feat: Allow prepending the generated changelog to an existing one in git-cliff-release (#142)

Author: janbuchar

git-cliff-release/README.md

@@ -7,6 +7,8 @@ This action uses conventional commit history to determine the recommended versio
 - **release_type**: One of `auto` (default), `patch`, `minor`, `major` and `custom`. `auto` means that the version will be determined based on the commit history, `custom` will use the value of the `custom_version` input parameter, and `patch`, `minor` and `major` allow forcing the bump type.
 - **custom_version**: Optional unless the `release_type` is set to `custom`.
 - **cliff_config_path**: Path to a configuration file for git-cliff. If none is given, a built-in configuration will be used.
+- **existing_changelog_path**: Path to an existing changelog. If given, the new changelog contents will be prepended to it intelligently.
+- **token**: Github token to be used by github CLI (should be relevant for private repositories only)
 
 ## Outputs
 

git-cliff-release/action.yaml

@@ -23,6 +23,16 @@ inputs:
     required: false
     type: string
     default: cliff.toml
+  existing_changelog_path:
+    description: Path to an existing changelog. If given, the new changelog contents will be prepended to it intelligently.
+    required: false
+    type: string
+    default: ""
+  token:
+    description: Github token to be used by github CLI
+    required: false
+    type: string
+    default: ${{ github.token }}
 outputs:
   is_prerelease:
     description: For convenience - was the action triggered with release_type = "prerelease"?
@@ -65,8 +75,9 @@ runs:
         GIT_CLIFF_REPOSITORY: ${{ github.workspace }}/__release_metadata_repo
         GIT_CLIFF_WORKDIR: ${{ github.action_path }}
         GITHUB_REPO: ${{ github.repository }}
-        GH_TOKEN: ${{ github.token }}
+        GITHUB_TOKEN: ${{ inputs.token }}
       run: |
+        set -x
         if [[ '${{ inputs.release_type }}' = custom ]]; then
           version_number=$(echo ${{ inputs.custom_version }} | sed s/^v//)
         elif [[ '${{ inputs.release_type }}' = auto || '${{ inputs.release_type }}' = prerelease ]]; then
@@ -85,9 +96,10 @@ runs:
         GIT_CLIFF_REPOSITORY: ${{ github.workspace }}/__release_metadata_repo
         GIT_CLIFF_WORKDIR: ${{ github.action_path }}
         GITHUB_REPO: ${{ github.repository }}
-        GH_TOKEN: ${{ github.token }}
+        GITHUB_TOKEN: ${{ inputs.token }}
       working-directory: ${{ github.action_path }}
       run: |
+        set -x
         echo 'release_notes<<EOF' >> $GITHUB_OUTPUT
         git-cliff --tag "${{ steps.version_number.outputs.tag_name }}" --unreleased --context | 
           python enhance_context.py --repo $GITHUB_REPO --release-notes | 
@@ -102,22 +114,42 @@ runs:
         GIT_CLIFF_REPOSITORY: ${{ github.workspace }}/__release_metadata_repo
         GIT_CLIFF_WORKDIR: ${{ github.action_path }}
         GITHUB_REPO: ${{ github.repository }}
-        GH_TOKEN: ${{ github.token }}
+        GITHUB_TOKEN: ${{ inputs.token }}
       working-directory: ${{ github.action_path }}
       run: |
+        set -x
+        dump_context_args=()
+        enhance_context_args=()
+        print_changelog_args=()
+
+        out_file=$GIT_CLIFF_WORKDIR/new_changelog.md
+
+        if [[ -n "${{ inputs.existing_changelog_path }}" ]]; then
+          out_file=$GIT_CLIFF_WORKDIR/existing_changelog.md
+          cp "${{ github.workspace }}/${{ inputs.existing_changelog_path }}" $out_file
+          sed '/<!-- git-cliff-unreleased-start -->/,/<!-- git-cliff-unreleased-end -->/d' -i $out_file
+
+          dump_context_args+=(--unreleased)
+          print_changelog_args+=(--prepend "$out_file" --unreleased)
+        else
+          print_changelog_args+=(--output "$out_file")
+        fi
+
         if [[ ${{ inputs.release_type }} = prerelease ]]; then
-          echo 'changelog<<EOF' >> $GITHUB_OUTPUT
-          git-cliff --context | 
-            python enhance_context.py --repo $GITHUB_REPO --unreleased-version "${{ steps.version_number.outputs.tag_name }}" | 
-            git-cliff --from-context - >> $GITHUB_OUTPUT
-          echo 'EOF' >> $GITHUB_OUTPUT
+          enhance_context_args+=(--unreleased-version "${{ steps.version_number.outputs.tag_name }}")
         else
-          echo 'changelog<<EOF' >> $GITHUB_OUTPUT
-          git-cliff --tag "${{ steps.version_number.outputs.tag_name }}" --context | 
-            python enhance_context.py --repo $GITHUB_REPO | 
-            git-cliff --from-context - >> $GITHUB_OUTPUT
-          echo 'EOF' >> $GITHUB_OUTPUT
+          dump_context_args+=(--tag "${{ steps.version_number.outputs.tag_name }}")
         fi
+
+        git-cliff --context "${dump_context_args[@]}" |
+          python enhance_context.py --repo $GITHUB_REPO "${enhance_context_args[@]}" |
+          git-cliff --from-context - "${print_changelog_args[@]}"
+
+        sed -i '$a\' $out_file # Make sure there is a newline at the end of the output file
+
+        echo 'changelog<<EOF' >> $GITHUB_OUTPUT
+        cat $out_file >> $GITHUB_OUTPUT
+        echo 'EOF' >> $GITHUB_OUTPUT
     - name: Clean up
       shell: bash
       env:

git-cliff-release/cliff.toml

@@ -14,6 +14,8 @@ All notable changes to this project will be documented in this file.\n
 # template for the changelog body
 # https://keats.github.io/tera/docs/#introduction
 body = """
+{% if not version %}<!-- git-cliff-unreleased-start -->
+{% endif %}\
 {% if version and extra.release_link %}\
     ## [{{ version | trim_start_matches(pat="v") }}]({{ extra.release_link }}) ({{ timestamp | date(format="%Y-%m-%d") }})
 {% elif extra.unreleased_version %}\
@@ -33,7 +35,7 @@ body = """
             {% else %}\
             {{ commit.message | upper_first }}\
             {% endif %}\
-            {{" "}}([{{ commit.id | truncate(length = 7, end = "") }}]({{ commit.extra.commit_link }}))\
+            {% if commit.extra.commit_link %} ([{{ commit.id | truncate(length = 7, end = "") }}]({{ commit.extra.commit_link }})){% endif %}\
             {% if commit.remote.username and extra.is_release_notes %}\
             {{" "}}by @{{ commit.remote.username }}\
             {% elif commit.remote.username %}\
@@ -44,6 +46,8 @@ body = """
             {%- endif %}\
     {% endfor %}
 {% endfor %}\n
+{% if not version %}<!-- git-cliff-unreleased-end -->
+{% endif %}\
 """
 # template for the changelog footer
 footer = """

git-cliff-release/enhance_context.py

@@ -23,6 +23,9 @@ def load_pr_issues(owner: str, repo: str) -> dict[int, list[int]]:
         print(f"fetch_pr_issues.sh output: {output}")
         raise
 
+    if pr_issues is None:
+        return {}
+
     return {int(key): value for key, value in pr_issues.items()}
 
 
@@ -41,7 +44,7 @@ def enhance_release(
 
 
 def enhance_commit(commit: dict[str, Any], pr_issues: dict[int, list[int]]) -> None:
-    pr_number = commit["remote"]["pr_number"]
+    pr_number = commit.get("remote", {}).get("pr_number")
 
     commit["extra"] = commit["extra"] or {}
     commit["extra"]["commit_link"] = f"{repo_url}/commit/{commit['id']}"