ci: push the CI image in chunks under Cloudflare's upload limit

.gitea/workflows/ci-image.yml

@@ -20,12 +20,21 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - name: Build
-        run: docker build --pull -t "$IMAGE" .gitea/ci-image
+        # No layer cache, so each rebuild picks up the week's Arch updates.
+        run: docker build --pull --no-cache -t "$IMAGE" .gitea/ci-image
       - name: Push
         # Gitea's Actions token cannot push to the container registry, so this uses an
-        # access token with the write:package scope.
+        # access token with the write:package scope. Cloudflare rejects request bodies over
+        # 100 MB and docker push sends each layer in one request, so regctl pushes the
+        # layers in 50 MB chunks instead.
         env:
           TOKEN: ${{ secrets.PACKAGE_TOKEN }}
         run: |
-          echo "$TOKEN" | docker login git.trivk.dev -u "${{ github.repository_owner }}" --password-stdin
-          docker push "$IMAGE"
+          curl -fsSL -o /usr/local/bin/regctl \
+              https://github.com/regclient/regclient/releases/download/v0.11.7/regctl-linux-amd64
+          echo "3737fbbdd791e04e7a831640b681f3397a376498e80e2ad9b1b2d27296f239bc  /usr/local/bin/regctl" | sha256sum -c
+          chmod +x /usr/local/bin/regctl
+          echo "$TOKEN" | regctl registry login git.trivk.dev -u "${{ github.repository_owner }}" --pass-stdin
+          regctl registry set git.trivk.dev --blob-chunk 52428800 --blob-max 52428800
+          docker save "$IMAGE" -o "$RUNNER_TEMP/image.tar"
+          regctl image import "$IMAGE" "$RUNNER_TEMP/image.tar"