The default run images MUST be encoded in the builder and not in the pack CLI config

[sclevine]

New config.toml:

default-stack-id = "io.buildpacks.stacks.bionic"

[[stacks]]
  id = "io.buildpacks.stacks.bionic"
  build-image = "packs/build"
  run-images = ["packs/run", "gcr.io/packs/run"]

[[builders]]
  image = "packs/sample"
  run-images = ["example.com/packs1/run", "example.com/packs2/run", "gcr.io/packs2/run",]

Need new command:

pack configure-builder <builder> -r example.com/packs1/run -r example.com/packs2/run

NOTE: this replaces the run image list every time

For pack inspect-remote-builder:

...
Run images:
  example.com/packs1/run (local)
  example.com/packs2/run (local)
  gcr.io/packs2/run (local)
  packs/run
  gcr.io/packs/run

Notes

• The stacks list in config.toml MUST only be used in pack create-builder, and not in pack build.
• The builders list in config.toml MUST only be used in pack build (or pack inspect-remote-builder), and not in pack create-builder.
• -r is option, no -r flags means no run images. No configuration removes the entry for the builder in config.toml.
• The final list, searched in order, would be:
  ["example.com/packs1/run", "example.com/packs2/run", "gcr.io/packs2/run", "packs/run", "gcr.io/packs/run"]

Acceptance Criteria
Given The above config.toml file without the builders section
When I run pack build gcr.io/user/myapp --builder packs/sample
Then gcr.io/packs/run is used to export the final image

Given The above config.toml file with the builders section
When I run pack build gcr.io/user/myapp --builder packs/sample
Then gcr.io/packs2/run is used to export the final image

Given The above config.toml file with the builders section
When I run pack build example.com/user/myapp --builder packs/sample
Then example.com/packs1/run is used to export the final image

[ameyer-pivotal]

A couple of questions:

• How would users remove the set of override run images for a builder? A new command?
• Should we provide a way to list the set of builders that have overrides?

[sclevine]

Updated OP.

[jchesterpivotal]

How we think we will work through this:

• update create-builder to add current stack's run images to builder metadata
• update build (and by implication run) to use the run image metadata injected by create-builder
• add inspect-remote-builder to list run images baked into builder
• update inspect-remote-builder to list run images from config.toml for builder
• add configure-builder to update config.toml with run images for builder, account for these run images during build
• update published builder to have new metadata (packs/samples)