Add command pack manifest annotate to update information on manifest list

[jjbustamante]

Context

We've been working on the idea to add multi-arch support on CNB. A mentorship project was created on LFX and this feature is part of the efforts to build the Minimal Viable Product (MVP) during the program duration.

More information can be found:

• Notes
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Description

When a manifest list is created using the pack manifest create command it will be saved in the local daemon, sometimes it is required to add the platform information os, architecture, or variant. A new command to modify a manifest list (Image index) and update the platform information for an image included in the manifest list.

Proposed solution

A new feature on Pack can be implemented to help our users. The feature is inspired by the similar functionality in docker or podman

pack manifest annotate [OPTIONS] <manifest-list> <manifest> 

Add additional information to a local image manifest

  options:
      --arch string           Set the architecture
      --os string              Set the operating system
      --variant string       Set the architecture variant

Example

Let's suppose we have a manifest list saved in the docker daemon with the following information

{
  "schemaVersion": 2,
  "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
  "manifests": [
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "size": 940,
      "digest": "sha256:87a832fd6a8d6995d336c740eb6f3da015401a6e564fcbe95ee1bf37557a8225",
      "platform": {
        "architecture": "",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "size": 1148,
      "digest": "sha256:670d62fbee841d256a706801a03be9c84d37fc2cd6ef7538a7af9985c3d2ed8b",
      "platform": {
        "architecture": "",
        "os": "windows"
      }
    }
  ]
}

As we can see, the manifests included in this list do not have architecture defined.

Executing

 pack manifest annotate  --arch amd64 cnbs/sample-package:hello-multiarch-universe cnbs/sample-package:hello-universe

It should output:

{
  "schemaVersion": 2,
  "mediaType": "application/vnd.docker.distribution.manifest.list.v2+json",
  "manifests": [
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "size": 940,
      "digest": "sha256:87a832fd6a8d6995d336c740eb6f3da015401a6e564fcbe95ee1bf37557a8225",
      "platform": {
        "architecture": "amd64",
        "os": "linux"
      }
    },
    {
      "mediaType": "application/vnd.docker.distribution.manifest.v2+json",
      "size": 1148,
      "digest": "sha256:670d62fbee841d256a706801a03be9c84d37fc2cd6ef7538a7af9985c3d2ed8b",
      "platform": {
        "architecture": "",
        "os": "windows"
      }
    }
  ]
}

Describe alternatives you've considered

Additional context

• This feature should be documented somewhere