Allow set container_image labels by json file

[bozaro]

PR Type

What kind of change does this PR introduce?

• Bugfix
• Feature
• Code style update (formatting, local variables)
• Refactoring (no functional changes, no api changes)
• Build related changes
• CI related changes
• Documentation content changes
• Other... Please describe:

What is the new behavior?

Allow set docker labels by .json file.

Does this PR introduce a breaking change?

• Yes
• No

[uhthomas]

Is there an issue open where this feature has been discussed? Could you explain why this may be useful?

[bozaro]

Is there an issue open where this feature has been discussed?
No.

Could you explain why this may be useful?
We use file for labels in two places:

• set Docker labels for image garbage collector policy (we have differ policy for master and feature-branches. Branch type passed by stable stamping variables);
• set marker for "upload if not uploaded yet" logic.

Little bit about "upload if not uploaded yet" workflow:

• we check image in docker registry with upload marker (some uniuqe for build value) and return passed upload marker if image is not uploaded or image marker from uploaded image;
• upload marker passed to labels;
• rule makes push to registry.

As a result, we get the following effect:

• initially image will be upload to registry;
• if image already in registry, we got CACHE HIT (same image and upload marker) and push step will be skipped without downloading all layers to worker;
• if image was remove from registry by GC, we got CACHE MISS (same image but new upload marker) and it will be upload.

[github-actions]

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[bozaro]

Changes:

• rebased to master;
• use labels_file attribute instead of reusing label_files attribute.