chore(IDX): replace checkout with changed files action

Author: cgundy

.github/workflows/internal_vs_external.yml

@@ -69,33 +69,28 @@ jobs:
           repository: dfinity/public-workflows
           path: public-workflows
 
-        # Then switch back to this repository to make sure it's run from current
-      - name: Checkout Original Repository
-        uses: actions/checkout@v4
-        with:
-          path: current-repo # need to specify another path to avoid overwriting the first checkout
-          repository: ${{ github.event.pull_request.head.repo.full_name }}
-          ref: ${{ github.head_ref }}
-          fetch-depth: 256
-
       - name: Python Setup
         uses: ./public-workflows/.github/workflows/python-setup
         with:
           working-directory: public-workflows
 
+      - name: Get changed files
+        id: changed-files
+        uses: tj-actions/changed-files@ed68ef82c095e0d48ec87eccea555d944a631a4c # v46.0.5
+        with:
+          use_rest_api: 'true'
+
       - name: Check External Changes
         id:  check-external-changes
         run: |
           export PYTHONPATH="$PWD/public-workflows/reusable_workflows/"
           python public-workflows/reusable_workflows/repo_policies/check_external_changes.py
         shell: bash
         env:
+          CHANGED_FILES: ${{ steps.changed-files.outputs.all_changed_files }}
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }} # no actual token stored, read-only permissions
           ORG: ${{ github.repository_owner }}
           REPO: ${{ github.event.repository.name }}
-          MERGE_BASE_SHA: ${{ github.event.pull_request.base.sha }}
-          BRANCH_HEAD_SHA: ${{ github.event.pull_request.head.sha }}
-          REPO_PATH: current-repo
 
       - name: Add PR Comment
         uses: actions/github-script@v7

reusable_workflows/repo_policies/check_external_changes.py

@@ -63,16 +63,14 @@ def check_files_against_blacklist(changed_files: list, blacklist_files: list) ->
 
 def main():
     # Environment variables
-    merge_base_sha = os.getenv("MERGE_BASE_SHA", "HEAD")
-    branch_head_sha = os.getenv("BRANCH_HEAD_SHA", "")
-    REQUIRED_ENV_VARS = ["REPO", "REPO_PATH", "ORG", "GH_TOKEN"]
+    REQUIRED_ENV_VARS = ["REPO", "CHANGED_FILES", "ORG", "GH_TOKEN"]
     env_vars = load_env_vars(REQUIRED_ENV_VARS)
 
     gh = github3.login(token=env_vars["GH_TOKEN"])
     repo = gh.repository(owner=env_vars["ORG"], repository=env_vars["REPO"])
 
     # Get changed files
-    changed_files = get_changed_files(merge_base_sha, branch_head_sha, env_vars["REPO_PATH"])
+    changed_files = env_vars["CHANGED_FILES"].split(",")
     print(f"Changed files: {changed_files}")
 
     blacklist_files = get_blacklisted_files(repo)