Add support for automatic opencontainer labels

[codrut-fc]

Adding support for automatically setting opencontainers labels as default. Also, now there is a way to turn off automatic labeling.

It's documented here:

• https://github.com/opencontainers/image-spec/blob/master/annotations.md#pre-defined-annotation-keys

Using -e PLUGIN_AUTO_LABEL=false:

docker run --rm \
  -e PLUGIN_AUTO_LABEL=false  \
  -e PLUGIN_TAG=latest  \
  -e PLUGIN_REPO=octocat/hello-world  \
  -e DRONE_COMMIT_SHA=d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab \
  -v $(pwd):$(pwd) \
  -w $(pwd) \
  --privileged \
  plugins/docker --dry-run

+ /usr/local/bin/docker build \
  --rm=true \
  -f Dockerfile \
  -t d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab \
  . \
  --pull=true

With -e PLUGIN_AUTO_LABEL=true, DRONE_REMOTE_URL, and DRONE_REPO_LINK:

docker run --rm \
  -e PLUGIN_AUTO_LABEL=true \
  -e DRONE_REMOTE_URL=https://github.com/octocat/hello-world.git \
  -e DRONE_REPO_LINK=https://github.com/octocat/hello-world \
  -e PLUGIN_TAG=latest \
  -e PLUGIN_REPO=octocat/hello-world \
  -e DRONE_COMMIT_SHA=d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab \
  -v $(pwd):$(pwd) \
  -w $(pwd) \
  --privileged \
  plugins/docker \
  --dry-run

+ /usr/local/bin/docker build \
  --rm=true \
  -f Dockerfile \
  -t d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab \
  . \
  --pull=true \
  --label org.opencontainers.image.created=2021-01-11T17:28:58Z \
  --label org.opencontainers.image.revision=d8dbe4d94f15fe89232e0402c6e8a0ddf21af3ab \
  --label org.opencontainers.image.source=https://github.com/octocat/hello-world.git \
  --label org.opencontainers.image.url=https://github.com/octocat/hello-world

[bradrydzewski]

lets simplify things by removing the deprecated labels entirely and only using the new labels going forward. I would then recommend we use a boolean flag to disable automatic labeling, perhaps auto_label: true|false where the value defaults to true (since this is the current behavior).

[codrut-fc]

All done @bradrydzewski

[codrut-fc]

You might want to restart CI, looks like it reached docker hub's api rate limit...

[bradrydzewski]

@tboerger can you confirm that label_schema values should be ignored if the user sets auto_label: false? This operation is wrapped by if build.AutoLabel { ... and I was wondering if it should be moved outside this block, or if this is fine as-is.

[tboerger]

Adding an option to opt-out is fine, I know some people that really asked for that.

[robertstettner]

Friendly bump 😄

[robertstettner]

@bradrydzewski Could you please merge this one?