In process_emails_from_sqs, require that a path to the healthcheck file
is set. For local development, place this at tmp/healthcheck.json, in a
new temporary directory for local development files.
Silk is a live profiling and inspection tool for Django, suitable for
local development. It is disabled when DEBUG=False. It is also disabled
when running tests, since it adds database queries for writing profile
data to the database.
* Remove the apt cache after installing
* Don't create pip caches
* Sync .dockerignore with .gitignore files, except for frontend/out,
which is needed for build