Feat: Allow repo specific dangerfile.

danger/README.md

@@ -30,6 +30,16 @@ jobs:
   * required: false
   * default: `${{ github.token }}`
 
+* `extra-dangerfile`: Path to an additional dangerfile to run custom checks.
+  * type: string
+  * required: false
+  * default: ""
+
+* `extra-install-packages`: Additional packages that are required by the extra-dangerfile, you can find a list of packages here: https://packages.debian.org/search?suite=bookworm&keywords=curl.
+  * type: string
+  required: false
+  default: ""
+
 ## Outputs
 
 * `outcome`: Whether the Danger run finished successfully. Possible values are `success`, `failure`, `cancelled`, or `skipped`.
@@ -52,4 +62,18 @@ The Danger action runs the following checks:
 - **Conventional commits**: Validates commit message format and PR title conventions
 - **Cross-repo links**: Checks for proper formatting of links in changelog entries
 
-For detailed rule implementations, see [dangerfile.js](dangerfile.js).
+For detailed rule implementations, see [dangerfile.js](dangerfile.js).
+
+## Extra Danger File
+
+When using an extra dangerfile, the file must be inside the repository and written in CommonJS syntax. You can use the following snippet to export your dangerfile:
+
+```JavaScript
+module.exports = async function ({ fail, warn, message, markdown, danger }) {
+  ...
+  const gitUrl = danger.github.pr.head.repo.git_url;
+  ...
+  warn('...');
+}
+
+```

danger/action.yml

@@ -7,6 +7,14 @@ inputs:
     description: 'Token for the repo. Can be passed in using {{ secrets.GITHUB_TOKEN }}'
     required: false
     default: ${{ github.token }}
+  extra-dangerfile:
+    description: 'Path to additional dangerfile to run after the main checks'
+    type: string
+    required: false
+  extra-install-packages:
+    description: 'Additional apt packages to install in the DangerJS container (space-separated package names)'
+    type: string
+    required: false
 
 outputs:
   outcome:
@@ -28,12 +36,25 @@ runs:
       shell: pwsh
       run: Get-Content '${{ github.action_path }}/danger.properties' | Tee-Object $env:GITHUB_OUTPUT -Append
 
+    # Validate extra-install-packages to prevent code injection
+    - name: Validate package names
+      if: ${{ inputs.extra-install-packages }}
+      shell: bash
+      run: |
+        packages="${{ inputs.extra-install-packages }}"
+        # Only allow alphanumeric characters, hyphens, periods, plus signs, underscores, and spaces
+        if ! echo "$packages" | grep -E '^[a-zA-Z0-9._+-]+( [a-zA-Z0-9._+-]+)*$' > /dev/null; then
+          echo "::error::Invalid package names in extra-install-packages. Only alphanumeric characters, hyphens, periods, plus signs, underscores, and spaces are allowed."
+          exit 1
+        fi
+
     # Using a pre-built docker image in GitHub container registry instead of NPM to reduce possible attack vectors.
-    - name: Run DangerJS
-      id: danger
+    - name: Setup container
       shell: bash
       run: |
-        docker run \
+        # Start a detached container with all necessary volumes and environment variables
+        docker run -td --name danger \
+          --entrypoint /bin/bash \
           --volume ${{ github.workspace }}:/github/workspace \
           --volume ${{ github.action_path }}:${{ github.action_path }} \
           --volume ${{ github.event_path }}:${{ github.event_path }} \
@@ -42,5 +63,21 @@ runs:
           -e "INPUT_ARGS" -e "GITHUB_JOB" -e "GITHUB_REF" -e "GITHUB_SHA" -e "GITHUB_REPOSITORY" -e "GITHUB_REPOSITORY_OWNER" -e "GITHUB_RUN_ID" -e "GITHUB_RUN_NUMBER" -e "GITHUB_RETENTION_DAYS" -e "GITHUB_RUN_ATTEMPT" -e "GITHUB_ACTOR" -e "GITHUB_TRIGGERING_ACTOR" -e "GITHUB_WORKFLOW" -e "GITHUB_HEAD_REF" -e "GITHUB_BASE_REF" -e "GITHUB_EVENT_NAME" -e "GITHUB_SERVER_URL" -e "GITHUB_API_URL" -e "GITHUB_GRAPHQL_URL" -e "GITHUB_REF_NAME" -e "GITHUB_REF_PROTECTED" -e "GITHUB_REF_TYPE" -e "GITHUB_WORKSPACE" -e "GITHUB_ACTION" -e "GITHUB_EVENT_PATH" -e "GITHUB_ACTION_REPOSITORY" -e "GITHUB_ACTION_REF" -e "GITHUB_PATH" -e "GITHUB_ENV" -e "GITHUB_STEP_SUMMARY" -e "RUNNER_OS" -e "RUNNER_ARCH" -e "RUNNER_NAME" -e "RUNNER_TOOL_CACHE" -e "RUNNER_TEMP" -e "RUNNER_WORKSPACE" -e "ACTIONS_RUNTIME_URL" -e "ACTIONS_RUNTIME_TOKEN" -e "ACTIONS_CACHE_URL" -e GITHUB_ACTIONS=true -e CI=true \
           -e GITHUB_TOKEN="${{ inputs.api-token }}" \
           -e DANGER_DISABLE_TRANSPILATION="true" \
+          -e EXTRA_DANGERFILE_INPUT="${{ inputs.extra-dangerfile }}" \
           ghcr.io/danger/danger-js:${{ steps.config.outputs.version }} \
-          --failOnErrors --dangerfile ${{ github.action_path }}/dangerfile.js
+          -c "sleep infinity"
+
+    - name: Setup additional packages
+      if: ${{ inputs.extra-install-packages }}
+      shell: bash
+      run: |
+        docker exec --user root danger apt-get update
+        echo "Installing packages: ${{ inputs.extra-install-packages }}"
+        docker exec --user root danger sh -c "set -e && apt-get install -y --no-install-recommends ${{ inputs.extra-install-packages }}"
+        echo "All additional packages installed successfully."
+
+    - name: Run DangerJS
+      id: danger
+      shell: bash
+      run: |
+        docker exec --user $(id -u) danger danger ci --fail-on-errors --dangerfile ${{ github.action_path }}/dangerfile.js

danger/dangerfile.js

@@ -186,10 +186,49 @@ async function checkActionsArePinned() {
   }
 }
 
+async function CheckFromExternalChecks() {
+  // Get the external dangerfile path from environment variable (passed via workflow input)
+  // Priority: EXTRA_DANGERFILE (absolute path) -> EXTRA_DANGERFILE_INPUT (relative path)
+  const extraDangerFilePath = process.env.EXTRA_DANGERFILE || process.env.EXTRA_DANGERFILE_INPUT;
+  console.log(`::debug:: Checking from external checks: ${extraDangerFilePath}`);
+  if (extraDangerFilePath) {
+    try {
+      const workspaceDir = '/github/workspace';
+      const path = require('path');
+      const customPath = path.join('/github/workspace', extraDangerFilePath);
+
+      if (!customPath.startsWith(workspaceDir)) {
+        fail(`Invalid dangerfile path: ${customPath}. Path traversal is not allowed.`);
+        return;
+      }      
+
+      const extraModule = require(customPath);
+      if (typeof extraModule !== 'function') { 
+        warn(`EXTRA_DANGERFILE must export a function at ${customPath}`); 
+        return; 
+      }
+      await extraModule({
+        fail: fail, 
+        warn: warn,
+        message: message, 
+        markdown: markdown,
+        danger: danger,
+      });
+    } catch (err) {
+      if (err.message && err.message.includes('Cannot use import statement outside a module')) {
+        warn(`External dangerfile uses ES6 imports. Please convert to CommonJS syntax (require/module.exports) or use .mjs extension with proper module configuration.\nFile: ${customPath}`);
+      } else {
+        warn(`Could not load custom Dangerfile: ${extraDangerFilePath}\n${err}`);
+      }
+    }
+  }
+}
+
 async function checkAll() {
   await checkDocs();
   await checkChangelog();
   await checkActionsArePinned();
+  await CheckFromExternalChecks();
 }
 
 schedule(checkAll);