feat: reduce container size (#4)

Author: jveldboom

.github/workflows/pull-request.yaml

@@ -9,8 +9,44 @@ on:
 jobs:
   build:
     runs-on: ubuntu-latest
+    env:
+      IMAGE_INPUT_FILE: ./samples/bees.png
+      IMAGE_OUTPUT_FILE: ./samples/bees-out-pr.jpg
     steps:
       - uses: actions/checkout@v6
 
       - name: Build image
-        run: docker build .
+        run: docker build -t docker-google-guetzli .
+
+      - name: Run image
+        run: |
+          docker run --rm -v $(pwd):/data docker-google-guetzli \
+            --quality 85 ${{ env.IMAGE_INPUT_FILE }} ${{ env.IMAGE_OUTPUT_FILE }}
+
+      - name: Validate output
+        run: |
+          if [ ! -f ${{ env.IMAGE_OUTPUT_FILE }} ]; then
+            echo "ERROR: output file does not exist"
+            exit 1
+          fi
+
+          if [ ! -s ${{ env.IMAGE_OUTPUT_FILE }} ]; then
+            echo "ERROR: output file is empty"
+            exit 1
+          fi
+
+          input_size=$(stat -c%s ${{ env.IMAGE_INPUT_FILE }})
+          output_size=$(stat -c%s ${{ env.IMAGE_OUTPUT_FILE }})
+
+          if [ "$output_size" -ge "$input_size" ]; then
+            echo "ERROR: output file ($output_size bytes) is not smaller than input ($input_size bytes)"
+            exit 1
+          fi
+
+          mime_type=$(file --mime-type -b ${{ env.IMAGE_OUTPUT_FILE }})
+          if [ "$mime_type" != "image/jpeg" ]; then
+            echo "ERROR: output file has unexpected MIME type: $mime_type (expected image/jpeg)"
+            exit 1
+          fi
+
+          echo "OK: $input_size bytes -> $output_size bytes"

Dockerfile

@@ -1,6 +1,4 @@
-FROM alpine:latest
-
-WORKDIR /opt/google
+FROM alpine:3.21 AS builder
 
 RUN apk --no-cache add \
     libpng-dev \
@@ -12,10 +10,21 @@ ARG VERSION="v1.0.1"
 
 RUN git clone https://github.com/google/guetzli.git \
     --branch "${VERSION}" \
-    --depth 1
+    --depth 1 \
+    /opt/google/guetzli
+
+RUN cd /opt/google/guetzli && make
+
+
+FROM alpine:3.21
+
+RUN apk --no-cache add \
+    libpng \
+    libstdc++ \
+    libgcc
 
-RUN cd guetzli && make
+COPY --from=builder /opt/google/guetzli/bin/Release/guetzli /usr/local/bin/guetzli
 
 WORKDIR /data
 
-ENTRYPOINT ["/opt/google/guetzli/bin/Release/guetzli"]
+ENTRYPOINT ["guetzli"]

README.md

@@ -12,25 +12,30 @@ docker run --rm -v $(pwd):/data ghcr.io/jveldboom/docker-google-guetzli:latest \
 ## Run Examples
 ```sh
 docker run --rm -v $(pwd):/data ghcr.io/jveldboom/docker-google-guetzli:latest \
-  --quality 85 ./samples/bees.png ./samples/bees-out.png
+  --quality 85 ./samples/bees.png ./samples/bees-out.jpg
 ```
 
 Original | Processed with 85%
 :------------: | :-------------:
-![Original](./samples/bees.png)<br>177 KB | ![Original](./samples/bees-out.png)<br> 22 KB
-![Original](./samples/rose.jpg)<br>219 KB  | ![Original](./samples/rose-out.png)<br> 103 KB
+![Original](./samples/bees.png)<br>177 KB | ![Processed](./samples/bees-out.jpg)<br> 22 KB
+![Original](./samples/rose.jpg)<br>219 KB  | ![Processed](./samples/rose-out.jpg)<br> 103 KB
+
+## Performance
+Guetzli is intentionally slow — it tries many encodings to find the best compression. Expect processing to take **1 minute or more per megapixel**. It is best suited for batch or offline processing, not real-time use.
 
-## TODO
-- [ ] create pull request workflow
-- [ ] include .dockerignore to reduce image size
-- [ ] see if we can reduce overall container size
+It also requires a minimum of **300 MB of memory per megapixel** of input image.
 
+## Contributing
+
+### Build the image locally
 ```sh
-# dockerfile
-apk add --no-cache --virtual .build-deps
+# build the image locally
+docker build -t docker-google-guetzli .
 
-...
+# run locally built image
+docker run --rm -v $(pwd):/data docker-google-guetzli \
+  --quality 85 ./samples/bees.png ./samples/bees-out.png
 
-apk del --no-cache .build-deps
-rm -rf /var/tmp/* /tmp/* /opt/build
+# check size
+docker image ls docker-google-guetzli
 ```