[BUG] `service "test-abc" has neither an image nor a build context specified: invalid compose project`

[stdedos]

Description

version: "3.9"

services:
  nginx:
    build:
      context: ../
      dockerfile: .gitlab/nginx/Dockerfile
    ports:
      - "80:80"
    cap_add:
      - NET_ADMIN

  abc:
    image: registry/abc:latest
    ports:
      - "127.0.0.1:1234:1234"

  moar_underscored_services:
    image: registry/moar_underscored_services:latest
    ports:
      - "127.0.0.1:9012:9012"

  def:
    image: registry/def:${DEF_TAG}
    ports:
      - "127.0.0.1:5678:5678"

  moar-dashed-services:
    image: registry/moar-dashed-services:latest
    ports:
      - "127.0.0.1:3456:3456"

  test-abc:
    image: ${ABC_IMAGE}
    depends_on:
      - abc
      - more_underscored_services
    entrypoint: ["npm", "run", "test"]

  test-def:
    image: ${DEF_IMAGE}
    depends_on:
      - more_underscored_services
      - def
      - moar_underscored_services
    entrypoint: ["npm", "run", "test"]

with this file, DEF_TAG=$DOCKER_TAG_NAME DEF_IMAGE=$REGISTRY:$CI_COMMIT_REF_SLUG docker-compose -f path/.to/docker-compose.yml run test-def happily compiles.

However, docker compose V2 (aliased via docker-compose) gives:

time="2023-10-12T12:29:46Z" level=warning msg="The \"ABC_TAG\" variable is not set. Defaulting to a blank ....
service "test-abc" has neither an image nor a build context specified: invalid compose project

In case it is not obvious, test-abc is never called in this invocation.

Is that expected?

Steps To Reproduce

No response

Compose Version

docker-cli-compose	2.17.3-r7	URL	Apache-2.0	v3.18	community	x86_64	Jake Buchholz Göktürk	2023-10-12 14:14:03

In Alpine

### Docker Environment

_No response_

### Anything else?

_No response_

[ndeloof]

Right, Docker Compose v1 is more lazy validating your compose file, while compose v2 does a full model validation (handled by compose-go library) before running a command, even the latter doesn't actually require this resource. A possible workaround is to declare a default value for such variables: image: ${ABC_IMAGE:-none}

[ndeloof]

Bypassing consistency check for unselected resources would have a significant impact on the compose-go parser codebase, with risk to introduce regressions. So I prefer we close this issue as "not planned" considering in most cases fixing the compose model for unused resources to have "reasonable defaults" is an acceptable workaround

[stdedos]

So I prefer we close this issue as "not planned"

Then please do so :pray: Don't close it as "completed"