ci: reattempt docker image caching

Author: Frank Bell

.github/init-image/action.yaml

@@ -0,0 +1,43 @@
+name: init image
+description: |
+  This action initializes a Docker image within a runner.
+
+inputs:
+  image:
+    description: The image to be initialized
+    # Image can be edited at https://github.com/use-ink/docker-images
+    default: evilrobot/useink:pr-4-stable
+
+runs:
+  using: composite
+
+  steps:
+    - name: Get latest image digest
+      id: image-digest
+      shell: bash
+      run: |
+        DIGEST=$(docker manifest inspect ${{ inputs.image }} | jq -r '.config.digest')
+        echo "digest=$DIGEST" >> $GITHUB_OUTPUT
+
+    - name: Cache image
+      id: cache-image
+      uses: actions/cache@v4
+      with:
+        path: ./docker-cache
+        # Include digest in the cache key to detect updates
+        key: docker-images-${{ runner.os }}-${{ inputs.image }}
+
+    - name: Load image from cache
+      if: steps.cache-image.outputs.cache-hit == 'true'
+      shell: bash
+      run: |
+        mkdir -p ./docker-cache
+        docker load < ./docker-cache/image.tar
+
+    - name: Pull and cache image
+      if: steps.cache-image.outputs.cache-hit != 'true'
+      shell: bash
+      run: |
+        mkdir -p ./docker-cache
+        docker pull ${{ inputs.image }}
+        docker save ${{ inputs.image }} > ./docker-cache/image.tar

.github/run-container-command/action.yaml

@@ -1,6 +1,6 @@
 name: run container command
 description: |
-  This action runs a specified command within a container using an optionally specified image.
+  This action runs a specified command within a container (using the `useink/ci` image).
 
 inputs:
   command:
@@ -14,46 +14,8 @@ runs:
   using: composite
 
   steps:
-
-    - name: Set image
-      id: set-image
-      shell: bash
-      # Image can be edited at https://github.com/use-ink/docker-images
-      # NOTE: also needs to be manually updated within the `uses` property of the 'Run command in container' step below
-      # due to being unable to use env, steps context in setting that property value.
-      run: echo "IMAGE=evilrobot/useink:pr-4-stable" >> "${GITHUB_OUTPUT}"
-
-    - name: Get latest image digest
-      id: image-digest
-      shell: bash
-      run: |
-        DIGEST=$(docker manifest inspect ${{ steps.set-image.outputs.IMAGE }} | jq -r '.config.digest')
-        echo "digest=$DIGEST" >> $GITHUB_OUTPUT
-
-    - name: Cache image
-      id: cache-docker
-      uses: actions/cache@v4
-      with:
-        path: ./docker-cache
-        # Include digest in the cache key to detect updates
-        key: docker-images-${{ runner.os }}-${{ steps.image-digest.outputs.digest }}
-
-    - name: Load image from cache
-      if: steps.cache-docker.outputs.cache-hit == 'true'
-      shell: bash
-      run: |
-        mkdir -p ./docker-cache
-        docker load < ./docker-cache/image.tar
-
-    - name: Pull and cache image
-      if: steps.cache-docker.outputs.cache-hit != 'true'
-      shell: bash
-      run: |
-        mkdir -p ./docker-cache
-        docker pull ${{ steps.set-image.outputs.IMAGE }}
-        docker save ${{ steps.set-image.outputs.IMAGE }} > ./docker-cache/image.tar
-
     - name: Run command in container
+      # Image can be edited at https://github.com/use-ink/docker-images
       uses: docker://evilrobot/useink:pr-4-stable
       env:
         CARGO_TARGET_DIR: "/github/workspace/${{ env.CARGO_TARGET_DIR }}"

.github/workflows/ci.yml

@@ -59,6 +59,9 @@ jobs:
         with:
           fetch-depth: 1
 
+      - name: Initialize image
+        uses: ./.github/init-image
+
       - name: Output environment information
         uses: ./.github/run-container-command
         with:
@@ -80,6 +83,9 @@ jobs:
         with:
           fetch-depth: 1
 
+      - name: Initialize image
+        uses: ./.github/init-image
+
       - name: Check Spelling
         uses: ./.github/run-container-command
         with: