Rockcraft extension 'flask-framework'

The flask-framework Rockcraft extension includes configuration options customised for a Flask application. This document describes all the keys that a user may interact with.

rockcraft.yaml > parts > flask-framework/dependencies: > stage-packages

You can use this key to specify any dependencies required for your Flask application. For example, below we use it to specify libpq-dev:

parts:
    flask-framework/dependencies:
      stage-packages:
        # list required packages or slices for your flask application below.
        - libpq-dev

rockcraft.yaml > parts > flask-framework/install-app: > prime

You can use this key to specify the files to be included in your rock upon rockcraft pack, in flask/app/<filename> notation. For example:

parts:
  flask-framework/install-app:
    prime:
       - flask/app/.env
       - flask/app/app.py
       - flask/app/webapp
       - flask/app/templates
       - flask/app/static

Some files, if they exist, are included by default. These include: app, app.py, migrate, migrate.sh, migrate.py, static, templates.

Regarding the migrate.sh file:

If your app depends on a database it is common to run a database migration script before app startup which, for example, creates or modifies tables. This can be done by including the migrate.sh script in the root of your project. It will be executed with the same environment variables and context as the Flask application.

If the migration script fails, the app won’t be started and the app charm will go into blocked state. The migration script will be run on every unit and it is assumed that it is idempotent (can be run multiple times) and that it can be run on multiple units at the same time without causing issues. This can be achieved by, for example, locking any tables during the migration.