feat: support ordered container start (#321)

[Abhishek9639]

Description

What does this PR do?

This PR adds support for ordered container start by mapping the Score spec's before field to Docker Compose's depends_on. When a container declares before: containers: [main], the generated compose output will have main with a depends_on entry pointing back to that container.

The ready condition is mapped as follows:

• started (default) -> service_started
• complete -> service_completed_successfully
• healthy -> service_healthy

Validation is added during score-compose generate to catch:

• Cyclic dependencies between containers
• References to containers that don't exist in the workload
• Containers referencing themselves

For ready: healthy, a warning is emitted if no readiness or liveness probe is defined. This keeps generation working while letting users know they may need to add a healthcheck. Waiting for @chris-stephenson's feedback on whether this should be an error instead.

Uses the score-go ordered-containers branch as instructed by @mathieu-benoit.

Fixes #321

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• I've signed off with an email address that matches the commit author.

[Abhishek9639]

Hi @mathieu-benoit,
This is ready for review.

Quick summary of what's here:

• Inversion of before -> depends_on with condition mapping (started, complete, healthy).
• Validation during generate for cycles, unknown container refs, and self-references.
• Using the score-go ordered-containers branch as you suggested.

One open point: for ready: healthy without a healthcheck probe, I went with emitting a warning for now instead of failing. Happy to change this based on @chris-stephenson's feedback.

Let me know if anything needs adjusting.
Thanks

[Abhishek9639]

Moved this back to draft while waiting for @chris-stephenson's feedback on the ready: healthy behavior.

Also @mathieu-benoit, could you please re-assign me to this PR? I don't have write permissions to set the assignee myself.
Thanks

[Abhishek9639]

@mathieu-benoit @chris-stephenson
The requested change is pushed! ready: healthy without a healthcheck probe is now a hard failure, and I've also added a test case for it.

I've marked the PR as ready for review.
Let me know if anything else is needed.
Thanks

[mathieu-benoit]

Wonderful, thanks @Abhishek9639!

@chris-stephenson, before merging score-go and then this one, let's make sure that the Spec is LGTMed before, @Abhishek9639 brought a good there question, let's confirm there please: score-spec/spec#136 (comment).