Add docker test suite, include debian 12 to start

.github/workflows/checks.yml

@@ -85,4 +85,24 @@ jobs:
           Write-Output $env:Path
           Get-ChildItem .\vips_w64\vips-dev-8.15
           .\gradlew.bat sample:clean sample:shadowJar
-          java -jar sample/build/libs/sample-all.jar
+          java -jar sample/build/libs/sample-all.jar
+
+  docker-checks:
+    runs-on: ubuntu-24.04
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup Java
+        uses: actions/setup-java@v4
+        with:
+          distribution: "temurin"
+          java-version: 22
+
+      - name: Setup Gradle
+        uses: gradle/actions/setup-gradle@v3
+        with:
+          gradle-version: 8.10.1
+
+      - name: Run checks
+        run: ./run_docker_tests.sh

.gitignore

@@ -16,3 +16,4 @@ hs_err*
 sample_run
 .kotlin
 sample_output*
+sample*.jar

README.md

@@ -7,7 +7,7 @@ and [faster](https://github.com/lopcode/vips-ffm/issues/59#issuecomment-23676349
 
 Supports a vast range of image formats, including HEIC, JXL, WebP, PNG, JPEG, and more. Pronounced "vips (like zips)
 eff-eff-emm". The project is relatively new, but aims to be production ready. Tested on macOS 14, Windows 11, and Linux
-(Ubuntu 24.04). Should work on any architecture you can use libvips and Java on (arm64/amd64/etc).
+(Ubuntu 24.04, Debian 12.1). Should work on any architecture you can use libvips and Java on (arm64/amd64/etc).
 
 Used the library? I'd love to hear from more users - let me know in [Discussions](https://github.com/lopcode/vips-ffm/discussions).
 
@@ -153,6 +153,13 @@ memory: high-water mark 151.24 MB
 [main] INFO vipsffm.SampleRunner - all samples ran successfully 🎉
 ```
 
+### Docker checks
+
+These samples are also run in Docker containers, to verify behaviour on specific Linux distributions. They're useful to
+look at if you're deploying `libvips` and `vips-ffm` workloads using containers.
+
+You can find them in the [`docker_tests`](docker_tests) folder.
+
 ## Native library loading
 
 This library requires the `libvips`, `glib`, and `gobject` native libraries to be present in your library path:

docker_tests/.gitignore

@@ -0,0 +1,2 @@
+*/sample/*
+*/sample/run_samples.sh

docker_tests/debian-12/Dockerfile

@@ -0,0 +1,12 @@
+FROM debian:12.1-slim
+ENV JAVA_HOME=/opt/java/openjdk
+COPY --from=eclipse-temurin:22 $JAVA_HOME $JAVA_HOME
+ENV PATH="${JAVA_HOME}/bin:${PATH}"
+
+COPY sample /opt/sample
+COPY run_samples.sh /opt/run_samples.sh
+
+RUN apt update && apt install libvips-dev -y
+
+WORKDIR /opt
+CMD ./run_samples.sh

run_docker_tests.sh

@@ -0,0 +1,15 @@
+#!/usr/bin/env bash
+set -eou pipefail
+
+echo "building samples..."
+./gradlew sample:clean sample:shadowJar
+
+echo "running docker tests..."
+WORKSPACE_DIR="$PWD"
+
+pushd docker_tests/debian-12
+cp -r "$WORKSPACE_DIR"/sample .
+cp "$WORKSPACE_DIR"/run_samples.sh .
+docker build -t vips-ffm-debian-test .
+docker run vips-ffm-debian-test
+popd

run_samples.sh

@@ -1,8 +1,12 @@
 #!/usr/bin/env bash
 set -eou pipefail
 
-echo "building samples..."
-./gradlew sample:clean sample:shadowJar
+if [ -f "gradlew" ]; then
+  echo "building samples..."
+  ./gradlew sample:clean sample:shadowJar
+else
+  echo "skipping sample build as no gradle present..."
+fi
 
 export JAVA_PATH_OPTS=""
 if [[ "$OSTYPE" == "darwin"* ]]; then