Use a Python script to query the GitHub API to determine base and `…

…head`

.github/workflows/build.yaml

@@ -28,31 +28,61 @@ jobs:
           password: ${{ secrets.GITHUB_TOKEN }}
       - name: Create container name
         id: create-container-info
+        shell: python -u {0}
         run: |
-          base_image=$(echo ${{ github.event.pull_request.base.repo.full_name }} | tr [:upper:] [:lower:])
-          head_image=$(echo ${{ github.event.pull_request.head.repo.full_name }} | tr [:upper:] [:lower:])
-          tag_name="${{ hashFiles('Dockerfile') }}"
-
-          # Default to building a new container under the original repo
-          image_name=$head_image
-          build=true
-
-          # Check if we can use the base image (Nabu Casa)
-          if docker manifest inspect ${{ env.REGISTRY }}/$base_image:$tag_name; then
-            image_name=$base_image
-            build=false
-          fi
-
-          # Check if we can use the head image (PR)
-          if docker manifest inspect ${{ env.REGISTRY }}/$head_image:$tag_name; then
-            image_name=$head_image
-            build=false
-          fi
-
-          echo "build=$build" >> $GITHUB_OUTPUT
-          echo "tag_name=$tag_name" >> $GITHUB_OUTPUT
-          echo "image_name=$image_name" >> $GITHUB_OUTPUT
-          echo "container_name=${{ env.REGISTRY }}/$image_name:$tag_name" >> $GITHUB_OUTPUT
+          import os
+          import json
+          import pathlib
+          import subprocess
+          import urllib.request
+
+          GITHUB_OUTPUT = pathlib.Path(os.environ["GITHUB_OUTPUT"])
+          TAG_NAME = "${{ hashFiles('Dockerfile') }}"
+
+
+          req = urllib.request.Request(
+              url=f"https://api.github.com/repos/{os.environ['REPOSITORY']}",
+              headers={
+                  "Authorization": "token ${{ secrets.GITHUB_TOKEN }}",
+                  "Accept": "application/vnd.github.v3+json",
+                  "X-GitHub-Api-Version": "2022-11-28",
+              }
+          )
+
+          with urllib.request.urlopen(req) as response:
+              assert response.status == 200
+              data = json.loads(response.read().decode())
+
+          head_image = data["full_name"].lower()
+
+          if data["parent"]:
+              base_image = data["parent"]["full_name"].lower()
+          else:
+              base_image = head_image
+
+          image_name = head_image
+          build = True
+
+          for image in {base_image, head_image}:
+              try:
+                  subprocess.run([
+                      "docker", "manifest", "inspect",
+                      f"{os.environ['REGISTRY']}/{image}:{TAG_NAME}"
+                  ], check=True)
+              except subprocess.CalledProcessError:
+                  continue
+              else:
+                  image_name = image
+                  build = False
+                  break
+
+          with GITHUB_OUTPUT.open("a") as f:
+              f.writelines([
+                  f"build={build}\n",
+                  f"tag_name={TAG_NAME}\n",
+                  f"image_name={image_name}\n",
+                  f"container_name={os.environ['REGISTRY']}/{image_name}:{TAG_NAME}\n",
+              ])
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3.3.0
         if: steps.create-container-info.outputs.build == 'true'