Thanks for your contribution, @mmusenbr! I wonder why this test has not failed. I see during the refactor this was omitted but would be nice to have a test to make sure this is not happening again.

Hi @eddumelendez , I need to answer why ComposePassthroughTest is passing with two aspects:

• Running via ComposeContainer does not seem to need all the details set, as is uses the information from the COMPOSE_PROJECT_NAME

For example having the following yaml:

services:
  redis:
    image: redis
    ports:
      - ${REDIS_PORT}

And then running:
COMPOSE_PROJECT_NAME=randprojname REDIS_PORT=8272 docker compose -f compose.yml up
and then:
COMPOSE_PROJECT_NAME=randprojname docker compose -f compose.yml down
works just with a warning: WARN[0000] The "REDIS_PORT" variable is not set. Defaulting to a blank string.

Whereas running both commands without COMPOSE_PROJECT_NAME, the down command fails with 1 error(s) decoding: * 'services[redis].ports[0]' expected a map, got 'string'.

So, even with this yaml DockerComposePassthroughTest would pass, BUT not ComposePassthroughTest

• Additionally it seems to depend what is substituted to trigger a failure. The used definition in the tests DockerComposePassthroughTest and ComposePassthroughTest is v2-compose-test-passthrough.yml which 'only' substitutes an ENV variable. If this is not substituted, it is not enough to bring docker compose to report an error.

For example having the following yaml:

services:
  redis:
    image: redis
    environment:
      test=${REDIS_PORT}

And running WITHOUT COMPOSE_PROJECT_NAME the commands:
REDIS_PORT=8272 docker compose -f compose.yml up
and then:
docker compose -f compose.yml down
it succeeds and only a warning is printed again.

I have added two tests, as described above, the ComposeContainerPortViaEnvTest would also not fail with the current code, as only the warning is visible in the logs, but stopping works fine. But DockerComposeContainerPortViaEnvTest is the one, which would fail now, but is fixed with this PR.

Thanks for your contribution and detailed explanation, @mmusenbr !