Enhancements for compose up command. (--remove-orphans)

[fhke]

This PR contains the following updates to the compose up command:

• Idempotency: rather than failing when a container already exists and has been created by compose, recreate the container. This allows users to iterate rapidly with compose up, rather than deleting & recreating their compose stack to effect changes.
• Add support for --remove-orphans flag: remove containers for services not defined in the Compose file. This fixes nerdctl compose up support for remove-orphans #342

Signed-off-by: fergal kearns fhke@protonmail.com

[AkihiroSuda]

This operation might be slow and should be called only when RemoveOrphans is true

[fhke]

Hi @AkihiroSuda, I appreciate this operation could introduce additional delays into the compose up workflow, but without performing it we cannot warn users who have not specified --remove-orphans that orphaned containers exist:

	if numOrphans > 0 {
		if uo.RemoveOrphans {
			if err := c.downContainers(ctx, orphans, true); err != nil {
				return fmt.Errorf("error removing orphaned containers: %s", err)
			}
		} else {
			logrus.Warnf("%d orphaned containers exist. Run with --remove-orphans to remove them.", numOrphans)
		}
	}

This would be a deviation from the behaviour of docker-compose, which prints a similar warning.

We can probably reduce the time taken without losing this error message by comparing the total number of containers in the parsedServices slice with the total number of running containers in the compose project; this would remove the requirement to call the .Labels() method for each container:

	for _, container := range containers {
		containerLabels, err := container.Labels(ctx)
		if err != nil {
			return false, err
		}
		if name == containerLabels[labels.Name] {
			// container exists
			return true, nil
		}
	}

Please let me know if you're happy with that approach, and I'll make the changes accordingly.

[AkihiroSuda]

This would be a deviation from the behaviour of docker-compose, which prints a similar warning.

I think this difference is acceptable.

[AkihiroSuda]

ping @fhke

[fhke]

Hey @AkihiroSuda, apologies for the delay. I've updated this PR with the requested changes.

[AkihiroSuda]

Thanks