feat: support labels copier (#207)

* feat: support labels copier * docs * rename * Update mergify/labels-copier/README.md * fix and add verbose * docs * fix * improve * fix * the opposite * add exclude * refactor * remove additional input for now * docs * simplify: gh pr edit allows passing multiple labels * outputs * unrequired
elastic · Jan 9, 2025 · a2467bf · a2467bf
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diff --git a/.github/workflows/test-mergify-labels-copier.yml b/.github/workflows/test-mergify-labels-copier.yml
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+name: test-mergify-labels-copier
+
+on:
+  merge_group: ~
+  workflow_dispatch:
+  push:
+    paths:
+      - '.github/workflows/test-mergify-labels-copier.yml'
+      - 'mergify/labels-copier/**'
+
+permissions:
+  contents: read
+
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Get token
+        id: get_token
+        uses: tibdex/github-app-token@3beb63f4bd073e61482598c45c71c1019b59b73a # v2.1.0
+        with:
+          app_id: ${{ secrets.OBS_AUTOMATION_APP_ID }}
+          private_key: ${{ secrets.OBS_AUTOMATION_APP_PEM }}
+          permissions: >-
+            {
+              "pull_requests": "read"
+            }
+      - uses: ./mergify/labels-copier
+        id: validation
+        with:
+          github-token: ${{ steps.get_token.outputs.token }}
+          repository: "elastic/apm-server"
+          pull-request: "15035"
+          excluded-labels-regex: "^backport-*"
+        env:
+          DRY_RUN: true
+
+      - name: assert labels are not empty
+        run: test -n "${{ steps.validation.outputs.labels }}"
diff --git a/mergify/labels-copier/README.md b/mergify/labels-copier/README.md
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+# <!--name-->github/labels-copier<!--/name-->
+
+[![usages](https://img.shields.io/badge/usages-white?logo=githubactions&logoColor=blue)](https://github.com/search?q=elastic%2Foblt-actions%2F2Fmergify%labels-copier+%28path%3A.github%2Fworkflows+OR+path%3A**%2Faction.yml+OR+path%3A**%2Faction.yaml%29&type=code)
+[![test-mergify-labels-copier](https://github.com/elastic/oblt-actions/actions/workflows/test-github-comment-reaction.yml/badge.svg?branch=main)](https://github.com/elastic/oblt-actions/actions/workflows/test-mergify-labels-copier.yml)
+
+<!--description-->
+copies pull request labels to backported PRs
+<!--/description-->
+
+## Inputs
+<!--inputs-->
+| Name                    | Description                                     | Required | Default                                   |
+|-------------------------|-------------------------------------------------|----------|-------------------------------------------|
+| `excluded-labels-regex` | labels to be excluded in regex format           | `false`  | ` `                                       |
+| `github-token`          | The GitHub token to use for API requests        | `false`  | `${{ github.token }}`                     |
+| `repository`            | The GitHub repository to use for API requests   | `false`  | `${{ github.repository }}`                |
+| `pull-request`          | The GitHub pull-request to use for API requests | `false`  | `${{ github.event.pull_request.number }}` |
+<!--/inputs-->
+
+## Outputs
+<!--outputs-->
+| Name     | Description             |
+|----------|-------------------------|
+| `labels` | The labels to be copied |
+<!--/outputs-->
+
+## Usage
+
+<!--usage action="elastic/oblt-actions/**" version="env:VERSION"-->
+```yaml
+name: mergify backport labels copier
+
+on:
+  pull_request_target:
+    types:
+      - opened
+jobs:
+  react:
+    runs-on: ubuntu-latest
+    if: startsWith(github.head_ref, 'mergify/bp/')
+    permissions:
+      pull-requests: write
+    steps:
+      - uses: elastic/oblt-actions/mergify/labels-copier@v1
+        with:
+          excluded-labels-regex: "^backport-*"
+      # ...
+```
+<!--/usage-->
diff --git a/mergify/labels-copier/action.yml b/mergify/labels-copier/action.yml
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+name: 'github/labels-copier'
+
+description: 'copies pull request labels to backported PRs'
+
+inputs:
+  excluded-labels-regex:
+    description: 'labels to be excluded in regex format'
+    required: false
+    default: ''
+  github-token:
+    description: 'The GitHub token to use for API requests'
+    required: false
+    default: ${{ github.token }}
+  repository:
+    description: 'The GitHub repository to use for API requests'
+    required: false
+    default: ${{ github.repository }}
+  pull-request:
+    description: 'The GitHub pull-request to use for API requests'
+    required: false
+    default: ${{ github.event.pull_request.number }}
+outputs:
+  labels:
+    description: 'The labels to be copied'
+    value: ${{ steps.copy-labels.outputs.labels }}
+runs:
+  using: "composite"
+  steps:
+    - name: Copying labels
+      id: copy-labels
+      shell: bash
+      env:
+        REPOSITORY_URL: ${{ github.server_url }}/${{ inputs.repository }}
+        PR_URL: ${{ github.server_url }}/${{ inputs.repository }}/pull/${{ inputs.pull-request }}
+        GH_TOKEN: ${{ inputs.github-token}}
+        EXCLUDED_LABEL: ${{ inputs.excluded-labels-regex }}
+      run: ${{ github.action_path }}/copy.sh
diff --git a/mergify/labels-copier/copy.sh b/mergify/labels-copier/copy.sh
@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# Environment variables:
+#  PR_URL
+#  REPOSITORY_URL
+#  EXCLUDED_LABEL
+#  DRY_RUN
+#  RUNNER_DEBUG
+#
+# You can run this locally for testing purposes:
+#
+# $ REPOSITORY_URL=https://github.com/elastic/apm-server PR_URL=https://github.com/elastic/apm-server/pull/15035 EXCLUDED_LABEL=backport-* DRY_RUN=true sh mergify/labels-copier/copy.sh
+#
+
+set -eo pipefail
+
+# Support debugging in GitHub actions when RUNNER_DEBUG is set.
+if [ -n "$RUNNER_DEBUG" ] ; then
+  set -x
+fi
+
+# Get the PR Number from the body since Mergify uses the PR number as the body.
+pr_number=$(gh pr view --json body -q ".body" "$PR_URL" | sed -n -e '/automatic backport of pull request/,/done/p' | cut -d"#" -f2 | cut -d" " -f1)
+
+# Get the labels from the PR and filter out the excluded labels.
+labels=$(gh pr view --json labels "${REPOSITORY_URL}/pull/$pr_number" | jq -r --arg regex "$EXCLUDED_LABEL" '.labels | map(select(.name | test($regex) | not)) | map(.name) | join(",")')
+if [ -n "$CI" ] ; then
+  echo "labels=$labels" >> "$GITHUB_OUTPUT"
+fi
+echo ">> $labels will be added"
+if [ "$DRY_RUN" == "true" ]; then
+  echo ">> DRY_RUN is set, skipping the label addition"
+else
+  gh pr edit --add-label "$labels" "$PR_URL"
+fi