Merge targets from multiple JSON files

[felipecrs]

The goal:

$ cat <<'EOF' > docker-bake.json
{
    "target": {
        "default": {
            "context": "."
        }
    }
}
EOF

$ cat <<'EOF' > docker-bake.override.json
{
    "target": {
        "default": {
            "tags": [
                "test123"
            ]
        }
    }
}
EOF

$ docker buildx bake -f docker-bake.json -f docker-bake.override.json --print
{
    "target": {
        "default": {
            "context": ".",
            "dockerfile": "Dockerfile",
            "tags": [
                "test123"
            ]
        }
    }
}

But instead, it fails with:

$ docker buildx bake -f docker-bake.json -f docker-bake.override.json --print
docker-bake.override.json:2
--------------------
   1 |     {
   2 | >>>     "target": {
   3 |             "default": {
   4 |                 "tags": [
--------------------
error: docker-bake.override.json:2,5-13: Duplicate argument; Argument "target" was already set at docker-bake.json:2,5-13

[tonistiigi]

Updated title as this should work for hcl/compose already. At least there is tested https://github.com/docker/buildx/blob/master/bake/hcl_test.go#L257

[crazy-max]

@tonistiigi Yes I can confirm:

$ cat <<'EOF' > docker-bake.hcl
target "default" {
  context = "."
}
EOF

$ cat <<'EOF' > docker-bake.override.json
target "default" {
  tags = ["test123"]
}
EOF

$ docker buildx bake -f docker-bake.hcl -f docker-bake.override.hcl --print
{
  "group": {
    "default": [
      "default"
    ]
  },
  "target": {
    "default": {
      "context": ".",
      "dockerfile": "Dockerfile",
      "tags": [
        "test123"
      ]
    }
  }
}

[vrslev]

@crazy-max This doesn't work with more than two files:

docker buildx bake  -f bake1.json -f bake2.json -f ./docker-bake.hcl  --print
[+] Building 0.0s (0/0)                                                                                                                   
bake2.json:2
--------------------
   1 |     {
   2 | >>>   "target": {
   3 |         "worker": {
   4 |           "tags": ["username/app:pr-80"],
--------------------
error: bake2.json:2,3-11: Duplicate argument; Argument "target" was already set at bake1.json:2,3-11, and 1 other diagnostic(s)