nodes metadata JSON ouput

[crazy-max]

At the moment endpoint, status, flags and platforms outputs are only return for the very first note being registered for the builder.

This PR adds a new output nodes that returns metadata JSON of all registered nodes and also adds new fields available since Buildx 0.9:

[
  {
    "name": "builder-06133552-7a7d-4d4f-a011-fccc08c3ae500",
    "endpoint": "unix:///var/run/docker.sock",
    "driver-opts": [
      "image=moby/buildkit:master",
      "network=host"
    ],
    "status": "running",
    "buildkitd-flags": "--allow-insecure-entitlement security.insecure --allow-insecure-entitlement network.host",
    "buildkit": "81b6ff2",
    "platforms": "linux/amd64,linux/amd64/v2,linux/amd64/v3,linux/386"
  }
]

This change is primarily for future support of appending nodes to a builder, so the output is relevant.

endpoint, status, flags and platforms outputs are deprecated and will be removed in next major release.

[tonistiigi]

I could maybe see status and platforms being a little bit useful in some cases. If the goal is to handle the cases with multiple nodes(not very common in CI) then maybe we could just combine the values for these fields?

[jedevc]

I could maybe see status and platforms being a little bit useful in some cases. If the goal is to handle the cases with multiple nodes(not very common in CI) then maybe we could just combine the values for these fields?

Agreed, especially makes sense for platforms, I like the idea of merging each node's together for this if we can.

[crazy-max]

I could maybe see status and platforms being a little bit useful in some cases. If the goal is to handle the cases with multiple nodes(not very common in CI) then maybe we could just combine the values for these fields?

Agreed, especially makes sense for platforms, I like the idea of merging each node's together for this if we can.

This would not give the expected result as we can define preferred platforms even if those are not supported on specified nodes:

  {
    "nodes": [
      {
        "name": "builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf10",
        "endpoint": "docker-container://buildx_buildkit_builder-ba6a88cb-fe10-4412-876e-66458fe474180",
        "status": "running",
        "platforms": "linux/amd64,linux/amd64/v2,linux/amd64/v3,linux/amd64/v4,linux/arm64,linux/riscv64,linux/ppc64le,linux/s390x,linux/386,linux/mips64le,linux/mips64,linux/arm/v7,linux/arm/v6"
      },
      {
        "name": "aws_graviton2",
        "endpoint": "tcp://***:1234",
        "driver-opts": [
          "cacert=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/cacert_***-1234.pem",
          "cert=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/cert_***-1234.pem",
          "key=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/key_***-1234.pem"
        ],
        "status": "running",
        "platforms": "darwin/arm64*,linux/arm64*,linux/arm/v5*,linux/arm/v6*,linux/arm/v7*,windows/arm64*"
      },
      {
        "name": "linuxone_s390x",
        "endpoint": "tcp://***:1234",
        "driver-opts": [
          "cacert=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/cacert_***-1234.pem",
          "cert=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/cert_***-1234.pem",
          "key=/home/runner/.docker/buildx/creds/builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1/key_***-1234.pem"
        ],
        "status": "running",
        "platforms": "linux/s390x*"
      }
    ],
    "name": "builder-13dbff8e-3be6-4024-9aa5-2c75782f1cf1",
    "driver": "remote"
  }

For example here aws_graviton2 supported platforms are:

time="2022-09-19T21:12:20Z" level=info msg="found worker \"klrqif3uuxy84t69eo3eef89n\",
  labels=map[org.mobyproject.buildkit.worker.executor:oci
    org.mobyproject.buildkit.worker.hostname:7c099955516d
    org.mobyproject.buildkit.worker.network:host
    org.mobyproject.buildkit.worker.oci.process-mode:sandbox
    org.mobyproject.buildkit.worker.snapshotter:overlayfs
  ],
  platforms=[linux/arm64 linux/arm/v7 linux/arm/v6]"

But I define the following ones as preferred:

      -
        name: Set up Docker Buildx
        uses: crazy-max/docker-setup-buildx-action@append
        with:
          driver: remote
          endpoint: docker-container://buildx_buildkit_${{ steps.builder.outputs.name }}0
          append: |
            - name: aws_graviton2
              endpoint: tcp://${{ secrets.AWS_ARM64_HOST }}:1234
              platforms: darwin/arm64,linux/arm64,linux/arm/v5,linux/arm/v6,linux/arm/v7,windows/arm64
            - name: linuxone_s390x
              endpoint: tcp://${{ secrets.LINUXONE_S390X_HOST }}:1234
              platforms: linux/s390x

See #165 and https://github.com/crazy-max/docker-setup-buildx-action/blob/append/docs/advanced/append-nodes.md about the append input

[crazy-max]

As discussed keep platforms output but return preferred ones if set or all available.