Automate per-package release for specific components (#2875)

scripts/generate_release_notes.sh

@@ -0,0 +1,26 @@
+#!/bin/bash
+
+# This script copies release notes for the current version from CHANGELOG.md file
+# and stores them in /tmp/release-notes.txt.
+# It also stores them in a /tmp/CHANGELOG_SECTION.md which is used later to copy them over to the
+# CHANGELOG in main branch which is done by merge_changelog_to_main script.
+
+# This script is called from the release workflows (package-release.yml and release.yml).
+
+set -ev
+
+# conditional block not indented because of the heredoc
+if [[ ! -z $PRIOR_VERSION_WHEN_PATCH ]]; then
+cat > /tmp/release-notes.txt << EOF
+This is a patch release on the previous $PRIOR_VERSION_WHEN_PATCH release, fixing the issue(s) below.
+
+EOF
+fi
+
+# CHANGELOG_SECTION.md is also used at the end of the release workflow
+# for copying the change log updates to main
+sed -n "0,/^## Version ${VERSION}/d;/^## Version /q;p" $CHANGELOG > /tmp/CHANGELOG_SECTION.md
+
+# the complex perl regex is needed because markdown docs render newlines as soft wraps
+# while release notes render them as line breaks
+perl -0pe 's/(?<!\n)\n *(?!\n)(?![-*] )(?![1-9]+\. )/ /g' /tmp/CHANGELOG_SECTION.md >> /tmp/release-notes.txt