Switch PR labeling to use GitHub Actions. (#7630)

This decouples the PR labeling process from the main CI process, allowing
them to run completely independenly of each other.

The new labeling configuration is based on copying, extending, and
correcting the existing labeling rules in the `labeler.sh` script which
the commit is removing.

Labeling is configured through `.github/labeler.yml` file. Check there
for info on the exact format.

The exact configuration being used will update labels on PR's whenever
one is opened, updated, reopened, or marked ready for review. It will
not remove existing labels from the PR, only add new ones.

2 files changed, 108 insertions, 0 deletions

diff --git a/.github/labeler.yml b/.github/labeler.yml
new file mode 100644
index 0000000000..86c0c8cd86
--- /dev/null
+++ b/.github/labeler.yml
@@ -0,0 +1,91 @@
+# This configures label matching for PR's.
+#
+# The keys are labels, and the values are lists of minimatch patterns
+# to which those labels apply.
+#
+# NOTE: This can only add labels, not remove them.
+# NOTE: Due to YAML syntax limitations, patterns or labels which start
+# with a character that is part of the standard YAML syntax must be
+# quoted.
+#
+# Please keep the labels sorted and deduplicated.
+
+area/backends:
+  - backends/*
+  - backends/**
+  - exporting/*
+  - exporting/**/*
+
+area/ci:
+  - .travis/*
+  - .travis/**/*
+  - .github/*
+  - .github/**/*
+
+area/collectors:
+  - collectors/*
+  - collectors/**/*
+
+area/daemon:
+  - daemon/*
+  - daemon/**/*
+
+area/database:
+  - database/*
+  - database/**/*
+
+area/docs:
+  - "**/*.md"
+  - diagrams/*
+  - diagrams/**/*
+  - netlify.toml
+
+area/external/python:
+  - collectors/python.d.plugin/*
+  - collectors/python.d.plugin/**/*
+
+area/external:
+  - collectors/charts.d.plugin/*
+  - collectors/charts.d.plugin/**/*
+  - collectors/node.d.plugin/*
+  - collectors/node.d.plugin/**/*
+
+area/health:
+  - health/*
+  - health/**/*
+
+area/packaging:
+  - build/*
+  - build/**/*
+  - contrib/*
+  - contrib/**/*
+  - packaging/*
+  - packaging/**/*
+  - system/*
+  - system/**/*
+  - netdata-installer.sh
+  - CMakeLists.txt
+  - configure.ac
+  - Makefile.am
+  - "**/Makefile.am"
+  - netdata.spec.in
+
+area/registry:
+  - registry/*
+  - registry/**/*
+
+area/streaming:
+  - streaming/*
+  - streaming/**/*
+
+area/tests:
+  - tests/*
+  - tests/**/*
+  - daemon/unit_test*
+  - coverity-scan.sh
+  - cppcheck.sh
+  - netdata.cppcheck
+
+area/web:
+  - web/*
+  - web/**/*
diff --git a/.github/workflows/labeler.yml b/.github/workflows/labeler.yml
new file mode 100644
index 0000000000..e0d45d991b
--- /dev/null
+++ b/.github/workflows/labeler.yml
@@ -0,0 +1,17 @@
+---
+# Handles labelling of PR's.
+name: Pull Request Labeler
+on:
+  pull_request:
+    types:
+      - opened
+      - synchronized
+      - reopened
+      - ready_for_review
+jobs:
+  labeler:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/labeler@v2
+        with:
+          repo-token: "${{ secrets.GITHUB_TOKEN }}"