squash-me, implement read-only cache for pull requests; undo hardcode…

…d params in Makefile

.github/workflows/build-notebooks-TEMPLATE.yaml

@@ -19,7 +19,12 @@ name: Build & Publish Notebook Servers (TEMPLATE)
 jobs:
   build:
     runs-on: ubuntu-latest
+    env:
+      # GitHub image registry used for storing $(CONTAINER_ENGINE)'s cache
+      CACHE: "ghcr.io/${{ github.repository }}/workbench-images/build-cache"
+
     steps:
+
       - uses: actions/checkout@v4
 
       - name: Login to GitHub Container Registry
@@ -67,7 +72,7 @@ jobs:
         env:
           IMAGE_TAG: "${{ github.ref_name }}_${{ github.sha }}"
           IMAGE_REGISTRY: "ghcr.io/${{ github.repository }}/workbench-images"
-          CACHE: "ghcr.io/${{ github.repository }}/workbench-images/build-cache"
+          CONTAINER_BUILD_CACHE_ARGS: "--cache-from ${{ env.CACHE }} --cache-to ${{ env.CACHE }}"
 
       # https://docs.github.com/en/actions/using-workflows/events-that-trigger-workflows#pull_request
       - name: "pull_request: make ${{ inputs.target }}"
@@ -76,7 +81,7 @@ jobs:
         env:
           IMAGE_TAG: "${{ github.head_ref }}_${{ github.sha }}"
           IMAGE_REGISTRY: "ghcr.io/${{ github.repository }}/workbench-images/pr${{ fromJson(inputs.github).event.number }}"
-          CACHE: "ghcr.io/${{ github.repository }}/workbench-images/build-cache"
+          CONTAINER_BUILD_CACHE_ARGS: "--cache-from ${{ env.CACHE }}"
 
       - run: df -h
         if: "${{ !cancelled() }}"

Makefile

@@ -1,5 +1,7 @@
 IMAGE_REGISTRY   ?= quay.io/opendatahub/workbench-images
 RELEASE	 		 ?= 2024a
+# additional user-specified caching parameters for $(CONTAINER_ENGINE) build
+CONTAINER_BUILD_CACHE_ARGS ?= --no-cache
 
 # OS dependant: Generate date, select appropriate cmd to locate container engine
 ifeq ($(OS), Windows_NT)
@@ -41,7 +43,7 @@ define build_image
 		$(eval BUILD_ARGS := --build-arg BASE_IMAGE=$(BASE_IMAGE_NAME)),
 		$(eval BUILD_ARGS :=)
 	)
-	$(CONTAINER_ENGINE) build --cache-from $(CACHE) --cache-to $(CACHE) -t $(IMAGE_NAME) $(BUILD_ARGS) $(2)
+	$(CONTAINER_ENGINE) build $(CONTAINER_BUILD_CACHE_ARGS)  -t $(IMAGE_NAME) $(BUILD_ARGS)  $(2)
 endef
 
 # Push function for the notebok image: