add CHANGELOG.md (#465)

*Issue #, if available:*

*Description of changes:*
Add CHANGELOG.md to track future features and fixes made to ADOT.

Updated pr-build.yml workflow to check that CHANGELOG.md has been
updated for all changes that affect SDK behavior.

Updated pre-release-prepare.yml workflow to update CHANGELOG in both
release series branch and main branch, moving the Unreleased changes
under a header for the new release version.

By submitting this pull request, I confirm that you can use, modify,
copy, and redistribute this contribution, under the terms of your
choice.

---------

Co-authored-by: Thomas Pierce <[email protected]>

Author: ezhang6811

.github/workflows/post-release-version-bump.yml

@@ -6,6 +6,10 @@ on:
       version:
         description: 'Version number (e.g., 1.0.1)'
         required: true
+      is_patch:
+        description: 'Is this a patch? (true or false)'
+        required: true
+        default: 'false'
 
 env:
   AWS_DEFAULT_REGION: us-east-1
@@ -100,8 +104,22 @@ jobs:
           sed -i 's/__version__ = ".*"/__version__ = "'$DEV_VERSION'"/' aws-opentelemetry-distro/src/amazon/opentelemetry/distro/version.py
           VERSION="${{ github.event.inputs.version }}"
           sed -i 's/python:v.*"/python:v'$VERSION'"/' .github/workflows/daily-scan.yml
+          
+          # for patch releases, avoid merge conflict by manually resolving CHANGELOG with main
+          if [[ "${{ github.event.inputs.is_patch }}" == "true" ]]; then
+            # Copy the patch release entries
+            sed -n "/^## v${VERSION}/,/^## v[0-9]/p" CHANGELOG.md | sed '$d' > /tmp/patch_release_section.txt
+
+            git fetch origin main
+            git show origin/main:CHANGELOG.md > CHANGELOG.md
+
+            # Insert the patch release entries after Unreleased
+            awk -i inplace '/^## v[0-9]/ && !inserted { system("cat /tmp/patch_release_section.txt"); inserted=1 } {print}' CHANGELOG.md
+          fi
+          
           git add aws-opentelemetry-distro/src/amazon/opentelemetry/distro/version.py
           git add .github/workflows/daily-scan.yml
+          git add CHANGELOG.md
           git commit -m "Prepare main for next development cycle: Update version to $DEV_VERSION"
           git push --set-upstream origin "prepare-main-for-next-dev-cycle-${VERSION}"
 
@@ -118,3 +136,13 @@ jobs:
           By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice." \
                        --head prepare-main-for-next-dev-cycle-${VERSION} \
                        --base main
+
+      - name: Force our CHANGELOG to override merge conflicts
+        run: |
+          git merge origin/main || true
+          git checkout --ours CHANGELOG.md
+          git add CHANGELOG.md
+          if ! git diff --quiet --cached; then
+            git commit -m "Force our CHANGELOG to override merge conflicts"
+            git push origin "post-release-${VERSION}"
+          fi

.github/workflows/pr-build.yml

@@ -10,6 +10,42 @@ permissions:
   contents: read
 
 jobs:
+  changelog-check:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+          
+      - name: Check CHANGELOG
+        run: |
+          # Check if PR is from workflows bot or dependabot
+          if [[ "${{ github.event.pull_request.user.login }}" == "aws-application-signals-bot" ]]; then
+            echo "Skipping check: PR from aws-application-signals-bot"
+            exit 0
+          fi
+          
+          if [[ "${{ github.event.pull_request.user.login }}" == "dependabot[bot]" ]]; then
+            echo "Skipping check: PR from dependabot"
+            exit 0
+          fi
+          
+          # Check for skip changelog label
+          if echo '${{ toJSON(github.event.pull_request.labels.*.name) }}' | jq -r '.[]' | grep -q "skip changelog"; then
+            echo "Skipping check: skip changelog label found"
+            exit 0
+          fi
+          
+          # Fetch base branch and check for CHANGELOG modifications
+          git fetch origin ${{ github.base_ref }}
+          if git diff --name-only origin/${{ github.base_ref }}..HEAD | grep -q "CHANGELOG.md"; then
+            echo "CHANGELOG.md entry found - check passed"
+            exit 0
+          fi
+          
+          echo "It looks like you didn't add an entry to CHANGELOG.md. If this change affects the SDK behavior, please update CHANGELOG.md and link this PR in your entry. If this PR does not need a CHANGELOG entry, you can add the 'Skip Changelog' label to this PR."
+          exit 1
+
   build:
     runs-on: ubuntu-latest
     strategy:

.github/workflows/pre-release-prepare.yml

@@ -94,6 +94,13 @@ jobs:
           git commit -am "Update version to ${VERSION}"
           git push origin "v${VERSION}_release"
 
+      - name: Update CHANGELOG for release
+        run: |
+          sed -i "s/## Unreleased/## Unreleased\n\n## v${VERSION} - $(date +%Y-%m-%d)/" CHANGELOG.md
+          git add CHANGELOG.md
+          git commit -m "Update CHANGELOG for version ${VERSION}"
+          git push origin "v${VERSION}_release"
+
       - name: Create pull request against the release branch
         env:
           GITHUB_TOKEN: ${{ env.BOT_TOKEN_GITHUB_RW_PATOKEN }}

CHANGELOG.md

@@ -0,0 +1,13 @@
+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+> **Note:** This CHANGELOG was created starting from version 0.12.0. Earlier changes are not documented here.
+
+For any change that affects end users of this package, please add an entry under the **Unreleased** section. Briefly summarize the change and provide the link to the PR. Example:
+- add GenAI attribute support for Amazon Bedrock models
+  ([#300](https://github.com/aws-observability/aws-otel-python-instrumentation/pull/300))
+
+If your change does not need a CHANGELOG entry, add the "skip changelog" label to your PR.
+
+## Unreleased