chore: migrate ZooKeeper images and builds to Java 25 (#68)

Update Java runtimes, Kotlin bytecode targets, CodeQL, and release metadata to Java 25. Require Java 25 and verify the zu helper starts in image smoke tests.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: amuraru

.github/workflows/codeql.yml

@@ -49,11 +49,11 @@ jobs:
       with:
         go-version-file: go.mod
 
-    - name: Set up JDK 21
+    - name: Set up JDK 25
       if: matrix.language == 'java'
       uses: actions/setup-java@v6
       with:
-        java-version: '21'
+        java-version: '25'
         distribution: 'temurin'
 
     - name: Initialize CodeQL

.github/workflows/release.yml

@@ -119,8 +119,8 @@ jobs:
             type=raw,value=${{ needs.prepare.outputs.zk_version }}-apache-${{ needs.prepare.outputs.tag }}
             type=raw,value=${{ needs.prepare.outputs.zk_version }}-apache
           labels: |
-            org.opencontainers.image.description=Apache Zookeeper ${{ needs.prepare.outputs.zk_version }} with OpenJDK 21
-      # Rebuilt on every release, so it also picks up the latest JDK 21 patch
+            org.opencontainers.image.description=Apache Zookeeper ${{ needs.prepare.outputs.zk_version }} with OpenJDK 25
+      # Rebuilt on every release, so it also picks up the latest JDK 25 patch
       # release and Debian security updates.
       - name: Build and push zookeeper Apache image
         id: build-zk-apache
@@ -153,7 +153,7 @@ jobs:
           tags: |
             type=raw,value=${{ needs.prepare.outputs.zk_version }}-${{ needs.prepare.outputs.tag }}
           labels: |
-            org.opencontainers.image.description=Apache Zookeeper image build with java-21
+            org.opencontainers.image.description=Apache Zookeeper image build with java-25
       - name: Build and push zookeeper image
         id: build-zk
         uses: docker/build-push-action@v7

.github/workflows/zookeeper-images.yaml

@@ -87,8 +87,16 @@ jobs:
         run: |
           docker run --rm --entrypoint bash -e ZK_VERSION zookeeper:ci -ec '
             java -version
+            java -XshowSettings:properties -version 2>&1 | grep -Eq "^[[:space:]]*java.specification.version = 25$"
             zkServer.sh version 2>/dev/null | tee /dev/stderr | grep -q "${ZK_VERSION}"
             test -s /opt/libs/zu.jar
+            set +e
+            zu_output="$(java -jar /opt/libs/zu.jar 2>&1)"
+            zu_status=$?
+            set -e
+            printf "%s\n" "$zu_output"
+            test "$zu_status" -eq 1
+            [[ "$zu_output" == "Usage: zu "* ]]
             for s in zookeeperStart.sh zookeeperReady.sh zookeeperLive.sh zookeeperTeardown.sh zookeeperMetrics.sh; do
               test -x "/usr/local/bin/${s}"
             done

docker/Dockerfile

@@ -9,15 +9,15 @@
 #     http://www.apache.org/licenses/LICENSE-2.0
 #
 
-# Base Apache ZooKeeper + OpenJDK 21 image built from docker/zookeeper-image.
+# Base Apache ZooKeeper + OpenJDK 25 image built from docker/zookeeper-image.
 # It is not pinned here: the build-zookeeper release job builds that image
 # first and passes its digest in, so both always come from the same commit
 # and ARG ZK_VERSION. For local builds use `make build-zk-image`.
 ARG BASE_IMAGE
 
 # zu.jar is architecture-independent bytecode, so build it once on the native
 # build platform instead of re-running Gradle under emulation for every target.
-FROM --platform=$BUILDPLATFORM gradle:jdk21 AS zu-builder
+FROM --platform=$BUILDPLATFORM gradle:jdk25 AS zu-builder
 
 RUN mkdir /zu
 COPY zu /zu
@@ -34,7 +34,7 @@ RUN apt-get -q update && \
 
 # OCI standard labels
 LABEL org.opencontainers.image.title="Apache Zookeeper"
-LABEL org.opencontainers.image.description="Apache Zookeeper image build with java-21"
+LABEL org.opencontainers.image.description="Apache Zookeeper image build with java-25"
 LABEL org.opencontainers.image.source="https://github.com/adobe/zookeeper-operator"
 LABEL org.opencontainers.image.url="https://github.com/adobe/zookeeper-operator"
 LABEL org.opencontainers.image.documentation="https://github.com/adobe/zookeeper-operator"

docker/zookeeper-image/Dockerfile

@@ -8,24 +8,24 @@ RUN set -eux; \
 	; \
 	rm -rf /var/lib/apt/lists/*
 
-ENV JAVA_HOME=/usr/local/openjdk-21
+ENV JAVA_HOME=/usr/local/openjdk-25
 ENV PATH=$JAVA_HOME/bin:$PATH
 
 # Default to UTF-8 file.encoding
 ENV LANG=C.UTF-8
-ENV JAVA_VERSION=21
+ENV JAVA_VERSION=25
 
 RUN set -eux; \
 	\
 	arch="$(dpkg --print-architecture)"; \
 	case "$arch" in \
 		'amd64') \
-			downloadUrl='https://download.oracle.com/java/21/latest/jdk-21_linux-x64_bin.tar.gz'; \
-			downloadSha256='https://download.oracle.com/java/21/latest/jdk-21_linux-x64_bin.tar.gz.sha256'; \
+			downloadUrl='https://download.oracle.com/java/25/latest/jdk-25_linux-x64_bin.tar.gz'; \
+			downloadSha256='https://download.oracle.com/java/25/latest/jdk-25_linux-x64_bin.tar.gz.sha256'; \
 			;; \
 		'arm64') \
-			downloadUrl='https://download.oracle.com/java/21/latest/jdk-21_linux-aarch64_bin.tar.gz'; \
-			downloadSha256='https://download.oracle.com/java/21/latest/jdk-21_linux-aarch64_bin.tar.gz.sha256'; \
+			downloadUrl='https://download.oracle.com/java/25/latest/jdk-25_linux-aarch64_bin.tar.gz'; \
+			downloadSha256='https://download.oracle.com/java/25/latest/jdk-25_linux-aarch64_bin.tar.gz.sha256'; \
 			;; \
 		*) echo >&2 "error: unsupported architecture: '$arch'"; exit 1 ;; \
 	esac; \
@@ -163,7 +163,7 @@ ENV PATH=$PATH:/$DISTRO_NAME/bin \
 
 # OCI standard labels
 LABEL org.opencontainers.image.title="Apache Zookeeper"
-LABEL org.opencontainers.image.description="Apache Zookeeper ${ZK_VERSION} with OpenJDK 21"
+LABEL org.opencontainers.image.description="Apache Zookeeper ${ZK_VERSION} with OpenJDK 25"
 LABEL org.opencontainers.image.source="https://github.com/adobe/zookeeper-operator"
 LABEL org.opencontainers.image.url="https://github.com/adobe/zookeeper-operator"
 LABEL org.opencontainers.image.documentation="https://github.com/adobe/zookeeper-operator"

docker/zu/build.gradle.kts

@@ -12,8 +12,8 @@ repositories {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_21
-    targetCompatibility = JavaVersion.VERSION_21
+    sourceCompatibility = JavaVersion.VERSION_25
+    targetCompatibility = JavaVersion.VERSION_25
 }
 
 dependencies {
@@ -30,6 +30,6 @@ tasks.withType<ShadowJar>() {
 
 tasks.withType<KotlinCompile> {
   compilerOptions {
-    jvmTarget.set(JvmTarget.JVM_21)
+    jvmTarget.set(JvmTarget.JVM_25)
   }
 }