Develop Reference

How and where do I deploy a Flask + React web app?

I am building a web app with a Flask backend and a React front end, and I would now like to deploy it, buy a domain, and set it up. What is the easiest way to do this?
Here's my research:
This website shows how to deploy an app on Heroku. I did this, but Heroku seems to be unavailable a lot, at least today.
This blog post seems to suggest I could create a GCE instance and run things there, though (i) it seems like a little more configuration that I'd like (ii) I would need a way to link the nginx server to my domain. I suppose the benefit is that the two apps run on the same machine?
This SO post had OP redo his work and it somehow worked. I'm not sure how to deploy Docker apps online, though.
Is there an easy way to deploy to a reliable service (Google Cloud/AWS/Azure)? My code has the following structure:
build/ # Result of `yarn build`
server/
server.py # Flask server
src/ # React code
Component/
Component.js
Component.sass
index.css
index.js
...
public/
index.html
# Images and other stuff.

I figured out how to do this using Azure. I created an App Service, then installed the Azure Tools VS Code extension. You need to move the Python server to the root directory and rename it to app.py (so the .env is also in the root folder), and then you can right-click your App Service in VS Code (in the Azure Tools tab) and then click Deploy to Web App. Easy!

Heroku not working for Node.js file with python scripts

I made a website in node.js and I have used child process to run python scripts and use their results in my website. But when I host my application on heroku, heroku is unable to run the python scripts.
I have noticed that heroku was able to run python scripts which only had inbuilt python packages like sys, json but it was failing for scripts which were using external packages like requests, beautifulsoup.
Attempt-1
I made a requirements.txt file inside the project folder and pushed my code to heroku again. But it was still not working. I noticed that heroku uses the requirements.txt file only for python based web applications but not for node.js applications.
Attempt-2
I made a python virtual env inside the project folder and imported the required python packages into the venv. I then removed gitignore from the venv and pushed the whole venv folder to heroku. It still didn't work.
Please let me know if anyone came across a way to handle this.

You can use a Procfile to specify a command to install the python dependencies then start the server.
Procfile:
web: pip install -r requirements.txt && npm start
Place Procfile in your project's root directory and deploy to heroku.

Solution:
Have a requirements.txt file in your project folder.
After you create a heroku app using "heroku create", heroku will identify your app as python based and will not download any of the node dependencies.
Now, go to your heroku profile and go to your app's settings. There is an option named "Add Buildpack" in there. Click on that and add node.js as one of the buildpacks.
Go back to your project and push it to heroku. This time heroku will identify your app as both python and node.js based and will download all the required files.

Flask app doesn't builds on MS Azure cloud

I want to deploy my flask web application on Azure cloud. In Deployment options, I have selected GitHub as source destination for my flask code. after doing the configuration test successfully, the init.py file now starts building;
Now when I go to my application link, it shows me this;
Now at this point, I went back to my deployment options, it says Building failed;
the log generated for this building failed can be seen in the first picture. All the tests has passed except the last one "Performance test". Have anyone encountered the same issue before ? what can be the reason for that ?
I am running the application on localhost # port 8000.
from flask import Flask
app = Flask(__name__)
#app.route("/")
def hello():
return "Hello World!"
if __name__ == "__main__":
app.run()
Do I need to run it on another IP ?

You cannot listen on port 8000 in Web Apps. Only port 80 or 443. You'll need to read the port number from the environment, to know what to listen on.

If you created the Azure Webapp using the Flask tool, the default app is called FlaskWebProject1. If your app has a different name, you need to modify web.config in your wwwroot folder to reflect the correct app name.
Then redeploy using the Azure portal or change it in your GIT and push again.

Based on your 500 error, I think some python packages are not installed correctly.
To check your code is working correctly in naive manner, do as follows.
If you are developing on Windows machine, copy all of your site-packages files in development machine to WebApp /site/wwwroot/env/Lib/site-packages folder.
Hit Restart in Azure Portal and F5 in browser.
If it works, your deployment process might have a problem. Mainly it is caused by library installation.
First, check you have requirements.txt at the root folder. This documentation describes some considerations to load Flask on Azure WebApp. Of course, it would be really helpful to read the documentation from the first line carefully.
Second, login WebApp via FTP and check the package is installed correctly. You can see /pip folder has pip.log file, and /site/wwwroot/env/Lib/site-packages folder has its libraries.
For some libraries which you might require more than simple hello world app, you may have to push x86 .whl files along with python codes as they are not installed correctly in x86 environment.
Additionally, in order to show internal error to outside, consider to apply this option during development (not for production).

Getting Django 1.7 to work on Google App Engine

Can anyone help to point us to instructions on how to get Django >1.5 working on Google App Engine? I have seen a number of people claim they have Django 1.6 working. We'd like to get 1.6 or 1.7 running. I have searched here for instructions on how to set this up. No luck so far.
Update:
In our development machine we have Django 1.7 installed (both /user/local and on virtualenv). However, if we modify GAE yaml to use Django 1.7 we get the following error messages:
google.appengine.api.yaml_errors.EventError: django version "1.7" is not supported, use one of: "1.2", "1.3", "1.4", "1.5" or "latest" ("latest" recommended for development only) in "./app.yaml",
The version 1.9.12 GoogleAppEngine sdk install in our /Applications/GoogleAppEngineLauncher.app/Contents/Resources/GoogleAppEngine-default.bundle/Contents/Resources/google_appengine/lib directory shows the following Django versions listed:
django-0.96 django-1.2 django-1.3 django-1.4 django-1.5
My question is related to how to get our development environment setup correctly for Django 1.7 on Google App Engine and how to make sure we successfully deploy our app with Django 1.7 when we deploy to Google App Engine in production. How do we get the Django 1.7 to deploy on GAE when we deploy our app?

You can use any pure Python third party libraries in your Google App Engine application. In order to use a third party library, simply include the files in your application's directory, and they will be uploaded with your application when you deploy it to our system. You can import the files as you would any other Python files with your application.
I have application using Django 1.7 this way and everything is working fine. However, sometimes you may need to sort of hack something due to the App Engine limitations and its specifics. But it depends on your use cases.
I would also suggest to use virtual environment for your project. Install each library that is not supported by App Engine directly via pip and then create a symlink in your application directory pointing to the given library.
This way you can keep all required packages in a file (e.g. requirements.txt) that can be stored in SCM system (e.g. Git) along with your source files and other team members can quite easily replicate your working environment.
Provided that you use virtual environment and install all needed libraries (Django, ...) via pip, here is the directory layout that should work for you.
virtual-env-root
.Python
bin
include
lib
app-engine-project-root
app.yaml
django-project-root
django-app-root
symlink-to-django -> lib/python2.7/site-packages/django
symlink-to-another-lib -> lib/python2.7/site-packages/...
Such a layout can be easily deployed with the below command.
$ appcfg.py update app-engine-project-root
Or tested with App Engine development server.
$ dev_appserver.py app-engine-project-root
UPDATE
Since App Engine Python SDK version 1.9.15 you can use the vendoring mechanism to set up third party libraries. You do not have to create symlinks in your application directory pointing to the Python lib folder anymore.
Create lib directory directly in your application root and tell your app how to find libraries in this directory by means of appengine_config.py file.
from google.appengine.ext import vendor
# Add any libraries installed in the "lib" folder.
vendor.add('lib')
New directory layout follows.
virtual-env-root
.Python
bin
include
lib
app-engine-project-root
lib
app.yaml
appengine_config.py
django-project-root
django-app-root
Use pip with the -t lib flag to install libraries in this directory.
$ pip install -t lib [lib-name]
Or
$ pip install -t lib -r requirements.txt

You cannot - GAE only supports 1.5, and even that is marked as experimental. If you need django 1.7, perhaps you should use Google Compute Engine, which is Google's brand name for virtual machines that you can spool up.
If you are not married to Google App Engine, Heroku supports django 1.7 without issues.
Do you have specific a guide on how to move a Django 1.7 project to
Google Compute Engine? There is a bunch of Google stuff without any
guides on how to make them work.
Here are the steps, but they are the same had you deployed on any other server because GCE just gives you a linux instance:
First, make sure your developer account has a billing method attached to it.
Go to the developer console
Create a new project by clicking on Projects, then Create Project.
Wait as the project is being created (you'll see a progress window on the bottom right of your screen).
Once the project is finished creating, the console will automatically shift to that project's settings:
You can create a new instance, or deploy a ready-made template from the second column. You can see there are popular stacks and software applications for which templates are created.
As there is no django template yet, you will start by creating an instance.
Billing is controlled on a per-project basis, so you'll have enable billing at this point if you haven't done so already.
The next page is where you configure the instance. The fields are self-explanatory. You set the type of machine you like (how many virtual CPUs and memory), where (physically) you prefer the machine to be located, if you want both HTTP and HTTPS ports open, and then a disk image from which the instance will boot:
Once you have configured the machine, it will be brought online booted up and then you'll have access to the terminal via SSH.
From this point forward, you should treat this instance like any linux server. Install whatever you need to make your project work using the normal packaging tools; upload your files, etc.
For Amazon, the process is a bit simpler as there is a large library of AMIs that you can use for a one-click deployment process. AMI is Amazon Machine Image - a template from which you can deploy an instance.
For Heroku, as its a PaaS, you don't have to worry about the hardware components; however as with most PaaS platforms, you don't have write access to the filesystem. So to manage your static assets you have to do some extra work. The easiest option is to create a S3 bucket on Amazon and use that with django-storages. The official django tutorial at heroku suggests the use of dj-static to serve files directly from Heroku. This works fine for testing, but if you want to start uploading files, then you need to handle those correctly.
However, once you sort that out the steps are even simpler:
Pre-requisites:
git
heroku toolbelt
dj-database-url Python package
gunicorn Python package
The basic steps:
Create a git repository (if you have not done already) in your source code directory with git init.
Create a requirements.txt at the root of your project. pip freeze > requirements.txt should do it if you are using a virtual environment. Otherwise, you can create a text file and list the packages you need.
Adjust your settings.py, by adding this line at the very bottom: import dj_database_url
DATABASES['default'] = dj_database_url.config()
Create a Procfile (case is important). This is how you tell Heroku what kind of dyno (process) you need for your application. For django, you need a web dyno so in this file the following line should do: web: gunicorn yourproject.wsgi --log-file -
Create an app on Heroku and deploy. You should run these commands from your source code directory:
heroku create --buildpack https://github.com/heroku/heroku-buildpack-python
heroku addons:add heroku-postgresql:dev
git push heroku master
heroku run python yourproject/manage.py migrate --noinput
heroku run python web/manage.py collectstatic
You only do the first two steps once, then whenever you need to update your application simply git push heroku master to create a new revision on Heroku.

App Engine's Python environment currently knows how to provide Django up to version 1.5 via the libraries: configuration mechanism. This doesn't mean that later versions of Django won't work, only that they aren't yet built in. (I'm not sure why the latest built-in version is 1.5. It may have something to do with AE's historical policy of bundling each supported version of Django with the SDK, which probably needs to be revised to keep the SDK from getting too large.)
You can try to include Django 1.7 with your application files. I haven't tried this with 1.7 specifically yet, but it's worked with previous versions. Some adjustments to sys.path will be needed in your main.py.
Note that there is a limit of 10,000 application files. If you're concerned about this limit, one option is to use Python's zipimport and include Django as a zip archive. https://docs.python.org/2/library/zipimport.html

Using Django on OpenShift

Expanding on this question I am trying to deploy Django on OpenShift but I'm having some problems understanding OpenShift.
I have managed to get as far as setting up a quick app with the git repo https://github.com/openshift/django-example but have the following questions:
Can I develop locally after git cloning to my local? (virtualenv, adding packages)
Packages, what's the deal? local, remote, adding, sycing, virtualenv, git, ...
I came across this line in Nate Aune's PaaS Bakeoff (slide 42) for setup.py and it looks quite useful:
install_requires=open('%s/project.txt' % \
os.environ.get('OPENSHIFT_REPO_DIR', PROJECT_ROOT)).readlines(),
(because I know I can pip freeze > requirments.txt in my virtualenv)
... Is %s/project.txt in wsgi or tthe directory below wsgi? Do I have to set PROJECT_ROOT with some funky os stuff?
EDIT
Basically:
Is it best to ssh into your OpenShift application (lest say you have a dev one) and work there or work off a local copy?
How do you install python packages after you have ssh'ed in to your OpenShift app? (virtualenv)
If you ssh'ed into your OpenShift app do you have to do anything after: creating a project, creating an app (manage.py startapp ...), changing code in your django app
If local is the best option:
How do I use the example locally?
Do I need to setup a virtualenv to work locally?
How do I make sure the python packages django needs are on OpenShift?
How do I add python packages to my OpenShift version (I'm presuming git doesn't do that)

I would suggest developing in a local copy.
In my experience there is no reason to ssh in, unless if you
need to perform one-of operation (migrating databases for example)
The requirements for the openshift app are specified in the setup.py file.
install_requires=['Django>=1.6.0', 'redis>=2.0']
Locally you can of course work in a virtualenv

I was facing a similar situation and found the answer provided by Luis Masuelli to the question posted here very informative. Hope it might help you.