Create new buildx builder to allow remote registry caching

Author: FluxCapacitor2

.github/workflows/release.yml

@@ -32,6 +32,13 @@ jobs:
         if: ${{ inputs.environment == 'staging' }}
         run: docker login -u '${{ secrets.DOCKER_USERNAME_STAGING }}' -p '${{ secrets.DOCKER_PASSWORD_STAGING }}' registry.anvil.rcac.purdue.edu
 
+        # This step is necessary because our script uses the destination OCI registry as a layer cache, which isn't supported by Docker out of the box.
+        # See https://docs.docker.com/build/cache/backends/registry/ and https://docs.docker.com/build/builders/drivers/ for more info.
+      - name: Set up buildx builder
+        run: |
+          docker buildx create --use
+          docker buildx inspect --bootstrap
+
       - name: Release
         run: ./.github/workflows/scripts/release-${{ inputs.environment }}.sh "${{ inputs.version }}"
         env:

.github/workflows/scripts/release.sh

@@ -51,13 +51,13 @@ build_and_push() {
 
   IIDFILE=$(mktemp)
 
-  docker build \
+  docker buildx build \
     --push \
     -f "$DOCKERFILE" \
     --iidfile "$IIDFILE" \
     -t "$IMAGE_TAG" \
     --cache-from="type=registry,ref=$CACHE_TAG" \
-    --cache-to="type=registry,ref=$CACHE_TAG" \
+    --cache-to="type=registry,ref=$CACHE_TAG,mode=max" \
     "$BUILD_CONTEXT"
 
   IMAGE_ID=$(cat "$IIDFILE") # looks like "sha256:32975dcafd44d8c6f921d2276e2a39f42f268e8c9584d6c4d4c88f5a073b7b1d"