Add external PR labeler action

.github/workflows/external_pr_labeler.yml

@@ -0,0 +1,39 @@
+name: External PR labeler
+
+on:
+  pull_request_target:
+#   types:
+#     - opened
+
+jobs:
+  label_prs:
+    name: Label external PRs
+    runs-on: ubuntu-latest
+    permissions: read-all
+    steps:
+#     - id: is_member
+#       name: Check if author is an org member
+#       run: |
+#         curl -L \
+#           -H "Accept: application/vnd.github+json" \
+#           -H "Authorization: Bearer ${{ secrets.GITHUB_TOKEN }}" \
+#           -H "X-GitHub-Api-Version: 2022-11-28" \
+#           https://api.github.com/orgs/uyuni-project/members/${{ github.actor }}
+
+      - id: is_member
+        name: Check if author is an org member
+        env:
+          GH_TOKEN: ${{ secrets.ORG_READ_TOKEN }}
+        run: |
+          # The following API call returns 404 if user is not a member of org
+          # See: https://docs.github.com/rest/orgs/members#check-organization-membership-for-a-user--status-codes
+          RESULT=`gh api orgs/uyuni-project/members/does_not_exist -i | head -1 | awk '{ print $2 }'`
+          echo "result=$RESULT" >> "$GITHUB_OUTPUT"
+      - name: Label the PR
+        # If not a member of org
+        if: ${{ steps.is_member.outputs.result == 404 }}
+        uses: christianvuerings/add-labels@v1
+        with:
+          labels: "external-contrib"
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}