Enhance changelog workflow to check for missing labels #520

	name: "Changelog Verifier"
	on:
	pull_request:
	types: [opened, synchronize, reopened, ready_for_review, labeled, unlabeled]

	jobs:
	# Enforces the update of a changelog file on every pull request
	verify-changelog:
	# if: github.repository == 'opensearch-project/OpenSearch'
	runs-on: ubuntu-latest
	steps:
	- uses: actions/checkout@v4
	with:
	token: ${{ secrets.GITHUB_TOKEN }}
	ref: ${{ github.event.pull_request.head.sha }}
	- uses: dangoslen/changelog-enforcer@v3
	id: verify-changelog-3x
	with:
	skipLabels: "autocut, skip-changelog"
	changeLogPath: 'CHANGELOG-3.0.md'
	continue-on-error: true
	- uses: dangoslen/changelog-enforcer@v3
	id: verify-changelog
	with:
	skipLabels: "autocut, skip-changelog"
	changeLogPath: 'CHANGELOG.md'
	continue-on-error: true
	- run: \|
	if [[ ${{ steps.verify-changelog-3x.outcome }} == 'failure' && ${{ steps.verify-changelog.outcome }} == 'failure' ]]; then
	echo "error: Please ensure a changelog entry exists in CHANGELOG.md or CHANGELOG-3.0.md"
	exit 1
	fi

	has_backport_label=false
	labels=${{ github.event.pull_request.labels.*.name }}
	echo "Number of labels: ${#labels[@]}"
	for label in $labels; do
	echo "Label: $label"
	if [[ $label =~ "backport" ]]; then
	has_backport_label=true
	break
	fi
	done

	if [[ ${{ steps.verify-changelog.outcome }} == 'success' && $has_backport_label == false ]]; then
	echo "error: Please make sure that the PR has a backport label associated with it when making an entry to the CHANGELOG.md file"
	exit 1
	fi

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