chore: add docker-compose local dev env

[iwpnd]

This PR adds a local development environment using docker compose as proposed here that makes local development a breeze, even if you're unfamiliar with the project.

1. clone the repository
2. docker compose up
3. run test suite

   RUN_POSTGIS_TESTS=yes RUN_REDIS_TESTS=yes PGSSLMODE=disable PGSSLKEY="" PGSSLCERT="" PGSSLROOTCERT="" PGHOST=localhost PGPORT=5432 PGDATABASE=tegola PGUSER=postgres PGPASSWORD=postgres PGUSER_NO_ACCESS=tegola_no_access go test  ./... -v

4. docker compose down

[coveralls]

Pull Request Test Coverage Report for Build 905eed645-PR-840

• 0 of 0 changed or added relevant lines in 0 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage remained the same at 45.114%

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Totals
Change from base Build 21da05b0a:	0.0%
Covered Lines:	5485
Relevant Lines:	12158

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💛 - Coveralls

[ARolek]

I have 2 minor requests:

• add a docker-compose.env file with the various env vars that you have in the run command.
• Add the docker-compose commands to the readme

That you for this addition!

[iwpnd]

@ARolek thank you for the review

add a docker-compose.env file with the various env vars that you have in the run command.

You'd have to check-in an docker-compose.env.example file and tell the user to rename it. This would also only allow me to do something like this in the docker-compose.yml:

    healthcheck:
      test: ["CMD-SHELL", "pg_isready -U ${PGUSER} -d ${PGDATABASE}"]

It would not load the .env environment variables into our local environment so go test can use them. For this to work I'd have to refactor the test with a function to load the docker-compose.env or something. So the command to run the local test would still need whatever environment variables tegola uses in tests.

Add the docker-compose commands to the readme

Once the above is solved :)