change-tracker

Change tracker

This directory contains an example of how to use the change_tracker rule. The rule will generate a JSON file containing and output like this:

{"digest":"6244db3ebf208f21526de3e458d396e3802eb6903ff8d5911a0a90bb21837a2c","run":["//:deploy"],"tags":["deployable"]}

The digest is a hash of the deps attribute and run is an array containing the targets specified in the run atribute.

The tags come from the tracker_tags attribute of the rule and can contain an arbitrary list of tags. These tags can be used for querying with jq or some other JSON tool after running the diff command bazel run snapshots -- diff --format=json --stderr-pretty $(pwd)/old_tracker.json. This command will output a list of changes in the format below.

[
  {
    "digest": "6244db3ebf208f21526de3e458d396e3802eb6903ff8d5911a0a90bb21837a2c",
    "run": [
      "//:deploy"
    ],
    "tags": [
      "deployable"
    ],
    "label": "//:artifact_change_tracker",
    "change": "changed"
  }
]

When running bazel run snapshots -- collect the snapshots tool run a query against the output group with name change_track_files which is the output group created by change_tracker. It will then aggregate all the files into a single JSON file containing a list of digests and run targets. The ouput will look like the JSON object below.

{
  "labels": {
    "//:artifact_change_tracker": {
      "digest": "6244db3ebf208f21526de3e458d396e3802eb6903ff8d5911a0a90bb21837a2c",
      "run": [
        "//:deploy"
      ],
      "tags": [
        "deployable"
      ]
    }
  }
}