Setup a docker-compose override file.

[tecnobrat]

This moves the "secrets" into a docker-compose override. This allows the docker-compose file to be committed, and we have an example override.

Also adds the new bootstrap env vars so that you can launch cog without any configuration at all.

[tecnobrat]

Perhaps these ports can be in the base docker-compose

[imbriaco]

Yeah, I think they make sense in the base because they match the defaults from Cog.

[imbriaco]

Thanks for the PR, I like the direction!

One behavior that we have with the existing docker-compose.example.yml that I'd like to keep is that we only require users to set a couple of environment variables if they just want to kick the tires with a test environment. I think we can keep that behavior while still adding the override file which I quite like by making the defaults for SLACK_API_TOKEN and the *_URL_HOST variables use environment variable interpolation in the override file for their defaults.

I also think we should use default values for the COG_BOOTSTRAP_* variables that mirror what Cog does by default as much as possible. Perhaps:

COG_BOOTSTRAP_USERNAME=admin
COG_BOOTSTRAP_PASSWORD=changeme
COG_BOOTSTRAP_EMAIL_ADDRESS=cog@localhost
COG_BOOTSTRAP_FIRST_NAME=Cog
COG_BOOTSTRAP_LAST_NAME=Administrator

What do you think?

[tecnobrat]

@imbriaco made those changes.

Also tweaked the hostnames to be cog and postgres instead of aliasing to localhost, which has the potential to cause some significant issues.