Issue

My Python dependencies are being reinstalled fresh every deploy.

Resolution

Issue status: FIXED

Context

A regression was introduced recently while fixing an unrelated bug, one that caused apps to crash if a new version of SQLITE was made available on the stack.

The regression caused the Python Buildpack to re-install all python packages from scratch after installing SQLITE.

This regression has now been fixed so that installing SQLITE does not cause a cache refresh. The Python Buildpack will now compare your cached requirements.txt file to your current, and if no changes are present, install your cached dependencies.

How to tell if your buildpack is installing from cache

Note: Because this fix involves an update to your build cache, you will see the corrected behavior on the second redeploy.

If your dyno has cycled since the bugfix was released, you may only need one redeploy.

To trigger two redeploys via the command line:

# first deploy updates the build cache
git commit --allow-empty -m "Trigger rebuild"
git push heroku master -a app-name

# second deploy uses the updated cache for dependencies
git commit --allow-empty -m "Trigger rebuild"
git push heroku master -a app-name

On the second deploy, you should cause build install dependencies from the build cache.