library\mingw-w64\bin;C:\Users\merheb\Miniconda3\Library\usr\bin;C:\Users\merheb\Miniconda3\Library\bin;C:\Users\merheb\Miniconda3\Scripts;C:\Users\merheb\Miniconda3\bin;C:\Users\merheb\Miniconda3\condabin;
And It worked for me.

Building from source was what worked for me on Ubuntu 22.10:
Install OpenSSL manually, tested here with OpenSSL 1.1.1s, extracted then ran:
./config --prefix='/opt/openssl' --openssldir='/opt/ssl'
make
make install
Then with your older Python 3 version (here Python-3.8.16) run:
export LD_RUN_PATH='/opt/openssl/lib'
export CC='gcc-12' # sudo apt install gcc-12
./configure --enable-optimizations \
--with-openssl='/opt/openssl' \
--prefix='/opt/python/3.8' -C
make
make install
Test with:
/opt/python/3.8/bin/python3 -c 'import ssl; print(ssl.OPENSSL_VERSION)'
OpenSSL 1.1.1s 1 Nov 2022

The python documentation is actually very clear, and following the instructions did the job whereas other answers I found here were not fixing this issue.
first, install python 3.x.x from source using, for example with version 3.6.2 https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
make sure you have openssl installed by running brew install openssl
unzip it and move to the python directory: tar xvzf Python-3.6.2.tar.xz && cd Python-3.6.2
then if the python version is < 3.7, run
CPPFLAGS="-I$(brew --prefix openssl)/include" \
LDFLAGS="-L$(brew --prefix openssl)/lib" \
./configure --with-pydebug
5. finallly, run make -s -j2 (-s is the silent flag, -j2 tells your machine to use 2 jobs)

I had the same issue trying to install python3.7 on an ubuntu14.04 machine.
The issue was that I had some custom folders in my PKG_CONFIG_PATH and in my LD_LIBRARY_PATH, which prevented the python build process to find the system openssl libraries.
so try to clear them and see what happens:
export PKG_CONFIG_PATH=""
export LD_LIBRARY_PATH=""

Ok the latest answer to this, as of now don't use Python 3.8, use only 3.7 or less , because of most of the libraries fail to install with the above error

Problems with Python installing anything [duplicate]

I've install Python 3.4 and Python 3.6 on my local machine successfully, but am unable to install packages with pip3.
When I execute pip3 install <package>, I get the following SSL related error:
pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Collecting <package>
Could not fetch URL https://pypi.python.org/simple/<package>/: There was a problem confirming the ssl certificate: Can't connect to HTTPS URL because the SSL module is not available. - skipping
Could not find a version that satisfies the requirement <package> (from versions: )
No matching distribution found for <package>
How can I fix my Python3.x install so that I can install packages with pip install <package>?

Step by step guide to install Python 3.6 and pip3 in Ubuntu
Install the necessary packages for Python and ssl: $ sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
Download and unzip "Python-3.6.8.tar.xz" from https://www.python.org/ftp/python/ into your home directory.
Open terminal in that directory and run: $ ./configure
Build and install: $ make && sudo make install
Install packages with: $ pip3 install package_name
Disclaimer: The above commands are not tested in Ubuntu 20.04 LTS.

If you are on Windows and use anaconda this worked for me:
I tried a lot of other solutions which did not work (Environment PATH Variable changes ...)
The problem can be caused by DLLs in the Windows\System32 folder (e.g. libcrypto-1_1-x64.dll or libssl-1_1-x64.dll or others) placed there by other software.
The fix was installing openSSL from https://slproweb.com/products/Win32OpenSSL.html which replaces the dlls by more recent versions.

If you are on Red Hat/CentOS:
# To allow for building python ssl libs
yum install openssl-devel
# Download the source of *any* python version
cd /usr/src
wget https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
tar xf Python-3.6.2.tar.xz
cd Python-3.6.2
# Configure the build w/ your installed libraries
./configure
# Install into /usr/local/bin/python3.6, don't overwrite global python bin
make altinstall

I had a similar problem on OSX 10.11 due to installing memcached which installed python 3.7 on top of 3.6.
WARNING: pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
Spent hours on unlinking openssl, reinstalling, changing paths.. and nothing helped. Changing openssl version back from to older version did the trick:
brew switch openssl 1.0.2e
I did not see this suggestion anywhere in internet. Hope it serves someone.

In Ubuntu, this can help:
cd Python-3.6.2
./configure --with-ssl
make
sudo make install

Agree with the answer by mastaBlasta. Worked for me. I encountered the same problem as the topic description.
Environment: MacOS Sierra. And I use Homebrew.
My solution:
Reinstall openssl by brew uninstall openssl; brew install openssl
According to the hints given by Homebrew, do the following:
echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile
export LDFLAGS="-L/usr/local/opt/openssl/lib"
export CPPFLAGS="-I/usr/local/opt/openssl/include"

If you are on Windows and use Anaconda you can try running "pip install ..." command in Anaconda Prompt instead of cmd.exe, as user willliu1995 suggests here. This was the fastest solution for me, that does not require installation of additional components.

The problem probably caused by library missing.
Before you install python 3.6, make sure you install all the libraries required for python.
$ sudo apt-get install build-essential checkinstall
$ sudo apt-get install libreadline-gplv2-dev libncursesw5-dev libssl-dev libsqlite3-dev tk-dev libgdbm-dev libc6-dev libbz2-dev
More information in How to Install Python 3.6.0 on Ubuntu & LinuxMint

If you are on OSX and have compiled python from source:
Install openssl using brew brew install openssl
Make sure to follow the instructions brew gives you about setting your CPPFLAGS and LDFLAGS. In my case I am using the openssl#1.1 brew formula and I need these 3 settings for the python build process to correctly link to my SSL library:
export LDFLAGS="-L/usr/local/opt/openssl#1.1/lib"
export CPPFLAGS="-I/usr/local/opt/openssl#1.1/include"
export PKG_CONFIG_PATH="/usr/local/opt/openssl#1.1/lib/pkgconfig"
Assuming the library is installed at that location.

Downgrading openssl worked for me,
brew switch openssl 1.0.2s

I encountered the same problem on windows 10. My very specific issue is due to my installation of Anaconda. I installed Anaconda and under the path Path/to/Anaconda3/, there comes the python.exe. Thus, I didn't install python at all because Anaconda includes python. When using pip to install packages, I found the same error report, pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available..
The solution was the following:
1) you can download python again on the official website;
2) Navigate to the directory where "Python 3.7 (64-bit).lnk"is located
3) import ssl and exit()
4) type in cmd, "Python 3.7 (64-bit).lnk" -m pip install tensorflow for instance.
Here, you're all set.

I tried A LOT of ways to solve this problem and none solved. I'm currently on Windows 10.
The only thing that worked was:
Uninstall Anaconda
Uninstall Python (i was using version 3.7.3)
Install Python again (remember to check the option to automatically add to PATH)
Then I've downloaded all the libs I needed using PIP... and worked!
Don't know why, or if the problem was somehow related to Anaconda.

for osx brew users
my issue appeared related to my python installation and was quickly resolved by re-installing python3 and pip. i think it started misbehaving after an OS update but who knows (at this time I am on Mac OS 10.14.6)
brew reinstall python3 --force
# setup pip
curl https://bootstrap.pypa.io/get-pip.py -o get-pip.py
python3 get-pip.py
# installa pkg successfully
pip install pandas

You can do either of these two:
While installing Anaconda, select the option to add Anaconda to the path.
or
Find these (complete) paths from your installation folder of Anaconda and add them to the environment variable :
\Anaconda
\Anaconda\Library\mingw-w64\bin
\Anaconda\Library\usr\bin
\Anaconda\Library\bin
\Anaconda\Scripts
\anaconda\Library
\anaconda\condabin
Add the above paths to the "Path" system variable and it should show the error no more :)

The ssl module is a TLS/SSL wrapper for accessing Operation Sytem (OS) socket (Lib/ssl.py). So when ssl module is not available, chances are that you either don't have OS OpenSSL libraries installed, or those libraries were not found when you install Python. Let assume it is a later case (aka: you already have OpenSSL installed, but they are not correctly linked when installing Python).
I will also assume you are installing from source. If you are installing from binary (ie: Window .exe file), or package (Mac .dmg, or Ubuntu apt), there is not much you can do with the installing process.
During the step of configuring your python installation, you need to specify where the OS OpenSSL will be used for linking:
# python 3.8 beta
./configure --with-openssl="your_OpenSSL root"
So where will you find your installed OpenSSL directory?
# ubuntu
locate ssl.h | grep '/openssl/ssl.h'
/home/user/.linuxbrew/Cellar/openssl/1.0.2r/include/openssl/ssl.h
/home/user/envs/py37/include/openssl/ssl.h
/home/user/miniconda3/envs/py38b3/include/openssl/ssl.h
/home/user/miniconda3/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.0.2s-h7b6447c_0/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.1.1b-h7b6447c_1/include/openssl/ssl.h
/home/user/miniconda3/pkgs/openssl-1.1.1c-h7b6447c_1/include/openssl/ssl.h
/usr/include/openssl/ssl.h
Your system may be different than mine, but as you see here I have many different installed openssl libraries. As the time of this writing, python 3.8 expects openssl 1.0.2 or 1.1:
Python requires an OpenSSL 1.0.2 or 1.1 compatible libssl with X509_VERIFY_PARAM_set1_host().
So you would need to verify which of those installed libraries that you can use for linking, for example
/usr/bin/openssl version
OpenSSL 1.0.2g 1 Mar 2016
./configure --with-openssl="/usr"
make && make install
You may need to try a few, or install a new, to find the library that would work for your Python and your OS.

I was having the same issue and was able to resolve with the following steps:
sudo yum install -y libffi-devel
sudo yum install openssl-devel
cd /usr/src
sudo wget https://www.python.org/ftp/python/3.7.1/Python-3.7.1.tar.xz
sudo tar xf Python-3.7.1.tar.xz
cd Python-3.7.1
sudo ./configure --enable-optimizations
# Install into /usr/local/bin/python3.7, don't overwrite global python bin
sudo make altinstall
depending on perms, you may not need sudo.
Results:
Collecting setuptools
Collecting pip
Installing collected packages: setuptools, pip
Successfully installed pip-10.0.1 setuptools-39.0.1
should now be able to run
python3.7 -V
and
pip3.7 -V
When installing packages:
pip3.7 install pandas
or depending on perms, you can also add the --user flag like so:
pip3.7 install pandas --user

In my case with using Mac, I deleted
/Applications/Python 3.7.
because I already had Python3.7 by brew install python3 .
But it was a trigger of the message
pip is configured with locations that require TLS/SSL, however the ssl module in Python is not available.
What I did in my situation
I downloaded macOS 64-bit installer again, and installed.
Double click /Applications/Python3.6/Install Certificates.command and /Applications/Python3.6/Update Shell Profile.command.
Reboot mac
And I am not sure but possibly contributed to succeed is pip.conf. See pip install fails.

I finally solve this issue. These are the detail of my env:
Version of Python to install: 3.6.8
OS: Ubuntu 16.04.6 LTS
Root access: No
Some people suggest to install libssl-dev, but it did not work for me. I follow this link and I fixed it!
In short, I download, extract, build, and install OpenSSL (openssl-1.1.1b.tar.gz). Then, I modify .bashrc file follow this link.
Next, I download and extract Python-3.6.8.tgz. I edit Modules/Setup.dist to modify SSL path (lines around #211). I did ./configure --prefix=$HOME/opt/python-3.6.8, make and make install. Last, I modify my .bashrc. Notice that I do not include --enable-optimizations in ./configure.

I was able to fix this by updating the python version in this file.
pyenv: version `3.6.5' is not installed (set by /Users/taruntarun/.python-version)
Though i had the latest version installed, my command was still using old version 3.6.5
Moving to version 3.7.3

Termux
This worked because i didnt have an existing openssl version installed.
pkg install openssl-tool

If you are on OSX and in case the other solutions didn't work for you (just like me).
You can try uninstalling python3 and upgrade pip3
brew uninstall --ignore-dependencies python3
pip3 install --upgrade pip
This worked for me ;)

(NOT on Windows!)
This made me tear my hair out for a week, so I hope this will help someone
I tried everything short of re-installing Anaconda and/or Jupyter.
Setup
AWS Linux
Manually installed Anaconda 3-5.3.0
Python3 (3.7) was running inside anaconda (ie, ./anaconda3/bin/python)
there was also /usr/bin/python and /usr/bin/python3 (but these were not being used as most of the work was done in Jupyter's terminal)
Fix
In Jupyter's terminal:
cp /usr/lib64/libssl.so.10 ./anaconda3/lib/libssl.so.1.0.0
cp /usr/lib64/libcrypto.so.10 ./anaconda3/lib/libcrypto.so.1.0.0
What triggered this?
So, this was all working until I tried to do a conda install conda-forge
I'm not sure what happened, but conda must have updated openssl on the box (I'm guessing) so after this, everything broke.
Basically, unknown to me, conda had updated openssl, but somehow deleted the old libraries and replaced it with libssl.so.1.1 and libcrypto.so.1.1.
Python3, I guess, was compiled to look for libssl.so.1.0.0
In the end, the key to diagnosis was this:
python -c "import ssl; print (ssl.OPENSSL_VERSION)"
gave the clue library "libssl.so.1.0.0" not found
The huge assumption I made is that the yum version of ssl is the same as the conda version, so just renaming the shared object might work, and it did.
My other solution was to re-compile python, re-install anaconda, etc, but in the end I'm glad I didn't need to.
Hope this helps you guys out.

In the case of using pyenv to manage python installations on Mac OS Catalina, I had to install openssl with brew first and then after that run pyenv install 3.7.8 which seemed to build the python installation using the openssl from homebrew (it even said as such in the installation output). Then pyenv global 3.7.8 and I was away.

On macos, configure python 3.8.1 with the command below will solve the problem, i think it would also work on Linux.
./configure --enable-optimizations --with-openssl=/usr/local/opt/openssl#1.1/
change the dir parameter based on your system.

I've made some PATH changes to mimic part of the Anaconda Powershell Prompt $env:PATH
C:\Users\merheb\Miniconda3;C:\Users\merheb\Miniconda3\Library\mingw-w64\bin;C:\Users\merheb\Miniconda3\Library\usr\bin;C:\Users\merheb\Miniconda3\Library\bin;C:\Users\merheb\Miniconda3\Scripts;C:\Users\merheb\Miniconda3\bin;C:\Users\merheb\Miniconda3\condabin;
And It worked for me.

Building from source was what worked for me on Ubuntu 22.10:
Install OpenSSL manually, tested here with OpenSSL 1.1.1s, extracted then ran:
./config --prefix='/opt/openssl' --openssldir='/opt/ssl'
make
make install
Then with your older Python 3 version (here Python-3.8.16) run:
export LD_RUN_PATH='/opt/openssl/lib'
export CC='gcc-12' # sudo apt install gcc-12
./configure --enable-optimizations \
--with-openssl='/opt/openssl' \
--prefix='/opt/python/3.8' -C
make
make install
Test with:
/opt/python/3.8/bin/python3 -c 'import ssl; print(ssl.OPENSSL_VERSION)'
OpenSSL 1.1.1s 1 Nov 2022

The python documentation is actually very clear, and following the instructions did the job whereas other answers I found here were not fixing this issue.
first, install python 3.x.x from source using, for example with version 3.6.2 https://www.python.org/ftp/python/3.6.2/Python-3.6.2.tar.xz
make sure you have openssl installed by running brew install openssl
unzip it and move to the python directory: tar xvzf Python-3.6.2.tar.xz && cd Python-3.6.2
then if the python version is < 3.7, run
CPPFLAGS="-I$(brew --prefix openssl)/include" \
LDFLAGS="-L$(brew --prefix openssl)/lib" \
./configure --with-pydebug
5. finallly, run make -s -j2 (-s is the silent flag, -j2 tells your machine to use 2 jobs)

I had the same issue trying to install python3.7 on an ubuntu14.04 machine.
The issue was that I had some custom folders in my PKG_CONFIG_PATH and in my LD_LIBRARY_PATH, which prevented the python build process to find the system openssl libraries.
so try to clear them and see what happens:
export PKG_CONFIG_PATH=""
export LD_LIBRARY_PATH=""

Ok the latest answer to this, as of now don't use Python 3.8, use only 3.7 or less , because of most of the libraries fail to install with the above error

pg_config executable not found on Windows 7 with PostgreSQL installed [duplicate]

I'm using virtualenv and I need to install "psycopg2".
I have done the following:
pip install http://pypi.python.org/packages/source/p/psycopg2/psycopg2-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
And I have the following messages:
Downloading/unpacking http://pypi.python.org/packages/source/p/psycopg2/psycopg2
-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
Downloading psycopg2-2.4.tar.gz (607Kb): 607Kb downloaded
Running setup.py egg_info for package from http://pypi.python.org/packages/sou
rce/p/psycopg2/psycopg2-2.4.tar.gz#md5=24f4368e2cfdc1a2b03282ddda814160
Error: pg_config executable not found.
Please add the directory containing pg_config to the PATH
or specify the full executable path with the option:
python setup.py build_ext --pg-config /path/to/pg_config build ...
or with the pg_config option in 'setup.cfg'.
Complete output from command python setup.py egg_info:
running egg_info
creating pip-egg-info\psycopg2.egg-info
writing pip-egg-info\psycopg2.egg-info\PKG-INFO
writing top-level names to pip-egg-info\psycopg2.egg-info\top_level.txt
writing dependency_links to pip-egg-info\psycopg2.egg-info\dependency_links.txt
writing manifest file 'pip-egg-info\psycopg2.egg-info\SOURCES.txt'
warning: manifest_maker: standard file '-c' not found
Error: pg_config executable not found.
Please add the directory containing pg_config to the PATH
or specify the full executable path with the option:
python setup.py build_ext --pg-config /path/to/pg_config build ...
or with the pg_config option in 'setup.cfg'.
----------------------------------------
Command python setup.py egg_info failed with error code 1
Storing complete log in C:\Documents and Settings\anlopes\Application Data\pip\p
ip.log
My question, I only need to do this to get the psycopg2 working?
python setup.py build_ext --pg-config /path/to/pg_config build ...

Note: Since a while back, there are binary wheels for Windows in PyPI, so this should no longer be an issue for Windows users. Below are solutions for Linux, Mac users, since lots of them find this post through web searches.
Option 1
Install the psycopg2-binary PyPI package instead, it has Python wheels for Linux and Mac OS.
pip install psycopg2-binary
Option 2
Install the prerequsisites for building the psycopg2 package from source:
Debian/Ubuntu
Python 3
sudo apt install libpq-dev python3-dev
You might need to install python3.8-dev or similar for e.g. Python 3.8.
Python 2
sudo apt install libpq-dev python-dev
If that's not enough, try
sudo apt install build-essential
or
sudo apt install postgresql-server-dev-all
as well before installing psycopg2 again.
CentOS 6
See Banjer's answer
macOS
See nichochar's answer

On CentOS, you need the postgres dev packages:
sudo yum install python-devel postgresql-devel
That was the solution on CentOS 6 at least.

If you're on a mac you can use homebrew
brew install postgresql
And all other options are here: http://www.postgresql.org/download/macosx/

On Mac Mavericks with Postgres.app version 9.3.2.0 RC2 I needed to use the following code after installing Postgres:
sudo PATH=$PATH:/Applications/Postgres.app/Contents/Versions/9.3/bin pip install psycopg2

I recently configured psycopg2 on a windows machine. The easiest install is using a windows executable binary. You can find it at http://stickpeople.com/projects/python/win-psycopg/.
To install the native binary in a virtual envrionment, use easy_install:
C:\virtualenv\Scripts\> activate.bat
(virtualenv) C:\virtualenv\Scripts\> easy_install psycopg2-2.5.win32-py2.7-pg9.2.4-release.exe

For Python 3 you should use sudo apt-get install libpq-dev python3-dev under Debian.

This is what worked for me (On RHEL, CentOS:
sudo yum install postgresql postgresql-devel python-devel
And now include the path to your postgresql binary dir with you pip install:
sudo PATH=$PATH:/usr/pgsql-9.3/bin/ pip install psycopg2
Make sure to include the correct path. Thats all :)
UPDATE: For python 3, please install python3-devel instead of python-devel

The answers so far are too much like magic recipes. The error that you received tells you that pip cannot find a needed part of the PostgreSQL Query library. Possibly this is because you have it installed in a non-standard place for your OS which is why the message suggests using the --pg-config option.
But a more common reason is that you don't have libpq installed at all. This commonly happens on machines where you do NOT have PostgreSQL server installed because you only want to run client apps, not the server itself. Each OS/distro is different, for instance on Debian/Ubuntu you need to install libpq-dev. This allows you to compile and link code against the PostgreSQL Query library.
Most of the answers also suggest installing a Python dev library. Be careful. If you are only using the default Python installed by your distro, that will work, but if you have a newer version, it could cause problems. If you have built Python on this machine then you already have the dev libraries needed for compiling C/C++ libraries to interface with Python. As long as you are using the correct pip version, the one installed in the same bin folder as the python binary, then you are all set. No need to install the old version.

If you using Mac OS, you should install PostgreSQL from source.
After installation is finished, you need to add this path using:
export PATH=/local/pgsql/bin:$PATH
or you can append the path like this:
export PATH=.../:usr/local/pgsql/bin
in your .profile file or .zshrc file.
This maybe vary by operating system.
You can follow the installation process from http://www.thegeekstuff.com/2009/04/linux-postgresql-install-and-configure-from-source/

On Debian/Ubuntu:
First install and build dependencies of psycopg2 package:
# apt-get build-dep python-psycopg2
Then in your virtual environment, compile and install psycopg2 module:
(env)$ pip install psycopg2

Run below commands and you should be fine
$ apt-get update
$ apt install python3-dev libpq-dev
$ pip3 install psycopg2

I've done this before where in windows you install first into your base python installation.
Then, you manually copy the installed psycopg2 to the virtualenv install.
It's not pretty, but it works.

Before you can install psycopg2 you will need to install the python-dev package.
If you're working from Linux (and possibly other systems but i can't speak from experience) you will need to make sure to be quite exact about what version of python your running when installing the dev package.
For example when I used the command:
sudo apt-get install python3-dev
I still ran into the same error when trying to
pip install psycopg2
As I am using python 3.7 I needed to use the command
sudo apt-get install python3.7-dev
Once I did this I ran into no more issues. Obviously if your on python version 3.5 you would change that 7 to a 5.

Besides installing the required packages, I also needed to manually add PostgreSQL bin directory to PATH.
$vi ~/.bash_profile
Add PATH=/usr/pgsql-9.2/bin:$PATH before export PATH.
$source ~/.bash_profile
$pip install psycopg2

For MacOS,
Use the below command to install psycopg2, works like charm!!!
env LDFLAGS="-I/usr/local/opt/openssl/include -L/usr/local/opt/openssl/lib" pip install psycopg2

On windows XP you get this error if postgres is not installed ...

I installed Postgresql92 using the RedHat / CentOS repository on PG's downloads site http://www.postgresql.org/download/linux/redhat/
To get pg_config, I had to add /usr/pgsql-9.2/bin to PATH.

On Fedora 24: For Python 3.x
sudo dnf install postgresql-devel python3-devel
sudo dnf install redhat-rpm-config
Activate your Virtual Environment:
pip install psycopg2

Psycopg2 Depends on Postgres Libraries.
On Ubuntu You can use:
apt-get install libpq-dev
Then:
pip install psycopg2

I've been battling with this for days, and have finally figured out how to get the "pip install psycopg2" command to run in a virtualenv in Windows (running Cygwin).
I was hitting the "pg_config executable not found." error, but I had already downloaded and installed postgres in Windows. It installed in Cygwin as well; running "which pg_config" in Cygwin gave "/usr/bin/pg_config", and running "pg_config" gave sane output -- however the version installed with Cygwin is:
VERSION = PostgreSQL 8.2.11
This won't work with the current version of psycopg2, which appears to require at least 9.1. When I added "c:\Program Files\PostgreSQL\9.2\bin" to my Windows path, the Cygwin pip installer was able to find the correct version of PostgreSQL, and I was able to successfully install the module using pip. (This is probably preferable to using the Cygwin version of PostgreSQL anyway, as the native version will run much quicker).

On OpenSUSE 13.2, this fixed it:
sudo zypper in postgresql-devel

For lowly Windows users were stuck having to install psycopg2 from the link below, just install it to whatever Python installation you have setup. It will place the folder named "psycopg2" in the site-packages folder of your python installation.
After that, just copy that folder to the site-packages directory of your virtualenv and you will have no problems.
here is the link you can find the executable to install psycopg2
http://www.lfd.uci.edu/~gohlke/pythonlibs/

On Ubuntu I just needed the postgres dev package:
sudo apt-get install postgresql-server-dev-all
*Tested in a virtualenv

I could install it in a windows machine and using Anaconda/Spyder with python 2.7 through the following commands:
!pip install psycopg2
Then to establish the connection to the database:
import psycopg2
conn = psycopg2.connect(dbname='dbname',host='host_name',port='port_number', user='user_name', password='password')

In Arch base distributions:
sudo pacman -S python-psycopg2
pip2 install psycopg2 # Use pip or pip3 to python3

On OSX 10.11.6 (El Capitan)
brew install postgresql
PATH=$PATH:/Library/PostgreSQL/9.4/bin pip install psycopg2

On OSX with macports:
sudo port install postgresql96
export PATH=/opt/local/lib/postgresql96/bin:$PATH

if pip is not working than you can download .whl file from here https://pypi.python.org/pypi/psycopg2
extract it..
than python setup.py install

I was having this problem, the main reason was with 2 equal versions installed. One by postgres.app and one by HomeBrew.
If you choose to keep only the APP:
brew unlink postgresql
pip3 install psycopg2

Installation on MacOS
Following are the steps, which worked for me and my team members while installing psycopg2 on Mac OS Big Sur and which we have extensively tested for Big Sur. Before starting make sure you have the Xcode command-line tool installed. If not, then install it from the Apple Developer site. The below steps assume you have homebrew installed. If you have not installed homebrew then install it. Last but not the least, it also assumes you already have PostgreSQL installed in your system, if not then install it. Different people have different preferences but the default installation method on the official PostgreSQL site via Enterprise DB installer is the best method for the majority of people.
Put up the linkage to pg_config file in your .zshrc file by: export PATH="$PATH:/Library/PostgreSQL/12/bin:$PATH". This way you are having linkage with the pg_config file in the /Library/PostgreSQL/12/bin folder. So if your PostgreSQL installation is via other means, like Postgres.app or Postgres installation via homebrew, then you need to have in your .zshrc file the link to pg_config file from the bin folder of that PostgreSQL installation as psycopg2 relies on that.
Install OpenSSL via Homebrew using the command brew install openssl. The reason for this is that libpq, the library which is the basis of psycopg2, uses openssl - psycopg2 doesn't use it directly. After installing put the following commands in your .zshrc file:
export PATH="/usr/local/opt/openssl#1.1/bin:$PATH"
export LDFLAGS="-L/usr/local/opt/openssl#1.1/lib"
export CPPFLAGS="-I/usr/local/opt/openssl#1.1/include"
By doing this you are creating necessary linkages in your directory. These commands are suggested by brew while you install openssl and have been directly picked up from there.
Now comes the most important step, which is to install libpq using the command brew install libpq. This installs libpq library. As per the documentation
libpq is the C application programmer's interface to PostgreSQL. libpq is a set of library functions that allow client programs to pass queries to the PostgreSQL backend server and to receive the results of these queries.
Link libpq using brew link libpq, if this doesn't work then use the command: brew link libpq --force.
Also put in your .zshrc file the following export PATH="/usr/local/opt/libpq/bin:$PATH". This creates all the necessary linkages for libpq library .
Now restart the terminal or use the following command source ~/.zshrc.
This works even when you are working in conda environment.
N.B. pip install psycopg2-binaryshould be avoided because as per the developers of the psycopg2 library
The use of the -binary packages in production is discouraged because in the past they proved unreliable in multithread environments. This might have been fixed in more recent versions but I have never managed to reproduce the failure.

SSL backend error when using OpenSSL

I was trying to install pycurl in a virtualenv using pip and I got this error
ImportError: pycurl: libcurl link-time ssl backend (openssl) is different from compile-time ssl backend (none/other)
I read some documentation saying that "To fix this, you need to tell setup.py what SSL backend is used" (source) although I am not sure how to do this since I installed pycurl using pip.
How can I specify the SSL backend when installing pycurl with pip?
Thanks

for most people
After reading their INSTALLATION file, I was able to solve my problem by setting an environment variable and did a reinstall
# remove existing `pycurl` installation
pip uninstall pycurl
# export variable with your link-time ssl backend (which is openssl above)
export PYCURL_SSL_LIBRARY=openssl
# then, re-install `pycurl` with **no cache**
pip install pycurl --no-cache-dir
There could be other solution out there but this works perfectly for me on a virtualenv and pip installation.
Some people have a different error message complaining about nss instead of openssl
ImportError: pycurl: libcurl link-time ssl backend (nss)
(the key part is nss) so you have to do something different for this error message:
pip uninstall pycurl
pip install --no-cache-dir --compile --compile-options="--with-nss" pycurl

helloworld2013's answer is correct, but the key is matching the SSL library that pycurl is expecting. The error will be something like:
pycurl: libcurl link-time ssl backend (<library>) is different from compile-time ssl backend (<library> or "none/other")
To fix it, you have to use the library pycurl is expecting. In my case, my error was "pycurl: libcurl link-time ssl backend (nss) is different from compile-time ssl backend (openssl)", so my fix was:
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=nss
pip install pycurl

With macOS 10.13, a brew-installed openSSL, and virtualenv, I was successful with:
# cd to your virtualenv, then…
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=openssl
export LDFLAGS=-L/usr/local/opt/openssl/lib
export CPPFLAGS=-I/usr/local/opt/openssl/include
pip install pycurl --compile --no-cache-dir

With pip 7.1 you can put the following in your requirements file:
pycurl==7.19.5.1 --global-option="--with-nss"
Simply replace nss with the relevant ssl backend library.

The method to fix the pycurl after Mac OS High Sierra update:
Reinstall the curl libraries to use OpenSSL instead of SecureTransport
brew install curl --with-openssl
Install pycurl with correct build-time environment and paths
export PYCURL_SSL_LIBRARY=openssl
pip uninstall pycurl
pip install --no-cache-dir --global-option=build_ext --global-option="-L/usr/local/opt/openssl/lib" --global-option="-I/usr/local/opt/openssl/include" --user pycurl

This worked for me:
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=nss
easy_install pycurl
None of this worked for me (note the difference is simply easy_install vs pip):
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=[nss|openssl|ssl|gnutls]
pip install pycurl
#xor
curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.19.3.1.tar.gz
#...
python setup.py --with-[nss|openssl|ssl|gnutls] install

I had this problem for days. Finally with the help of other answers here (mainly Alexander Tyapkov's) I got it working for AWS Elastic Beanstalk.
Manual install (connecting with SSH):
sudo pip uninstall pycurl
curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
sudo pip install pycurl-7.43.0.tar.gz --global-option="--with-nss"
IMPORTANT: Please note that you have to make sure you are using the currect version of Python and PIP, otherwise you might be compiling it for Python 2.x and using v3.x.
Auto-install in Elastic Beanstalk:
files:
"/usr/local/share/pycurl-7.43.0.tar.gz" :
mode: "000644"
owner: root
group: root
source: https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
commands:
01_download_pip3:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
command: 'curl -O https://bootstrap.pypa.io/get-pip.py'
02_install_pip3:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
command: 'python3 get-pip.py'
03_pycurl_uninstall:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
command: '/usr/bin/yes | sudo pip uninstall pycurl'
04_pycurl_download:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
command: 'curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz'
05_pycurl_reinstall:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
command: 'sudo pip install pycurl-7.43.0.tar.gz --global-option="--with-nss"'
container_commands:
09_pycurl_reinstall:
# run this before PIP installs requirements as it needs to be compiled with OpenSSL
# the upgrade option is because it will run after PIP installs the requirements.txt file.
# and it needs to be done with the virtual-env activated
command: 'source /opt/python/run/venv/bin/activate && pip3 install /usr/local/share/pycurl-7.43.0.tar.gz --global-option="--with-nss" --upgrade'
I had this problem because I was trying to configure Celery 4 with Django 1.10 in Elastic Beanstalk. If that's your case, I wrote a full blog post about it.

I'm on CentOS 7. I tried all of the above and couldn't get anything to work. It turns out I needed to run these as a root user. So if you're having trouble, try any of the above solutions as a root user. As an example, here is what worked for me:
su -
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=[nss|openssl|ssl|gnutls]
pip install pycurl
Of course, all the usual disclaimers about running as a root user apply.
Note: [nss|openssl|ssl|gnutls] in the code above means to pick one, and don't include the square brackets or pipes. The person who asked the original question would have chosen openssl. In my particular case, I chose nss. Your error message should tell you which choice to make.
2019 Edit: Doing a sudo pip install might cause a problem with the machine's system install of Python. Perhaps try working in a Python virtual environment and install the packages there. If that doesn't work, the sudo trick in my answer is probably one of the last options to consider.

You can download the tar.gz file from here. Then extract it into a folder. You'll find a setup.py file there. Run the command over there that the site mentioned. For example:
python setup.py --with-[ssl|gnutls|nss] install
FYI: I tried to install pycurl at my windows, but I couldn't. But did it on my linux.

I am running this on OS X and some of the above solutions weren't working. Similar to Edward Newell's comment the PYCURL_SSL_LIBRARY variable seemed to have been completely ignored.
Further reading of the PycURL installation doc revealed the following:
pip may reinstall the package it has previously compiled instead of recompiling pycurl with newly specified options
Therefore, I had to force it to compile with:
pip install --compile pycurl
That works on a number of cases. However, I did run into a few systems that continued to ignore the variable so, similar to maharg101's answer, I resorted to the install options which through pip can be set like this:
pip install pycurl --global-option="--with-[ssl|gnutls|nss]"
where you select one of the three options inside the square brackets. Notice that the available option is ssl and not openssl. If you specify --with-openssl you'll get an error. Also note that if you were messing around with the PYCURL_SSL_LIBRARY variable and switching it to funky values to see what would happen this last command will definitely catch it and throw an error if the value is set but not valid.

For anyone having problem inside PyCharm CE on macOS
Mojave this is how i got it working in venv:
specify version: 7.43.0.1
Options: --install-option=--with-openssl --install-option=--openssl-dir=/usr/local/opt/openssl

Reinstallation of curl
I tried every suggestion from this discussion but no one worked for me. As solution I have reinstalled curl and curlib. After that I was able to install pycurl with ssl support inside environment.
At start:
'PycURL/7.43.0 libcurl/7.47.0 GnuTLS/3.4.10 zlib/1.2.8 libidn/1.32
librtmp/2.3'
Part 1.Re/Installation with pip
Firstly I have removed pycurl from virtualenv using pip as was suggested previous answers:
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=openssl
pip install pycurl --global-option="--with-openssl"
The idea here is that package was cached and we just reintstall it with openssl option.
I also tried to recompile pycurl with pip using:
pip install pycurl --compile pycurl --no-cache
..but had the same error after running:
python
import pycurl
pycurl.version
ImportError: pycurl: libcurl link-time ssl backend (gnutls) is
different from compile-time ssl backend (openssl)
Part 2. Installation from tar
After previous method didn't work I have decidede to install pycurl from tar with:
curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
sudo tar -xzvf pycurl-7.43.0.tar.gz
cd pycurl-7.43.0/
sudo python setup.py --with-ssl install
It has installed pycurl globally but not within virtualenv. I also didn't check if it was installed with SSL support or not but think that still without ssl.
Part 3. Reinstallation of curl and curllib
Finally I understood that pycurl doesn't installs normally into environment because global curl and libcurl are compiled with gnutls.
Before starting check it with:
curl-config --configure
One of the output lines will be
'--without-ssl' '--with-gnutls'
To recompile it:
Firstly remove curl:
sudo apt-get purge curl
Install any build dependencies needed for curl
sudo apt-get build-dep curl
Get latest (as of Dec 20, 2016) libcurl
mkdir ~/curl
wget http://curl.haxx.se/download/curl-7.51.0.tar.bz2
tar -xvjf curl-7.51.0.tar.bz2
cd curl-7.51.0
The usual steps for building an app from source
./configure
./make
sudo make install
If openssl installed correctly then configure will find it automatically. The output will be:
curl version: 7.51.0
Host setup: x86_64-pc-linux-gnu
Install prefix: /usr/local
Compiler: gcc
SSL support: enabled (OpenSSL) ...
Resolve any issues of C-level lib location caches ("shared library cache")
sudo ldconfig
Now try to reinstall pycurl within environment:
curl -O https://pypi.python.org/packages/source/p/pycurl/pycurl-7.43.0.tar.gz
pip install pycurl-7.43.0.tar.gz --global-option="--with-openssl"
The result should be:
python
import pycurl
pycurl.version
'PycURL/7.43.0 libcurl/7.51.0 OpenSSL/1.0.2g zlib/1.2.8 librtmp/2.3'

I tried everything here on macOS 10.13 with no success. Then I found https://gist.github.com/webinista/b4b6a4cf8f158431b2c5134630c2cbfe which worked:
brew install curl --with-openssl
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=openssl
export LDFLAGS=-L/usr/local/opt/openssl/lib;export CPPFLAGS=-I/usr/local/opt/openssl/include; pip install pycurl --compile --no-cache-dir
This worked for me both when not using a virtualenv and within a virtualenv.

This worked for me:
pip install --compile --install-option="--with-openssl" pycurl

Not sure if this is because of running in a virtualenv, but on CentOS 7 these solutions weren't working for me; the compiled objects were still being grabbed from the cache dir when I was reinstalling. If you're running into the same problem after trying other solutions here, try the following:
pip uninstall pycurl
export PYCURL_SSL_LIBRARY=[nss|openssl|ssl|gnutls]
pip install pycurl --no-cache-dir

Error:
ImportError: pycurl: libcurl link-time ssl backend (openssl) is different from compile-time ssl backend (none/other)
This worked for me, Mac 10.13, python 3.5, pycurl import worked after installing like this
pip3 uninstall pycurl;
pip3 install --compile --install-option="--with-openssl" pycurl

After being stuck on this for a long time, I found out that apple stopped including OpenSSL headers since OS X 10.11 El Capitan.
how to fix?
1) brew install openssl
2) echo 'export PATH="/usr/local/opt/openssl/bin:$PATH"' >> ~/.bash_profile (or .zshrc for zsh, etc)
3) pip uninstall pycurl
4) pip install --install-option="--with-openssl" --install-option="--openssl-dir=/usr/local/opt/openssl" pycurl

Same problem on amazonlinux - solved
I had this problem while creating a docker image based on amazonlinux, installing python3.7 and adding the pycurl module.
All other python modules were installed correctly except pycurl.
After trying many of the solutions proposed in the threads linked to this problem I finally solved my problem by using following commands for installation of all the pieces.
yum -y install python3 python3-devel gcc libcurl-devel aws-cli openssl-static.x86_64
then installed other modules like psycopg2-binary, requests, certifi using:
pip3 install --user --no-cache-dir -r requirements.txt
and finally installed pycurl module using:
pip3 install --user --global-option="--with-openssl" --no-cache-dir pycurl
and passing here the openssl global option.
The installation of the static library openssl-static.x86_64 solved the problem in my case as using global option used by the second pip3 command.

For python 2.7
sudo apt-get install build-essential libssl-dev libffi-dev python-dev
For python 3.5 also install the next:
sudo apt-get install python3.5-dev
Download the latest pycurl-7.43.0.tar.gz (md5) Source from pypi https://pypi.python.org/pypi/pycurl/7.43.0#downloads
and run the next command:
python setup.py --with-openssl install
Also you can do it into python environment:
(test_env)user#pc:~/Downloads/pycurl-7.43.0$ python setup.py --with-openssl install

pip install -U pip
if [ "$(curl --version | grep NSS 2>/dev/null)" ]; then
pip install --compile --install-option="--with-nss" pycurl
else
pip install --compile --install-option="--with-openssl" pycurl
fi

I encountered this problem and Sanket Jagtap's answer worked for me. I tried the answer with the most votes answer but it did not work.
My openssl old version is 1.0.1t, I think reinstalling openssl may solve this problem.
--- pycurl's openssl backend time....
I rebuilt the latest openssl and tried this answer. Check this out.
pip install --compile --install-option="--with-openssl" pycurl
This worked for me.
i recommend we should reinstall our openssl for try..

Following worked for me with Python3.6
MacOS High-Sierra
sudo pip3 uninstall pycurl
sudo pip3 install --compile --install-option="--with-openssl" pycurl
CentOS 7
sudo pip3 uninstall pycurl
sudo pip3 install --compile --install-option="--with-nss" pycurl

This link sums up the reason why the errors occur and gives a clear instruction to fix the problem.
https://cscheng.info/2018/01/26/installing-pycurl-on-macos-high-sierra.html
For me, the problem occurred when I upgraded to High-Sierra from El
Captain.

FWIW, I ran into a lot of issues getting this working via AWS Elastic Beanstalk and finally was able to get it working with:
packages:
yum:
openssl-devel: []
libcurl-devel: []
container_commands:
# Reinstall PyCurl with correct ssl backend
05_reinstall_pycurl:
command: |
pip install --upgrade pip
pip uninstall -y pycurl
pip install --global-option='--with-openssl' pycurl

Recently while upgrading a Django project I had the similar error. But this time setting the environment variable did not work. So I had to set both environment variable export PYCURL_SSL_LIBRARY=openssl and pass the flag --global-option="with-openssl".
The original answer was posted on this page

export CPPFLAGS=-I/usr/local/opt/openssl/include
export LDFLAGS=-L/usr/local/opt/openssl/lib
pip install pycurl --global-option="--with-openssl"

Error installing python-snappy: snappy-c.h: No such file or directory

I am using amazon ec2 ubuntu 11.04 server
sudo pip install python-snappy
also I tried to downloaded package and entered "sudo python setup.py install"
I got the error:
running build
running build_ext
building 'snappy' extension
gcc -pthread -fno-strict-aliasing -DNDEBUG -g -fwrapv -O2 -Wall -Wstrict-prototypes -fPIC -I/usr/include/python2.7 -c snappymodule.cc -o build/temp.linux-x86_64-2.7/snappymodule.o
cc1plus: warning: command line option ‘-Wstrict-prototypes’ is valid for Ada/C/ObjC but not for C++ [enabled by default]
snappymodule.cc:31:22: fatal error: snappy-c.h: No such file or directory
compilation terminated.
error: command 'gcc' failed with exit status 1
How i could get rid of this error?
source: https://github.com/andrix/python-snappy

You can install Snappy C library with following commands:
DEB-based: sudo apt-get install libsnappy-dev
RPM-based: sudo yum install csnappy-devel
Alpine (Docker) apk add --no-cache snappy-dev g++
MacOS: See Riley's answer below.

According to the repo
How to install it on Mac OS X?
It has been reported a few times (Issue #7 and #23) that it can't be installed correctly the library in Mac.
The procedure should be,
$ brew install snappy # snappy library from Google
$ CPPFLAGS="-I/usr/local/include -L/usr/local/lib" pip install python-snappy

You need Snappy C library
Then you have to install python-snappy wrapper.
It seems you didn't install Snappy-C library
Try it ..as already a fellow commented for your post
UPDATE: See more highly upvoted post below, which includes instructions to install on DEB-based, RPM-based, and Mac OS (Brew).

You download snappy lib at here: https://code.google.com/p/snappy/
Extract it
Install by command lines follows:
$: ./configure
$: make
$: make install
Install python-snappy:
$: pip install python-snappy

I had some trouble getting snappy to install. Finally downloaded the pre-build stuff as offered by https://www.lfd.uci.edu/~gohlke/pythonlibs/ and all went well.
(Unofficial Windows Binaries for Python Extension Packages)

for Oracle Linux with Python 3.X:
you need to enable optional_latest repository as a first step,
use for enabling the following repo
$ yum-config-manager --enable ol7_optional_latest
"ol7_optional_latest" repo will be enabled for yum lookup.
then install packages using,
$ yum -y install gcc gcc-c++ snappy snappy-devel
then with pip install the python-snappy package,
$ pip3 install python-snappy

had lots of issues installing on El Capitan, with an error saying that the snappy-c.h file was not found.
Had to install snappy from tar.gz file
https://github.com/google/snappy/releases/download/1.1.3/snappy-1.1.3.tar.gz
untar and run
./configure
make
make install
it will put the header file in
/usr/local/include
then needed to set FLAGS for the cc compiler to find the header file:
export DYLD_LIBRARY_PATH=/usr/local/include
export CPPFLAGS="-I/usr/local/include/snappy-c.h"
export CFLAGS="-I/usr/local/include/snappy-c.h"
export CXXFLAGS="-I/usr/local/include/snappy-c.h"
export LDFLAGS="-L/usr/local/lib"
and then I installed python-snappy from the egg file
https://pypi.python.org/packages/b1/fe/1d632cdac5dbb5ce84db778af7f733eb469130d8cf4c02f6cd9057a96768/snappy-2.4.1-py2.7-macosx-10.5-intel.egg#md5=b76558c71f1d97feeb8402c345e466bf
you can try with pip install python-snappy
but it originally failed to find the header file, so i went for the egg file
to install the egg:
easy_install <eggfile>
python setup.py build
python setup.py install

You need to check the output for
rpm -q snappy-devel
If it is not present, then install it using this command:
yum install snappy-devel

If you are on Mac OS X Catalina, you can install with
brew install snappy
CPPFLAGS="-I/usr/local/include -L/usr/local/lib -stdlib=libc++ " pip install python-snappy
as suggested by https://github.com/andrix/python-snappy FAQ

Fix for macOS M1. You have to define absolute path to lib and include for snappy.
brew install snappy
pip install \
--upgrade --ignore-installed \
python-snappy==0.5.4 \
--global-option=build_ext \
--global-option="-I/opt/homebrew/Cellar/snappy/1.1.9/include" \
--global-option="-L/opt/homebrew/Cellar/snappy/1.1.9/lib"

This fixed my issue:
yum install gcc-c++

I was having troubles with this for a while. FYI I'm trying to install Crossbar (https://crossbar.io/docs/Installation-on-Linux/)
I did a bunch of googling and messed around quite a bit. I'm using Python 3.7.4 and what I think solved my problem is this :
sudo yum install python-devel
if that doesn't work try
sudo yum install python3-devel
source:
https://github.com/giampaolo/psutil/issues/1143#issuecomment-475354786
https://github.com/giampaolo/psutil/issues/1143

To solve this issue in Mac OS X with MacPorts installed, you can do:
$ sudo port install snappy
$ CPPFLAGS="-I/opt/local/include -L/opt/local/lib" pip install python-snappy

For Windows
Download from here
Extract the Zip.
Copy the .h files from include folder. Paste in to the python installation folder
C:\Users\user\AppData\Local\Programs\Python\Python310\include\
Copy snappy64.lib from native folder. Paste in to python installation folder
C:\Users\user\AppData\Local\Programs\Python\Python310\libs\
Rename snappy64.lib to snappy.lib
you are good to go. Re-try command pip install -r .\requirements.txt

Develop Reference

Python is a programming language that lets you work quickly and integrate systems more effectively.