WIP using jlink and jdeps to build docker image

ojp-server/README.md

@@ -1,8 +1,25 @@
 ## Docker Image
 
-### Build docker image locally
+The base image is a custom Alpine JRE built with `jlink` (only the modules required by OJP), bringing the final image size to **128MB**.
 
-> mvn compile jib:dockerBuild
+### Build the base image (first time or when dependencies change)
+
+```bash
+# From the repository root
+docker build -f ojp-server/base.Dockerfile -t rrobetti/ojp-base:jre24-alpine .
+```
+
+### Build the app image locally
+
+```bash
+mvn -pl ojp-server/ jib:dockerBuild -Djib.from.image=docker://rrobetti/ojp-base:jre24-alpine
+```
+
+### Run locally
+
+```bash
+docker run -p 1059:1059 rrobetti/ojp:0.4.9-SNAPSHOT
+```
 
 ### Build and push to Docker Hub
 PS: Only authorized users.

ojp-server/base.Dockerfile

@@ -0,0 +1,14 @@
+FROM eclipse-temurin:24-jdk-alpine AS jre-build
+
+RUN jlink \
+    --add-modules java.base,java.compiler,java.desktop,java.management,java.naming,java.rmi,java.scripting,java.security.jgss,java.sql,jdk.httpserver,jdk.unsupported \
+    --strip-debug \
+    --no-man-pages \
+    --no-header-files \
+    --compress=zip-6 \
+    --output /custom-jre
+
+FROM alpine:3.21
+ENV JAVA_HOME=/opt/java
+ENV PATH="${JAVA_HOME}/bin:${PATH}"
+COPY --from=jre-build /custom-jre $JAVA_HOME