fix: add universal image to build and push list (#329)

* fix: add universal image to build and push list

The universal image was added in #307 but never included in
the IMAGES array in scripts/images.sh, so it was never built
or pushed to Docker Hub.

* fix: support per-image platform override, restrict universal to amd64

The devcontainers/universal base image is amd64-only. Add support
for a .platforms file per image directory to override the default
multi-arch platform list.

Author: matifali

images/universal/.platforms

@@ -0,0 +1 @@
+linux/amd64

scripts/build_images.sh

@@ -88,6 +88,8 @@ if [ $QUIET = true ]; then
   )
 fi
 
+DEFAULT_PLATFORM="linux/amd64,linux/arm64"
+
 for image in "${IMAGES[@]}"; do
   image_dir="$PROJECT_ROOT/images/$image"
   image_file="${TAG}.Dockerfile"
@@ -102,7 +104,13 @@ for image in "${IMAGES[@]}"; do
     continue
   fi
 
-  run_trace $DRY_RUN depot build --project "gb3p8xrshk" --load --platform linux/amd64,linux/arm64 --save --metadata-file="build_${image}.json" \
+  # Allow per-image platform override via a .platforms file.
+  platform="$DEFAULT_PLATFORM"
+  if [ -f "$image_dir/.platforms" ]; then
+    platform=$(cat "$image_dir/.platforms")
+  fi
+
+  run_trace $DRY_RUN depot build --project "gb3p8xrshk" --load --platform "$platform" --save --metadata-file="build_${image}.json" \
     "${docker_flags[@]}" \
     "$image_dir" \
     --file="$image_path" \

scripts/images.sh

@@ -10,4 +10,5 @@ IMAGES=(
   "java"
   "node"
   "desktop"
+  "universal"
 )