October 04, 2014
In a standard single application Heroku deployment, the app name is usually implicit if your
working directory is a Heroku app with your Heroku repository. Once you
introduce another deployed environment, like a staging environment, you need to
specify the app name, e.g.
myappname-staging. So that instead
of running something like:
You’ll need to run:
heroku config --app myappname-staging
Some extra keystrokes but nothing too horrible.
For our standard Django deployment there are a few minimum tasks that need to be run as part of a deployment, including updating dependencies, collecting static files, and making database changes. The standard Heroku Python buildback takes care of the first two, so we just need to make database changes. It’s one extra step, but it’s one extra to remember every time.
Instead, the helper script here wraps several common tasks, like those associated with deployment, and provides consistent environment naming, across projects, for interacting with Heroku deployments.
Instead of pushing to the specified Git remote and then executing commands against the specified app like so:
git push heroku-staging master heroku run python myapp/manage.py migrate --app=myapp-name
It’s one environment based command:
./heroku staging deploy
And this is similar for executing any basic Heroku CLI command. Updating configuration:
heroku config:set MYVAR=True --app=myapp-name
./heroku production config:set MYVAR=True
This last command isn’t such a big win in saving you from typing, but it does introduce consistency, focused on environment rather than app name. Leading with the environment name makes it very clear where your command is targeted.
Since the particular focus here is for Django projects, the script has a helper for running Django management commands. Instead of:
heroku run python myapp/manage.py custom_management_command --app=myapp-name
The script environment handling gets us to this:
./heroku production run python myapp/manage.py some_management_command
And a simple command addition let’s us replace that boilerplate.
./heroku production dj some_management_command
With multiple environments it makes sense to adopt Heroku’s pipelines feature for deployment. This feature allows you to deploy from one Heroku environment to another by copying the entire slug. This means full replication of course and very quickly. We can wrap this up in the script, too.
In the workflow we have set up, the user should be shown the environment diff first, then verify that they do want to promote, and then promote the staging environment. Instead of:
heroku pipeline:diff --app=myappname-staging heroku pipeline:promote --app=myappname-staging heroku run python afficon/manage.py syncdb --noinput --app=myappname heroku run python afficon/manage.py migrate --app=myappname
This can be run using:
The script will first take a diff and ask for confirmation, then promote the slug, and lastly run any commands necessary to complete deployment.
You can grab a copy of this script (which requires modification, of course) from the embedded gist below. It’s also included in my cookiecutter Django project template.
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