[Backport 2.x] Add workflow for changelog

.github/workflows/changelog_verifier.yml

@@ -0,0 +1,23 @@
+name: "Changelog Verifier"
+on:
+  push:
+    branches-ignore:
+      - 'whitesource-remediate/**'
+      - 'backport/**'
+  pull_request:
+    types: [opened, edited, review_requested, 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/flow-framework'
+    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
+        with:
+          skipLabels: "autocut, skip-changelog"

CHANGELOG.md

@@ -0,0 +1,22 @@
+CHANGELOG
+
+
+Inspired from [Keep a Changelog](https://keepachangelog.com/en/1.1.0/)
+
+2.12.0 Initial Release
+## [Unreleased]
+### Added
+- Github workflow for changelog verification ([#440](https://github.com/opensearch-project/flow-framework/pull/440))
+
+### Changed
+
+### Deprecated
+
+### Removed
+
+### Fixed
+
+### Security
+
+
+[Unreleased]: https://github.com/opensearch-project/flow-framework/compare/2.x...HEAD

CONTRIBUTING.md

@@ -5,6 +5,7 @@
     - [Feature Requests](#feature-requests)
     - [Contributing Code](#contributing-code)
   - [Developer Certificate of Origin](#developer-certificate-of-origin)
+  - [Changelog](#changelog)
   - [Code Coverage](#code-coverage)
   - [Review Process](#review-process)
 
@@ -78,6 +79,23 @@ Signed-off-by: Jane Smith <[email protected]>
 ```
 You may type this line on your own when writing your commit messages. However, if your user.name and user.email are set in your git configs, you can use `-s` or `--signoff` to add the `Signed-off-by` line to the end of the commit message.
 
+## Changelog
+
+Flow Framework maintains version specific changelog by enforcing a change to the ongoing [CHANGELOG](CHANGELOG.md) file adhering to the [Keep A Changelog](https://keepachangelog.com/en/1.1.0/) format.
+
+Briefly, the changes are curated by version, with the changes to the main branch added chronologically to `Unreleased` version. Further, each version has corresponding sections which list out the category of the change - `Added`, `Changed`, `Deprecated`, `Removed`, `Fixed`, `Security`.
+
+### How to add my changes to [CHANGELOG](CHANGELOG.md)?
+
+As a contributor, you must ensure that every pull request has the changes listed out within the corresponding version and appropriate section of [CHANGELOG](CHANGELOG.md) file.
+
+Adding in the change is two step process -
+1. Add your changes to the corresponding section within the CHANGELOG file with dummy pull request information, publish the PR
+
+`Your change here ([#PR_NUMBER](PR_URL))`
+
+2. Update the entry for your change in [`CHANGELOG.md`](CHANGELOG.md) and make sure that you reference the pull request there.
+
 ## Code Coverage
 
 Any new functionality requires testing. Your PR will trigger an automatic assessment of the code coverage of the lines you've added. You should add unit and/or integration tests to exercise as much of your new code as possible.