Continuous deployment of a Django app from Travis CI to PythonAnywhere
This post describes the configuration of a continuous deployment pipeline that deploys a Django project from GitHub via Travis CI to PythonAnywhere.
All code samples come from a pet project of mine: Unkenmathe (GitHub repository).
Please note that this is no introduction to Travis CI, PythonAnywhere nor Git.
Here are the steps that I take.
1. Deploy Django project
PythonAnywhere's guide for Deploying an existing Django project on PythonAnywhere explains everything to manually set up the web app.
For reference, the Unkenmathe code is checked out to
/var/www/sites/unkenmathe.de
and the virtual environment lives at
~/.virtualenvs/unkenmathe.de/
2. Prepare Git push deployment
PythonAnywhere has a comprehensive guide to set up Git push deployments.
My bare repository is located at
~/bare-repos/unkenmathe.git
The post-receive hook looks like this:
# ~/bare-repos/unkenmathe.git/hooks/post-receive
#!/bin/bash
BASE_DIR=/var/www/sites/unkenmathe.de
PYTHON=$HOME/.virtualenvs/unkenmathe.de/bin/python
PIP=$HOME/.virtualenvs/unkenmathe.de/bin/pip
MANAGE=$BASE_DIR/manage.py
echo "=== configure Django ==="
export DJANGO_SETTINGS_MODULE=config.settings.production
echo "=== create base directory ==="
mkdir -p $BASE_DIR
echo "=== checkout new code ==="
GIT_WORK_TREE=$BASE_DIR git checkout -f
echo "=== install dependencies in virtual environment ==="
$PIP install -q -r $BASE_DIR/requirements/production.txt
echo "=== collect static files ==="
$PYTHON $MANAGE collectstatic --no-input
echo "=== update database ==="
$PYTHON $MANAGE migrate --no-input
3. Custom deployment with Travis CI
I set up the repository in Travis CI for automatic builds on pull requests and branch pushes. In order to deploy to PythonAnywhere, I use Travis's Custom deployment.
All Travis related files live in the .travis subdirectory of the Django project. This is of course completely arbitrary.
~ $ cd ~/code/unkenmathe/
unkenmathe $ mkdir .travis
unkenmathe $ cd .travis
Create SSH keys
git push uses SSH, so I need a pair of SSH keys.
.travis $ ssh-keygen -t rsa -b 4096 -C 'hallo@example.com' -f deploy_key
Copy the public key to the PythonAnywhere account (see PythonAnywhere: SSH access).
.travis $ ssh-copy-id -i deploy_key flowfx@ssh.pythonanywhere.com
Encrypt SSH key and add it to the repository
Travis offers a tool to encrypt files that allows to add the SSH private key to the Git repository. See Encrypting files for a complete how-to.
First, I encrypt the deploy key,
.travis $ travis login
.travis $ travis encrypt-file deploy_key --add
then add it to the Git repository.
.travis $ git add deploy_key.enc
Last, I make sure the decrypted key is never pushed to the public GitHub repository:
unkenmathe $ echo 'deploy_key' >> .gitignore
Configure Travis CI
A simplified .travis.yml configuration file (here the one used for Unkenmathe) looks like this. The before_install part is added automatically by the travis encrypt-file deploy_key --add command. The ssh_known_hosts line is also required for push deployment with Git/SSH.
Hopefully, the rest is documented sufficiently by the comments.
# .travis.yml
language: python
cache: pip
python:
- 3.6
addons:
# add PythonAnywhere server to known hosts
ssh_known_hosts: ssh.pythonanywhere.com
before_install:
# decrypt ssh private key
- openssl aes-256-cbc -K $encrypted_xxxxxxxxxxxx_key -iv $encrypted_xxxxxxxxxxxx_iv -in .travis/deploy_key.enc -out deploy_key -d
install: pip install -r requirements/testing.txt
script:
# run test suite
- pytest --cov
after_success:
# start ssh agent and add private key
- eval "$(ssh-agent -s)"
- chmod 600 deploy_key
- ssh-add deploy_key
# configure remote repository
- git remote add pythonanywhere flowfx@ssh.pythonanywhere.com:/home/flowfx/bare-repos/unkenmathe.git
# push master branch to production
- git push -f pythonanywhere master
# reload PythonAnywhere web app via the API
- python .travis/reload-webapp.py
after_deploy:
# update coveralls.io
- coveralls
notifications:
# spare me from email notifications
email: false
Reload web app
The after_success step includes a call to .travis/reload-webapp.py, which is a Python script that reloads the web app via the PythonAnywhere API. This is more or less copied directly from the documentation.
# .travis/reload-webapp.py
"""Script to reload the web app via the PythonAnywhere API.
"""
import os
import requests
my_domain = os.environ['PYTHONANYWHERE_DOMAIN']
username = os.environ['PYTHONANYWHERE_USERNAME']
token = os.environ['PYTHONANYWHERE_API_TOKEN']
response = requests.post(
'https://www.pythonanywhere.com/api/v0/user/{username}/webapps/{domain}/reload/'.format(
username=username, domain=my_domain
),
headers={'Authorization': 'Token {token}'.format(token=token)}
)
if response.status_code == 200:
print('All OK')
else:
print('Got unexpected status code {}: {!r}'.format(response.status_code, response.content))
Set environment variables
To make all this actually work, you need to set some environment variables in the Travis project settings. Namely PYTHONANYWHERE_DOMAIN, PYTHONANYWHERE_USERNAME and PYTHONANYWHERE_API_TOKEN.
Also, don't forget to set DJANGO_SECRET_KEY!
Summary
These are the resources you need:
PythonAnywhere
- Deploying an existing Django project on PythonAnywhere
- Git push deployments
- SSH Access
- PythonAnywhere API
Travis CI
Future
I need to look into Travis's Script deployment which looks like a much cleaner way to run the deployment commands.
Comment!
If you find the one error that I missed, please tell me about it!
Updates
- 5/9/2017: used Unkenmathe as example project, formatting.