Changelog Automation for Squash and Merge commit messages

.github/workflows/update_changelog.yml

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+name: Update Changelog with new commit
+
+permissions:
+  pull-requests: write
+  contents: write
+
+on:
+  pull_request:
+    # Inputs the workflow accepts.
+    types: [closed]
+
+jobs:
+  pull-commit-message:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    outputs:
+      message: ${{ steps.pull.outputs.message }}
+    steps:
+      - uses: actions/checkout@v4
+        continue-on-error: true
+      - name: get merge commit message 
+        id: pull
+        run: |
+         pull_number="$(jq --raw-output .pull_request.number "$GITHUB_EVENT_PATH")" 
+         commit_message="$(git log --pretty="format:%b")"
+         echo message="$commit_message [GH-$pull_number]"  >> $GITHUB_OUTPUT
+  # check-for-changelog-entry
+  changelog-entry:
+    # if contains to check for bug, enhancement, feature
+    if: ${{ contains(needs.pull-commit-message.outputs.message, '[BUG]') || contains(needs.pull-commit-message.outputs.message, '[ENHANCEMENT]') || contains(needs.pull-commit-message.outputs.message, '[FEATURE]') }}
+    runs-on: ubuntu-latest
+    needs: pull-commit-message
+    outputs:
+      optIn: ${{ steps.in.outputs.bool }}
+      entry: ${{  needs.pull-commit-message.outputs.message  }}
+    steps:
+      - name: changelog entry opt in
+        id: in
+        continue-on-error: true
+        run: echo "opted in to changelog entry" | echo bool="true" >> $GITHUB_OUTPUT
+  # if there is a changelog entry, check for PR Open
+  update-changelog:
+    if: needs.changelog-entry.outputs.optIn
+    runs-on: ubuntu-latest
+    needs: changelog-entry
+    steps:
+      - name: Check if PR exists
+        id: check
+        continue-on-error: true
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          prs=$(gh pr list \
+              --repo "$GITHUB_REPOSITORY" \
+              --json title \
+              --label "changelog" \
+              --jq 'length')
+          if [[  $prs -gt 0  ]]; then
+              echo "existing=true" >> "$GITHUB_OUTPUT"
+          fi
+      - uses: actions/checkout@v4
+      - name: check for branch
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        continue-on-error: true
+        run: |
+          BRANCH=automated-changelog
+          if gh api repos/hashicorp/terraform-provider-azurerm/branches/$BRANCH > /dev/null 2>&1; then
+            echo "Branch exists on remote..."
+            git fetch origin $BRANCH
+            git checkout $BRANCH
+          else
+            echo "Branch does not exist on remote, creating locally..."
+            git checkout -b $BRANCH
+          fi
+
+      - name: Create pull request
+      #if changelog PR isn't already open, open one
+      #create a new PR, start with appending the release number and (unreleased)
+        if: '!steps.check.outputs.existing'
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        continue-on-error: true
+        run: |
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git config user.name "github-actions[bot]"
+
+          #new pull request for new release needs the headers all added to the top
+          FILE="CHANGELOG.md"
+          version=$(head -n 1 "$FILE")
+          IFS='.' read major minor patch <<< "$version"
+          ((minor++))
+          patch=$(echo $patch | sed 's/ (.*)//')
+          new_version="${major}.$minor.${patch} (Unreleased)"
+          headers="${new_version}\n\nENHANCEMENTS:\n\nFEATURES:\n\nBUG FIXES:\n"
+          temp_file=$(mktemp)
+          echo -e "$headers" > "$temp_file"
+          cat "$FILE" >> "$temp_file"
+          mv "$temp_file" "$FILE"
+          echo "File has been updated."
+
+          major=$(echo $major | sed 's/## //')
+          RELEASENUM="${major}.$minor.${patch}"
+
+          git add CHANGELOG.md
+          git commit -m "staring new changelog PR"
+          git push --set-upstream origin automated-changelog
+          echo "Creating a new pull request"
+          gh pr create \
+          --repo "$GITHUB_REPOSITORY" \
+          --base main \
+          --head automated-changelog \
+          -l "changelog" \
+          -t "CHANGELOG.md for $RELEASENUM" \
+          -b "Automated changelog for next release, $RELEASENUM"
+
+      - name: Set up Go
+        uses: actions/setup-go@v3  # Set up go
+        with:
+          go-version: '1.20'
+
+      - name: Add commit message to changelog pull request
+      # at this point a PR is opened for sure, now add entry
+        env:
+            GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        continue-on-error: true
+        run: |
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git config user.name "github-actions[bot]"
+
+          go run scripts/update_changelog.go CHANGELOG.md '${{ needs.changelog-entry.outputs.entry }}'
+
+          git add CHANGELOG.md
+          git commit -m "Update changelog"
+          git push --set-upstream origin automated-changelog
+

scripts/update_changelog.go

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+package main
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"strings"
+)
+
+// Function to find the header and return its index
+func findHeaderIndex(lines []string, header string) int {
+	for i, line := range lines {
+		if strings.HasPrefix(line, header) {
+			return i
+		}
+	}
+	return -1
+}
+
+// Function to append the new entry under the appropriate header in alphabetical order
+func appendUnderHeader(filePath string, newEntry, header string) error {
+	// Open the file for reading and appending
+	file, err := os.OpenFile(filePath, os.O_RDWR|os.O_CREATE, 0644)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	// Read the file content
+	var lines []string
+	scanner := bufio.NewScanner(file)
+	for scanner.Scan() {
+		lines = append(lines, scanner.Text())
+	}
+
+	if err := scanner.Err(); err != nil {
+		return err
+	}
+
+	// Find the correct header section
+	headerIndex := findHeaderIndex(lines, header)
+
+	// Now append the new entry under the correct header
+	// Check if the next line is empty or not for proper formatting
+	insertIndex := headerIndex + 1
+	for i := headerIndex + 1; i < len(lines); i++ {
+		// Look for the next header to break the section
+		if strings.HasPrefix(lines[i], "[") {
+			insertIndex = i
+			break
+		}
+	}
+
+	// Remove the header prefix from the new entry
+	// Trim the header prefix based on which one it matches
+	var trimmedEntry string
+	if strings.HasPrefix(newEntry, "[BUG]") {
+		trimmedEntry = strings.TrimPrefix(newEntry, "[BUG] ")
+	} else if strings.HasPrefix(newEntry, "[ENHANCEMENT]") {
+		trimmedEntry = strings.TrimPrefix(newEntry, "[ENHANCEMENT] ")
+	} else if strings.HasPrefix(newEntry, "[FEATURE]") {
+		trimmedEntry = strings.TrimPrefix(newEntry, "[FEATURE] ")
+	} else {
+		// If the entry doesn't match one of the expected headers, print an error
+		fmt.Println("Error: New entry must start with one of the headers [BUG], [ENHANCEMENT], or [FEATURE].")
+		return nil
+	}
+
+	// Insert the new entry under the header
+	var section []string
+	for i := headerIndex + 1; i < insertIndex; i++ {
+		section = append(section, lines[i])
+	}
+	section = append(section, trimmedEntry)
+
+	// Rebuild the file content
+	lines = append(lines[:headerIndex+1], append(section, lines[insertIndex:]...)...)
+
+	// Open the file for writing and overwrite the content
+	file, err = os.OpenFile(filePath, os.O_RDWR|os.O_TRUNC, 0644)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+
+	// Write the updated content back to the file
+	writer := bufio.NewWriter(file)
+	for _, line := range lines {
+		_, err := writer.WriteString(line + "\n")
+		if err != nil {
+			return err
+		}
+	}
+	return writer.Flush()
+}
+
+func main() {
+	if len(os.Args) != 3 {
+		fmt.Println("Usage: go run update_changelog.go CHANGELOG.md <new_entry>")
+		return
+	}
+
+	filePath := os.Args[1]
+	newEntry := os.Args[2]
+
+	// Validate and determine the correct header for the new entry
+	var selectedHeader string
+	if strings.HasPrefix(newEntry, "[BUG]") {
+		selectedHeader = "BUG FIXES:"
+	} else if strings.HasPrefix(newEntry, "[ENHANCEMENT]") {
+		selectedHeader = "ENHANCEMENTS:"
+	} else if strings.HasPrefix(newEntry, "[FEATURE]") {
+		selectedHeader = "FEATURES:"
+	} else {
+		// If the entry doesn't match one of the expected headers, print an error
+		fmt.Println("Error: New entry must start with one of the headers [BUG], [ENHANCEMENT], or [FEATURE].")
+		return
+	}
+
+	// Call the function to append under the appropriate header
+	err := appendUnderHeader(filePath, newEntry, selectedHeader)
+	if err != nil {
+		fmt.Println("Error appending to file:", err)
+		return
+	}
+
+	fmt.Println("Successfully appended the new entry under the", selectedHeader, "header.")
+}