Enable Java SDK Distroless container image variants. (apache#33173)

* Enable Java SDK Distroless container image variant

* Add LANG environment and /usr/lib/locale

* Use examples tests instead

.github/trigger_files/beam_PostCommit_Java.json

@@ -1 +1,4 @@
-{}
+{
+  "comment": "Modify this file in a trivial way to cause this test suite to run",
+  "modification": 1
+}

.github/trigger_files/beam_PostCommit_Java_DataflowV2.json

@@ -1,4 +1,4 @@
 {
     "comment": "Modify this file in a trivial way to cause this test suite to run",
-    "modification": 1
+    "modification": 2
 }

runners/google-cloud-dataflow-java/build.gradle

@@ -273,6 +273,69 @@ def createRunnerV2ValidatesRunnerTest = { Map args ->
   }
 }
 
+tasks.register('examplesJavaRunnerV2IntegrationTestDistroless', Test.class) {
+  group = "verification"
+  dependsOn 'buildAndPushDistrolessContainerImage'
+  def javaVer = project.findProperty('testJavaVersion')
+  def repository = "us.gcr.io/apache-beam-testing/${System.getenv('USER')}"
+  def tag = project.findProperty('dockerTag')
+  def imageURL = "${repository}/beam_${javaVer}_sdk_distroless:${tag}"
+  def pipelineOptions = [
+          "--runner=TestDataflowRunner",
+          "--project=${gcpProject}",
+          "--region=${gcpRegion}",
+          "--tempRoot=${dataflowValidatesTempRoot}",
+          "--sdkContainerImage=${imageURL}",
+          "--experiments=use_unified_worker,use_runner_v2",
+          "--firestoreDb=${firestoreDb}",
+  ]
+  systemProperty "beamTestPipelineOptions", JsonOutput.toJson(pipelineOptions)
+
+  include '**/*IT.class'
+
+  maxParallelForks 4
+  classpath = configurations.examplesJavaIntegrationTest
+  testClassesDirs = files(project(":examples:java").sourceSets.test.output.classesDirs)
+  useJUnit { }
+}
+
+tasks.register('buildAndPushDistrolessContainerImage', Task.class) {
+  // Only Java 17 and 21 are supported.
+  // See https://github.com/GoogleContainerTools/distroless/tree/main/java#image-contents.
+  def allowed = ["java17", "java21"]
+  doLast {
+    def javaVer = project.findProperty('testJavaVersion')
+    if (!allowed.contains(javaVer)) {
+      throw new GradleException("testJavaVersion must be one of ${allowed}, got: ${javaVer}")
+    }
+    if (!project.hasProperty('dockerTag')) {
+      throw new GradleException("dockerTag is missing but required")
+    }
+    def repository = "us.gcr.io/apache-beam-testing/${System.getenv('USER')}"
+    def tag = project.findProperty('dockerTag')
+    def imageURL = "${repository}/beam_${javaVer}_sdk_distroless:${tag}"
+    exec {
+      executable 'docker'
+      workingDir rootDir
+      args = [
+              'buildx',
+              'build',
+              '-t',
+              imageURL,
+              '-f',
+              'sdks/java/container/Dockerfile-distroless',
+              "--build-arg=BEAM_BASE=gcr.io/apache-beam-testing/beam-sdk/beam_${javaVer}_sdk",
+              "--build-arg=DISTROLESS_BASE=gcr.io/distroless/${javaVer}-debian12",
+              '.'
+      ]
+    }
+    exec {
+      executable 'docker'
+      args = ['push', imageURL]
+    }
+  }
+}
+
 // Push docker images to a container registry for use within tests.
 // NB: Tasks which consume docker images from the registry should depend on this
 // task directly ('dependsOn buildAndPushDockerJavaContainer'). This ensures the correct

sdks/java/container/Dockerfile-distroless

@@ -0,0 +1,42 @@
+###############################################################################
+#  Licensed to the Apache Software Foundation (ASF) under one
+#  or more contributor license agreements.  See the NOTICE file
+#  distributed with this work for additional information
+#  regarding copyright ownership.  The ASF licenses this file
+#  to you under the Apache License, Version 2.0 (the
+#  "License"); you may not use this file except in compliance
+#  with the License.  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+# limitations under the License.
+###############################################################################
+
+# ARG BEAM_BASE is the Beam SDK container image built using sdks/python/container/Dockerfile.
+ARG BEAM_BASE
+
+# ARG DISTROLESS_BASE is the distroless container image URL. For available distroless Java images,
+#   see https://github.com/GoogleContainerTools/distroless/tree/main?tab=readme-ov-file#what-images-are-available.
+#   Only Java versions 17 and 21 are supported.
+ARG DISTROLESS_BASE
+FROM ${BEAM_BASE} AS base
+ARG TARGETARCH
+ENV LANG C.UTF-8
+
+LABEL Author="Apache Beam <[email protected]>"
+
+RUN if [ -z "${TARGETARCH}" ]; then echo "fatal: TARGETARCH not set; run as docker buildx build or use --build-arg=TARGETARCH=amd64|arm64" >&2; exit 1; fi
+
+FROM ${DISTROLESS_BASE}:latest-${TARGETARCH} AS distroless
+
+COPY --from=base /opt /opt
+
+# Along with the LANG environment variable above, prevents internally discovered failing bugs related to Dataflow Flex
+# template character encodings.
+COPY --from=base /usr/lib/locale /usr/lib/locale
+
+ENTRYPOINT ["/opt/apache/beam/boot"]