cache langfuse docker images in ci

Author: hassiebp

.github/workflows/ci.yml

@@ -150,6 +150,37 @@ jobs:
           curl -fsSL "https://raw.githubusercontent.com/langfuse/langfuse/${LANGFUSE_SERVER_SHA}/docker-compose.yml" \
             -o ./langfuse-server/docker-compose.yml
           echo "${LANGFUSE_SERVER_SHA}"
+      - name: Resolve langfuse server image digests
+        run: |
+          docker compose -f ./langfuse-server/docker-compose.yml config --images \
+            | tee ./langfuse-server/docker-images.txt
+
+          while read -r image; do
+            docker manifest inspect "$image" \
+              | jq -r --arg image "$image" '
+                  if .manifests then
+                    .manifests[]
+                    | select(.platform.os == "linux" and .platform.architecture == "amd64")
+                    | "\($image)@\(.digest)"
+                  else
+                    "\($image)@\(.config.digest // .Descriptor.digest // .digest)"
+                  end
+                '
+          done < ./langfuse-server/docker-images.txt \
+            | tee ./langfuse-server/docker-image-digests.txt
+      - name: Restore langfuse server image cache
+        id: docker-image-cache
+        uses: actions/cache@668228422ae6a00e4ad889ee87cd7109ec5666a7 # v5
+        with:
+          path: ./langfuse-server/docker-image-cache
+          key: langfuse-docker-${{ runner.os }}-${{ hashFiles('langfuse-server/docker-compose.yml', 'langfuse-server/docker-image-digests.txt') }}
+      - name: Load cached langfuse server images
+        if: ${{ steps.docker-image-cache.outputs.cache-hit == 'true' }}
+        run: |
+          shopt -s nullglob
+          for image_tar in ./langfuse-server/docker-image-cache/*.tar; do
+            docker load -i "$image_tar"
+          done
 
       - name: Run langfuse server
         run: |
@@ -167,6 +198,14 @@ jobs:
           LANGFUSE_ENABLE_EVENTS_TABLE_OBSERVATIONS=true \
           docker compose up -d
           echo "::endgroup::"
+      - name: Save langfuse server images to cache
+        if: ${{ steps.docker-image-cache.outputs.cache-hit != 'true' && matrix.shard-name == 'core' }}
+        run: |
+          mkdir -p ./langfuse-server/docker-image-cache
+          while read -r image; do
+            safe_name=$(echo "$image" | tr '/:.' '_')
+            docker save -o "./langfuse-server/docker-image-cache/${safe_name}.tar" "$image"
+          done < ./langfuse-server/docker-images.txt
 
       - name: Health check for langfuse server
         run: |