Taskcluster views.json proposal

example-views.json

{
  "taskGroupId": "<taskGroupId>",
  "views": [
    {
      "type": "subtask",
      "tasks": ["<task id>", "<task id>", "..."],
      "context": {
        "description": "Linux64 opt Mochitest",
        "symbol": "M",
        "platform": "linux64/opt",
      },
    },
    {
      "type": "subtask",
      "tasks": ["<task id>", "<task id>", "..."],
      "context": {
        "description": "Windows10 64 opt Mochitest",
        "symbol": "M",
        "platform": "windows10-64/opt",
      },
    },
    {
      "type": "taskcluster-unit",
      "tasks": ["<task id>"],
      "context": {
        "description": "set allowed key (twice)",
        "format": "tap",
        "artifact": "report.tap",
      },
    },
    {
      "type": "taskcluster-unit",
      "tasks": ["<task id>"],
      "context": {
        "description": "set disallowed key",
        "format": "tap",
        "artifact": "report.tap",
      },
    },
  ],
}

For the record I think a separate manifest (e.g views.json) would be fine to have as a separate artifact. But using my earlier example in the first comment, treeherder could theoretically group all tasks that have the same "symbol" (and platform). In that case I don't think a separate artifact would be necessary.

I guess if there's additional metadata that only applies to the parent task, defining that in task-graph.json would be clunky, and at that point a separate manifest/artifact might be better. But there's a chance the two problems we're trying to solve are different enough from one another that we're forcing round and square pegs into a triangular hole. (I do agree we should at least try to solve them both in a generic way)