ci: add workflow that comments changelog preview on PRs

.github/scripts/preview-changelog.sh

@@ -0,0 +1,16 @@
+#! /bin/bash
+
+set -euo pipefail
+
+if [ $# -eq 0 ]; then
+    echo "No arguments supplied. Use with '--token=<github token> --target-branch=<branch>'"
+    exit 1
+fi
+
+dry_run_output=$(npm run --silent release-please-dry-run -- "$@")
+
+echo "$dry_run_output" | grep --silent "Would open 1 pull request" || exit 0
+
+extract_everything_between_tripledashes="/---/,/---/p"
+drop_first_and_last_line='1d;$d'
+echo "$dry_run_output" | sed -n "$extract_everything_between_tripledashes" | sed "$drop_first_and_last_line"

.github/workflows/changelog-preview.yml

@@ -0,0 +1,51 @@
+name: Changelog Preview
+
+on:
+  pull_request:
+
+jobs:
+  previewChangelog:
+    name: Preview Changelog
+    runs-on: ubuntu-latest
+    if: ${{ !github.event.pull_request.draft }}
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: actions/setup-node@v4
+        with:
+          node-version: lts/*
+
+      - uses: actions/cache@v4
+        with:
+          path: ~/.npm
+          key: ${{ runner.os }}-node-${{ hashFiles('package-lock.json') }}
+
+      - name: Install npm packages
+        run: npm ci
+
+      - name: Generate Changelog Preview
+        id: changelog-preview
+        run: |
+          changelog=$(npm run --silent release-please-changelog-preview -- --token=${{ secrets.GITHUB_TOKEN }} --target-branch=${{ github.head_ref || github.ref_name }})
+
+          echo "changelog<<EOF
+          $changelog
+          EOF" >> "$GITHUB_OUTPUT"
+
+      - name: Comment on PR
+        uses: marocchino/sticky-pull-request-comment@v2
+        if: ${{ steps.changelog-preview.outputs.changelog != '' }}
+        with:
+          skip_unchanged: true
+          header: changelogPreview
+          message: |
+            This is a preview of the changelog of the next release:
+
+            ${{ steps.changelog-preview.outputs.changelog }}
+
+      - name: Delete PR Comment
+        uses: marocchino/sticky-pull-request-comment@v2
+        if: ${{ steps.changelog-preview.outputs.changelog == '' }}
+        with:
+          header: changelogPreview
+          delete: true

package.json

@@ -13,6 +13,7 @@
   "scripts": {
     "commitlint:last-commit": "commitlint --from=HEAD~1 --verbose",
     "commitlint:merge-base": "commitlint --from=$(git merge-base HEAD main) --verbose",
-    "release-please-dry-run": "npx release-please release-pr --dry-run --config-file=release-please-config.json --manifest-file=.release-please-manifest.json --repo-url='https://github.com/GenSpectrum/LAPIS-SILO'"
+    "release-please-dry-run": "npx release-please release-pr --dry-run --config-file=release-please-config.json --manifest-file=.release-please-manifest.json --repo-url='https://github.com/GenSpectrum/LAPIS-SILO'",
+    "release-please-changelog-preview": ".github/scripts/preview-changelog.sh"
   }
 }