Docker tests in CI

[Stebalien]

Since the transition to CircleCI, we've lost our docker tests. We should enable them in CircleCI (not sure if we can just flip a switch or something...).

[Stebalien]

@lanzafame (or @mburns?) would one of you have time to get docker image testing working in CircleCI? We can either use our docker sharness tests or do something custom.

[Stebalien]

We'll need to take a look at https://circleci.com/docs/2.0/building-docker-images/ and adapt the tests for this.

1. We can't mount in CircleCI.
2. Only docker containers can talk to each other.

[Stebalien]

We'll need to modify:

• test/sharness/t0301-docker-migrate.sh
  • We can't mount. We'll need to create a dummy container as described in https://circleci.com/docs/2.0/building-docker-images/.
  • The docker container can't talk to network services running inside the test. Specifically, it can't talk to socat. We'll want to run a special socat container (alpine/socat?) to serve the fake HTTP response.
• .circleci/config.yml
  • We'll need to modify the sharness job's steps to invoke setup_remote_docker.