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I've installed a library using the command
pip install git+git://github.com/mozilla/elasticutils.git
which installs it directly from a Github repository. This works fine and I want to have that dependency in my requirements.txt. I've looked at other tickets like this but that didn't solve my problem. If I put something like
-f git+git://github.com/mozilla/elasticutils.git
elasticutils==0.7.dev
in the requirements.txt file, a pip install -r requirements.txt results in the following output:
Downloading/unpacking elasticutils==0.7.dev (from -r requirements.txt (line 20))
Could not find a version that satisfies the requirement elasticutils==0.7.dev (from -r requirements.txt (line 20)) (from versions: )
No distributions matching the version for elasticutils==0.7.dev (from -r requirements.txt (line 20))
The documentation of the requirements file does not mention links using the git+git protocol specifier, so maybe this is just not supported.
Does anybody have a solution for my problem?
Normally your requirements.txt file would look something like this:
package-one==1.9.4
package-two==3.7.1
package-three==1.0.1
...
To specify a Github repo, you do not need the package-name== convention.
The examples below update package-two using a GitHub repo. The text between # and # denotes the specifics of the package.
Specify commit hash (41b95ec in the context of updated requirements.txt):
package-one==1.9.4
git+https://github.com/path/to/package-two#41b95ec#egg=package-two
package-three==1.0.1
Specify branch name (master):
git+https://github.com/path/to/package-two#master#egg=package-two
Specify tag (0.1):
git+https://github.com/path/to/package-two#0.1#egg=package-two
Specify release (3.7.1):
git+https://github.com/path/to/package-two#releases/tag/v3.7.1#egg=package-two
Note that #egg=package-two is not a comment here, it is to explicitly state the package name
This blog post has some more discussion on the topic.
“Editable” packages syntax can be used in requirements.txt to import packages from a variety of VCS (git, hg, bzr, svn):
-e git://github.com/mozilla/elasticutils.git#egg=elasticutils
Also, it is possible to point to particular commit:
-e git://github.com/mozilla/elasticutils.git#000b14389171a9f0d7d713466b32bc649b0bed8e#egg=elasticutils
requirements.txt allows the following ways of specifying a dependency on a package in a git repository as of pip 7.0:1
[-e] git+git://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+https://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+ssh://git.myproject.org/SomeProject#egg=SomeProject
-e git+git#git.myproject.org:SomeProject#egg=SomeProject (deprecated as of Jan 2020)
For Github that means you can do (notice the omitted -e):
git+git://github.com/mozilla/elasticutils.git#egg=elasticutils
Why the extra answer?
I got somewhat confused by the -e flag in the other answers so here's my clarification:
The -e or --editable flag means that the package is installed in <venv path>/src/SomeProject and thus not in the deeply buried <venv path>/lib/pythonX.X/site-packages/SomeProject it would otherwise be placed in.2
Documentation
1 https://pip.readthedocs.org/en/stable/reference/pip_install/#git
2 https://pip.readthedocs.org/en/stable/reference/pip_install/#vcs-support
First, install with git+git or git+https, in any way you know. Example of installing kronok's branch of the brabeion project:
pip install -e git+https://github.com/kronok/brabeion.git#12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion
Second, use pip freeze > requirements.txt to get the right thing in your requirements.txt. In this case, you will get
-e git+https://github.com/kronok/brabeion.git#12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion-master
Third, test the result:
pip uninstall brabeion
pip install -r requirements.txt
Since pip v1.5, (released Jan 1 2014: CHANGELOG, PR) you may also specify a subdirectory of a git repo to contain your module. The syntax looks like this:
pip install -e git+https://git.repo/some_repo.git#egg=my_subdir_pkg&subdirectory=my_subdir_pkg # install a python package from a repo subdirectory
Note: As a pip module author, ideally you'd probably want to publish your module in it's own top-level repo if you can. Yet this feature is helpful for some pre-existing repos that contain python modules in subdirectories. You might be forced to install them this way if they are not published to pypi too.
None of these answers worked for me. The only thing that worked was:
git+https://github.com/path_to_my_project.git
No "e", no double "git" and no previous installs necessary.
Github has zip endpoints that in my opinion are preferable to using the git protocol. The advantages are:
You don't have to specify #egg=<project name>
Git doesn't need to be installed in your environment, which is nice for containerized environments
It works much better with pip hashing and caching
The URL structure is easier to remember and more discoverable
You usually want requirements.txt entries to look like this, e.g. without the -e prefix:
https://github.com/org/package/archive/1a58aa586efd4bca37f2cfb9d9348958986aab6c.tar.gz
To install from main branch:
https://github.com/org/package/archive/main.tar.gz
There is also an equivalent .zip endpoint, but it was reported in a comment that always using the .tar.gz endpoint avoids problems with unicode package names.
It seems like this is also a valid format:
gym-tictactoe # git+https://github.com/haje01/gym-tictactoe.git#84e22fc28fe192ba0040bdd56a697f63d3d4a3d5
If you do a pip install "git+https://github.com/haje01/gym-tictactoe.git", then look at what got installed by running pip freeze, you will see the package described in this format and can copy and paste into requirements.txt.
I'm finding that it's kind of tricky to get pip3 (v9.0.1, as installed by Ubuntu 18.04's package manager) to actually install the thing I tell it to install. I'm posting this answer to save anyone's time who runs into this problem.
Putting this into a requirements.txt file failed:
git+git://github.com/myname/myrepo.git#my-branch#egg=eggname
By "failed" I mean that while it downloaded the code from Git, it ended up installing the original version of the code, as found on PyPi, instead of the code in the repo on that branch.
However, installing the commmit instead of the branch name works:
git+git://github.com/myname/myrepo.git#d27d07c9e862feb939e56d0df19d5733ea7b4f4d#egg=eggname
For private repositories, I found that these two work fine for me:
pip install https://${GITHUB_TOKEN}#github.com/owner/repo/archive/main.tar.gz
Where main.tar.gz refers to the main branch of your repo and can be replaced with other branch names. For more information and using the more recent Github API see here:
pip install https://${GITHUB_TOKEN}#api.github.com/repos/owner/repo/tarball/master
If you have git installed and available, then
pip install git+https://${GITHUB_TOKEN}#github.com/owner/repo.git#main
achieves the same, and it also allows for some more flexibility by appending #branch or #tag or #commit-hash. That approach, however, actually clones the repo into a local temp folder which can take a noticeable amount of time.
You can use the URLs in your requirements.txt, too.
I've installed a library using the command
pip install git+git://github.com/mozilla/elasticutils.git
which installs it directly from a Github repository. This works fine and I want to have that dependency in my requirements.txt. I've looked at other tickets like this but that didn't solve my problem. If I put something like
-f git+git://github.com/mozilla/elasticutils.git
elasticutils==0.7.dev
in the requirements.txt file, a pip install -r requirements.txt results in the following output:
Downloading/unpacking elasticutils==0.7.dev (from -r requirements.txt (line 20))
Could not find a version that satisfies the requirement elasticutils==0.7.dev (from -r requirements.txt (line 20)) (from versions: )
No distributions matching the version for elasticutils==0.7.dev (from -r requirements.txt (line 20))
The documentation of the requirements file does not mention links using the git+git protocol specifier, so maybe this is just not supported.
Does anybody have a solution for my problem?
Normally your requirements.txt file would look something like this:
package-one==1.9.4
package-two==3.7.1
package-three==1.0.1
...
To specify a Github repo, you do not need the package-name== convention.
The examples below update package-two using a GitHub repo. The text between # and # denotes the specifics of the package.
Specify commit hash (41b95ec in the context of updated requirements.txt):
package-one==1.9.4
git+https://github.com/path/to/package-two#41b95ec#egg=package-two
package-three==1.0.1
Specify branch name (master):
git+https://github.com/path/to/package-two#master#egg=package-two
Specify tag (0.1):
git+https://github.com/path/to/package-two#0.1#egg=package-two
Specify release (3.7.1):
git+https://github.com/path/to/package-two#releases/tag/v3.7.1#egg=package-two
Note that #egg=package-two is not a comment here, it is to explicitly state the package name
This blog post has some more discussion on the topic.
“Editable” packages syntax can be used in requirements.txt to import packages from a variety of VCS (git, hg, bzr, svn):
-e git://github.com/mozilla/elasticutils.git#egg=elasticutils
Also, it is possible to point to particular commit:
-e git://github.com/mozilla/elasticutils.git#000b14389171a9f0d7d713466b32bc649b0bed8e#egg=elasticutils
requirements.txt allows the following ways of specifying a dependency on a package in a git repository as of pip 7.0:1
[-e] git+git://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+https://git.myproject.org/SomeProject#egg=SomeProject
[-e] git+ssh://git.myproject.org/SomeProject#egg=SomeProject
-e git+git#git.myproject.org:SomeProject#egg=SomeProject (deprecated as of Jan 2020)
For Github that means you can do (notice the omitted -e):
git+git://github.com/mozilla/elasticutils.git#egg=elasticutils
Why the extra answer?
I got somewhat confused by the -e flag in the other answers so here's my clarification:
The -e or --editable flag means that the package is installed in <venv path>/src/SomeProject and thus not in the deeply buried <venv path>/lib/pythonX.X/site-packages/SomeProject it would otherwise be placed in.2
Documentation
1 https://pip.readthedocs.org/en/stable/reference/pip_install/#git
2 https://pip.readthedocs.org/en/stable/reference/pip_install/#vcs-support
First, install with git+git or git+https, in any way you know. Example of installing kronok's branch of the brabeion project:
pip install -e git+https://github.com/kronok/brabeion.git#12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion
Second, use pip freeze > requirements.txt to get the right thing in your requirements.txt. In this case, you will get
-e git+https://github.com/kronok/brabeion.git#12efe6aa06b85ae5ff725d3033e38f624e0a616f#egg=brabeion-master
Third, test the result:
pip uninstall brabeion
pip install -r requirements.txt
Since pip v1.5, (released Jan 1 2014: CHANGELOG, PR) you may also specify a subdirectory of a git repo to contain your module. The syntax looks like this:
pip install -e git+https://git.repo/some_repo.git#egg=my_subdir_pkg&subdirectory=my_subdir_pkg # install a python package from a repo subdirectory
Note: As a pip module author, ideally you'd probably want to publish your module in it's own top-level repo if you can. Yet this feature is helpful for some pre-existing repos that contain python modules in subdirectories. You might be forced to install them this way if they are not published to pypi too.
None of these answers worked for me. The only thing that worked was:
git+https://github.com/path_to_my_project.git
No "e", no double "git" and no previous installs necessary.
Github has zip endpoints that in my opinion are preferable to using the git protocol. The advantages are:
You don't have to specify #egg=<project name>
Git doesn't need to be installed in your environment, which is nice for containerized environments
It works much better with pip hashing and caching
The URL structure is easier to remember and more discoverable
You usually want requirements.txt entries to look like this, e.g. without the -e prefix:
https://github.com/org/package/archive/1a58aa586efd4bca37f2cfb9d9348958986aab6c.tar.gz
To install from main branch:
https://github.com/org/package/archive/main.tar.gz
There is also an equivalent .zip endpoint, but it was reported in a comment that always using the .tar.gz endpoint avoids problems with unicode package names.
It seems like this is also a valid format:
gym-tictactoe # git+https://github.com/haje01/gym-tictactoe.git#84e22fc28fe192ba0040bdd56a697f63d3d4a3d5
If you do a pip install "git+https://github.com/haje01/gym-tictactoe.git", then look at what got installed by running pip freeze, you will see the package described in this format and can copy and paste into requirements.txt.
I'm finding that it's kind of tricky to get pip3 (v9.0.1, as installed by Ubuntu 18.04's package manager) to actually install the thing I tell it to install. I'm posting this answer to save anyone's time who runs into this problem.
Putting this into a requirements.txt file failed:
git+git://github.com/myname/myrepo.git#my-branch#egg=eggname
By "failed" I mean that while it downloaded the code from Git, it ended up installing the original version of the code, as found on PyPi, instead of the code in the repo on that branch.
However, installing the commmit instead of the branch name works:
git+git://github.com/myname/myrepo.git#d27d07c9e862feb939e56d0df19d5733ea7b4f4d#egg=eggname
For private repositories, I found that these two work fine for me:
pip install https://${GITHUB_TOKEN}#github.com/owner/repo/archive/main.tar.gz
Where main.tar.gz refers to the main branch of your repo and can be replaced with other branch names. For more information and using the more recent Github API see here:
pip install https://${GITHUB_TOKEN}#api.github.com/repos/owner/repo/tarball/master
If you have git installed and available, then
pip install git+https://${GITHUB_TOKEN}#github.com/owner/repo.git#main
achieves the same, and it also allows for some more flexibility by appending #branch or #tag or #commit-hash. That approach, however, actually clones the repo into a local temp folder which can take a noticeable amount of time.
You can use the URLs in your requirements.txt, too.
I'm using pip and a requirements.txt file to handle my python packages in my virtualenv. I have a particular package I install from Github so that inside my file I have:
git+ssh://git#github.com/myuser/mypackage.git#egg=mypackage
Since I'm working on the package quite often I need to re-install it but:
pip install -r requirements.txt gives me back
Requirement already satisfied (use --upgrade to upgrade)...
for all the packages in requirements.txt that have new versions.
If I run pip install -r requirements.txt --upgrade it tries to upgrade all my packages (that I do NOT want) but I want to upgrade only mypackage. In requirements.txt I've tried to add a specific commit, like so:
git+ssh://git#github.com/myuser/mypackage.git#733c5b616da27cba14478c24b#egg=mypackage
But when I run pip again it throws:
Requirement already satisfied (use --upgrade to upgrade)..bla bla bla
QUESTION:
Is there a way to upgrade only the specific package mypackage possibily using the requirements.txt file?
Do I need to specify the #egg=mypackage?
The reason you're getting Requirement already satisfied is because if you do not pass --upgrade or -U (the shorthand), the package is not modified if it is already installed.
(This part of the command has had a lot of discussion. Check out the first 4 issues here)
Is there a way to upgrade only the specific package mypackage possibily using the requirements.txt file?
You need to specify just mypackage to pip when telling it to upgrade. If you wanted to update only requests, the pip command is:
pip install --upgrade requests
Similarly, to update from your git repository, you want to do:
pip install --upgrade git+ssh://git#github.com/myuser/mypackage.git#egg=mypackage
Since it's a URL is a long thing, what I suggest you do what #daphtdazz suggests, use multiple requirements files, as follows:
requirements.txt
requests~=2.12.3
simplejson~=3.10.0
-r git_requirements.txt
git_requirements.txt
git+ssh://git#github.com/myuser/mypackage.git#egg=mypackage
Additionally, I suggest you use shell-aliases for your shell to ease the typing load.
alias pip_git_upgrade="pip install --upgrade -r git_requirements.txt"
Do I need to specify the #egg=mypackage?
To quote from pip's official documentation:
Any URL may use the #egg=name syntax to explicitly state the project name.
Basically, using #egg=mypackage is a good idea since you are making the the project name explicit.
If you have dependencies that need to be at a particular version, then you should fix them in your requirements file to stay at that version. So for example (although not realistic):
mock~=2.0.0
pexpect==2.4.1
git+ssh://git#github.com/myuser/mypackage.git#733c5b616da27cba14478c24b#egg=mypackage
mock will be updated to any version that looks like 2.0.* (normally changes in the most minor number are bugfixes, so you generally want this)
pexpect will be fixed at 2.4.1
mypackage will always be updated whenever possible.
If you only want to upgrade a single package though, then just upgrade that one:
pip install -U git+ssh://git#github.com/myuser/mypackage.git
Another alternative if you want to upgrade all of them regularly but some more regularly than others would be to split up the requirements file. See the pip docs. I suspect this needs an up to date version of pip and setuptools (but you're updating those regularly anyway, right??).
For example, you could then have:
update_regularly_reqs.txt
git+ssh://git#github.com/myuser/mypackage.git#733c5b616da27cba14478c24b#egg=mypackage
all_requirements.txt
-r update_regularly_reqs.txt
mock~=2.0.0
pexpect==2.4.1
Edit to add info on #egg=
The #egg=mypackage bit is required if you want to check it out using pip and also edit the code in that package, but then you need to use:
-e git+ssh://...#egg=mypackage
pip will then make a directory in the src directory in your virtualenv's home directory (use cdvirtualenv to find it) with that name, or at least it did on my system, and will check out the code using git clone (or appropriate for Mercurial or SVN if using those) so you can go and edit it in place.
But if you don't specify -e (as you did) then I think it checks it out as a normal package, which makes it harder for you to manage if you want to edit it in place, and then you don't need the #egg= bit.
No doubt there are lots of config options too... a good place to start is that doc I linked.
I've just uploaded a new version of my package to PyPi (1.2.1.0-r4): I can download the egg file and install it with easy_install, and the version checks out correctly. But when I try to install using pip, it installs version 1.1.0.0 instead. Even if I explicitly specify the version to pip with pip install -Iv tome==1.2.1.0-r4, I get this message: Requested tome==1.2.1.0-r4, but installing version 1.1.0.0, but I don't understand why.
I double checked with parse_version and confirmed that the version string on 1.2.1 is greater than that on 1.1.0 as shown:
>>> from pkg_resources import parse_version as pv
>>> pv('1.1.0.0') < pv('1.2.1.0-r4')
True
>>>
So any idea why it's choosing to install 1.1.0 instead?
This is an excellent question. It took me forever to figure out. This is the solution that works for me:
Apparently, if pip can find a local version of the package, pip will prefer the local versions to remote ones. I even disconnected my computer from the internet and tried it again -- when pip still installed the package successfully, and didn't even complain, the source was obviously local.
The really confusing part, in my case, was that pip found the newer versions on pypi, reported them, and then went ahead and re-installed the older version anyway ... arggh. Also, it didn't tell me what it was doing, and why.
So how did I solve this problem?
You can get pip to give verbose output using the -v flag ... but one isn't enough. I RTFM-ed the help, which said you can do -v multiple times, up to 3x, for more verbose output. So I did:
pip install -vvv <my_package>
Then I looked through the output. One line caught my eye:
Source in /tmp/pip-build-root/ has version 0.0.11, which satisfies requirement <my_package>
I deleted that directory, after which pip installed the newest version from pypi.
Try forcing download the package again with:
pip install --no-cache-dir --upgrade <package>
Thanks to Marcus Smith, who does amazing work as a maintener of pip, this was fixed in version 1.4 of pip which was released on 2013-07-23.
Relevant information from the changelog for this version
Fixed a number of issues (#413, #709, #634, #602, and #939) related to
cleaning up and not reusing build directories. (Pull #865, #948)
I found here that there is a known bug in pip that it won't check the version if there's a build directory with unpacked sources. I have checked this on my troubling package and after deleting its sources from build directory pip installed the required version.
If you are using a pip version that comes with some distribution packages (ex. Ubuntu python-pip), you may need to install a newer pip version:
Update pip to latest version:
sudo pip install -U pip
In case of "virtualenv", skip "sudo":
pip install -U pip
Following command may be required, if your shell report something like -bash: /usr/bin/pip: No such file or directory after pip update:
hash -d pip
Now install your package as usual:
pip install -U foo
or
pip install foo==package.version.here
Got the same issue to update pika 0.9.5 to 0.9.8. The only working way was to install from tarball: pip install https://pypi.python.org/packages/source/p/pika/pika-0.9.8.tar.gz.
In my case the python version used (3.4) didn't satisfy Django 2.1 dependencies requirements (python >= 3.5).
For my case I had to delete the .pip folder in my home directory and then I was able to get later versions of multiple libraries. Note that this was on linux.
pip --version
pip 18.1 from /usr/lib/python2.7/site-packages/pip (python 2.7)
virtualenv --version
15.1.0
Just in case that anyone else hassles with upgrading torchtext (or probably any other torch library):
Although https://pypi.org/project/torchtext/ states that you could run pip install torchtext I had to install it similiar to torch by specifying --find-links aka -f:
pip install torchtext===0.8.1 -f https://download.pytorch.org/whl/torch_stable.html
What irritated me was that PyCharm pointed me to the new version, but couldn't find it when attempting to upgrade to it. I guess that PyCharm uses its own mechanism to spot new versions. Then, when invoking pip under the hood, it didn't find the new version without the --find-links option.
In my case I am pip installing a .tar.gz package from Artifactory that I make a lot of updates to. In order to overwrite my cached Python files and always grab/install the latest I was able to run:
pip install --no-cache-dir --force-reinstall <path/to/tar.gz>
You should see this re-download any necessary files and install those, instead of using your local cache.
10 years on and pip still fails to work as expected 😖.
I wasted a couple of hours now banging my head against the wall trying to find out why pip won't install a development version of my package. In my case, there are versions 0.0.4 and 0.0.5.dev1 in a private gitlab.com package registry (hence the --extra-index-url argument below), but I believe that's not relevant to the problem.
Following a lot of the advice on this page, I create a test venv in a far away folder, clear the pip cache, uninstall the package in question, etc. first to rule out the most common problems:
$ pip cache purge && \
pip uninstall --yes my-package && \
pip install --extra-index-url "https://_:${GITLAB_PASSWORD_TOOLS_VAULTTOOLS}#gitlab.com/api/v4/projects/<project-id>/packages/pypi/simple" \
--no-cache-dir \
--pre \
--upgrade my-package
output (using empty lines to separate output for commands):
WARNING: No matching packages
Files removed: 0
Found existing installation: my-package 0.0.4
Uninstalling my-package-0.0.4:
Successfully uninstalled my-package-0.0.4
Looking in indexes: https://pypi.org/simple, https://_:****#gitlab.com/api/v4/projects/<project-id>/packages/pypi/simple
Collecting my-package
Downloading https://gitlab.com/api/v4/projects/<project-id>/packages/pypi/files/f07 ... 397/my_package-0.0.5.dev1-py3-none-any.whl (16 kB)
Downloading https://gitlab.com/api/v4/projects/<project-id>/packages/pypi/files/775 ... 70e/my_package-0.0.4-py3-none-any.whl (16 kB)
...
Successfully installed my-package-0.0.4
So pip does see the dev package version, but chooses the earlier one nonetheless.
In an attempt to figure out what's going on, I published a 0.0.5 version: Error persists, pip sees all three versions, but still installs 0.0.4.
In a further, increasingly desperate attempt, I removed any versions prior to 0.0.5* from the gitlab.com package registry.
Only now, pip would bother to actually display some useful information:
$ (same command as above)
... (similar output as above) ...
ERROR: Cannot install my-package==0.0.5 and my-package==0.0.5.dev1 because these package versions have conflicting dependencies.
The conflict is caused by:
my-package 0.0.5 depends on my-other-package<0.2.5 and >=0.2.4
my-package 0.0.5.dev1 depends on my-other-package<0.2.5 and >=0.2.4
To fix this you could try to:
1. loosen the range of package versions you've specified
2. remove package versions to allow pip attempt to solve the dependency conflict
ERROR: ResolutionImpossible: for help visit https://pip.pypa.io/en/latest/topics/dependency-resolution/#dealing-with-dependency-conflicts
OK, so there is something wrong with my package dependencies. Thanks for letting me know.
Seriously - I tried hard for a couple of hours using all kinds of pip ... -vvv and/or fixed versions such as e.g. my-package==0.0.5.dev1 - but I did not manage to get any useful output out of pip - until I wiped the entire history from my package registry 🤬.
Hope this at least helps someone in the same situation.
I found that if you use microversions, pip doesn't seem to recognize them. For example, we couldn't get version 1.9.9.1 to upgrade.
In my case, someone had published the latest version of a package with python2, so attempting to pip3 install it grabbed an older version that had been built with python3.
Handy things to check when debugging this:
If pip install claims to not be able to find the version, see whether pip search can see it.
Take a look at the "Download Files" section on the pypi repo -- the filenames might suggest what's wrong (in my case i saw -py2- there clear as day).
As suggested by others, try running pip install --no-cache-dir in case pip isn't bothering to ask the internet because it already has your answer locally.
I had hidden unversioned files under the Git tab in PyCharm that were being installed with pip install . even though I didn't see the files anywhere else.
Took a long time to find it for me, posting this in hope that it'll help somebody else.
if you need the path for your package do pip -v list. Example see related post when using pip -e Why is an old version of a package of my python library installing by itself with pip -e?
I feel like there must be a way to do this, but for the life of me I can't figure out how: I want to run pip against a requirements file in a virtualenv so that no matter what packages are in the virtualenv before I run pip, the requirements file is totally fulfilled (including specific versions) after I run it.
The problem now is that if I have an older version of a package installed in the virtualenv than is listed in the requirements file, it complains about the version mismatch and exits (it should just update the package to the given version). The command I'm running is pip install -I -r requirements.txt and according to pip's help, -I is supposed to make pip "Ignore the installed packages (reinstalling instead)" but it definitely isn't doing that.
What am I missing?
(It'd be nice if pip skipped the packages that are already fulfilled too.)
I figured out what the cause of my pip problems was. Long story short, source left over in the virtualenv's build directory was causing an error that made packages upgrades fail. What I actually should have been doing was clearing out that directory (which pip doesn't always do I guess) before running the pip install and it seems to do everything I want after when paired with the --upgrade/-U flag.