Add example to test transitive compile-time dependencies in Gradle

jjohannes · jjohannes · commit bdce04c6df3e · 2025-04-10T08:04:03.000+02:00
This adds an example that show that the Gradle Metadata published
for Log4j has the desired effect on the compile classpath when
Log4j is used in Gradle builds.

This changes the "Android test pipeline" to a "Gradle test pipeline"
to run all Gradle-based tests. Which are at the moment the
"Android test" and this newly added test.

Signed-off-by: Jendrik Johannes &lt;jendrik.johannes@gmail.com&gt;
diff --git a/.github/workflows/gradle-reusable-test.yaml b/.github/workflows/gradle-reusable-test.yaml
@@ -38,7 +38,7 @@ permissions: read-all
 
 jobs:
 
-  android-test:
+  gradle-test:
 
     runs-on: ubuntu-latest
 
@@ -64,6 +64,17 @@ jobs:
           develocity-url: https://develocity.apache.org
           develocity-plugin-version: 3.18.2
 
+      - name: Test log4j-samples-gradle-metadata
+        id: build
+        shell: bash
+        env:
+          LOG4J_VERSION: ${{ inputs.log4j-version }}
+          LOG4J_REPOSITORY_URL: ${{ inputs.log4j-repository-url }}
+        run: |
+          ./gradlew \
+          -Plog4j.version=$LOG4J_VERSION \
+          -Plog4j.repository.url=$LOG4J_REPOSITORY_URL \
+          :app:build :app:connectedCheck
 
       - name: Enable KVM
         run: |
@@ -112,18 +123,17 @@ jobs:
             sleep 1
           done
 
-      - name: Build
+      - name: Test log4j-samples-android
         id: build
         shell: bash
         env:
           LOG4J_VERSION: ${{ inputs.log4j-version }}
           LOG4J_REPOSITORY_URL: ${{ inputs.log4j-repository-url }}
         run: |
-          log4j-samples-android/gradlew -p log4j-samples-android \
-          --console plain \
+          ./gradlew \
           -Plog4j.version=$LOG4J_VERSION \
           -Plog4j.repository.url=$LOG4J_REPOSITORY_URL \
-          build connectedCheck
+          :app:build :app:connectedCheck
 
       - name: Remove AVD Device
         if: ${{ always() && env.EMULATOR_STARTED == 'true' }}
diff --git a/.github/workflows/integration-test.yaml b/.github/workflows/integration-test.yaml
@@ -65,8 +65,8 @@ jobs:
       ref: ${{ inputs.samples-ref }}
       test-report-suffix: '-it'
 
-  android-test:
-    uses: apache/logging-log4j-samples/.github/workflows/android-reusable-test.yaml@main
+  gradle-test:
+    uses: apache/logging-log4j-samples/.github/workflows/gradle-reusable-test.yaml@main
     with:
       log4j-version: ${{ inputs.log4j-version }}
       log4j-repository-url: ${{ inputs.log4j-repository-url }}
diff --git a/.gitignore b/.gitignore
@@ -17,6 +17,9 @@
 target/
 .flattened-pom.xml
 /.mvn/wrapper/maven-wrapper.jar
+# Gradle
+.gradle/
+build/
 # IDEA
 .idea/
 *.iml
diff --git a/README.adoc b/README.adoc
@@ -33,6 +33,9 @@ Explains how to send logs to https://flume.apache.org[Apache Flume].
 xref:log4j-samples-graalvm/README.adoc[`log4j-samples-graalvm`]::
 Explains how to use Log4j API and its implementation to create native GraalVM images.
 
+xref:log4j-samples-gradle-metadata/README.adoc[`log4j-samples-gradle-metadata`]::
+Shows how strict compile classpath or module path checking can be enabled for compilation in Gradle when Log4j is used and that all required annotation libraries are available.
+
 xref:log4j-samples-jlink/README.adoc[`log4j-samples-jlink`]::
 An example of JLink custom JRE.
 
diff --git a/gradle.properties b/gradle.properties
@@ -15,6 +15,10 @@
 # limitations under the License.
 #
 ##
+
+# Enable assertions
+org.gradle.jvmargs=-ea
+
 # Required by AndroidX dependencies
 android.useAndroidX = true
 
diff --git a/gradle/wrapper/gradle-wrapper.jar b/gradle/wrapper/gradle-wrapper.jar
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
diff --git a/gradlew b/gradlew
diff --git a/gradlew.bat b/gradlew.bat
diff --git a/log4j-samples-android/README.adoc b/log4j-samples-android/README.adoc
@@ -25,10 +25,10 @@ To build the project, run:
 
 [source,shell]
 ----
-./gradlew build
+./gradlew :app:build
 ----
 
-inside this directory.
+in the samples repository root.
 
 Since version `2.25.0` this application is part of the integration tests for a Log4j release.
 
diff --git a/log4j-samples-android/app/build.gradle b/log4j-samples-android/app/build.gradle
@@ -15,7 +15,7 @@
  * limitations under the License.
  */
 plugins {
-    id 'com.android.application'
+    id 'com.android.application' version '8.8.2'
 }
 
 android {
diff --git a/log4j-samples-gradle-metadata/README.adoc b/log4j-samples-gradle-metadata/README.adoc
@@ -0,0 +1,30 @@
+////
+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
+
+    https://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.
+////
+= Apache Log4j Samples: Gradle Metadata Consumption
+
+This project is an example that validates that, when used in Gradle, Log4j provides transitive dependencies to annotation libraries on the compile classpath.
+The example also checks that these libraries are visible when used on the Module Path (JPMS), by including a module-info.java file.
+This project is part of the integration tests for a Log4j release.
+
+To build the project, and with that run all validations, run:
+
+[source,shell]
+----
+./gradlew :log4j-samples-gradle-metadata:build
+----
+
+in the samples repository root.
diff --git a/log4j-samples-gradle-metadata/build.gradle.kts b/log4j-samples-gradle-metadata/build.gradle.kts
@@ -0,0 +1,76 @@
+/*
+ * 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.
+ */
+plugins {
+    id("application")
+}
+
+val log4jVersion = providers.gradleProperty("log4j.version").getOrElse("2.+")
+
+application {
+    mainModule = "org.example.log4j.metadata"
+    mainClass = "org.example.App" // see: src/main/java/org/example/App.java
+}
+
+dependencies {
+    implementation("org.apache.logging.log4j:log4j-api:$log4jVersion")
+}
+
+tasks.withType<JavaCompile>().configureEach {
+    options.compilerArgs.add("-Werror") // treat all warnings as errors
+    options.compilerArgs.add("-Xlint:all") // includes 'classfile' check
+}
+
+// Check the classpaths
+val expectedRuntimeClasspath = listOf(
+    "log4j-api"
+)
+val expectedCompileClasspath = listOf(
+    "biz.aQute.bnd.annotation",
+    "error_prone_annotations",
+    "jspecify",
+    "jsr305",
+    "log4j-api",
+    "org.osgi.annotation.bundle",
+    "org.osgi.annotation.versioning",
+    "org.osgi.resource",
+    "org.osgi.service.serviceloader",
+    "spotbugs-annotations"
+)
+
+tasks.register("assertRuntimeClasspath") {
+    inputs.files(configurations.runtimeClasspath)
+    doLast {
+        val actual = inputs.files.map { it.name.replace(Regex("-[0-9].*"), "") }
+        assert(actual.sorted() == expectedRuntimeClasspath) {
+            "Unexpected runtime classpath: $actual"
+        }
+    }
+}
+tasks.register("assertCompileClasspath") {
+    inputs.files(configurations.compileClasspath)
+    doLast {
+        val actual = inputs.files.map { it.name.replace(Regex("-[0-9].*"), "") }
+        assert(actual.sorted() == expectedCompileClasspath) {
+            "Unexpected compile classpath: $actual"
+        }
+    }
+}
+
+tasks.check {
+    dependsOn(tasks.named("assertRuntimeClasspath"))
+    dependsOn(tasks.named("assertCompileClasspath"))
+}
diff --git a/log4j-samples-gradle-metadata/src/main/java/module-info.java b/log4j-samples-gradle-metadata/src/main/java/module-info.java
@@ -14,7 +14,6 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-plugins {
-    id 'com.android.application' version '8.8.2' apply false
-    id 'com.android.library' version '8.8.0' apply false
-}
+module org.example.log4j.metadata {
+    requires org.apache.logging.log4j;
+}
diff --git a/log4j-samples-gradle-metadata/src/main/java/org/example/App.java b/log4j-samples-gradle-metadata/src/main/java/org/example/App.java
@@ -0,0 +1,29 @@
+/*
+ * 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.
+ */
+package org.example;
+
+public class App {
+    org.apache.logging.log4j.message.ParameterizedMessage m; // needs errorprone
+    org.apache.logging.log4j.status.StatusData d; // needs spotbugs
+    org.apache.logging.log4j.util.SystemPropertiesPropertySource s; // needs aQute.bnd
+    org.apache.logging.log4j.util.Activator a; // needs osgi
+    org.apache.logging.log4j.spi.LoggerRegistry<?> r; // needs jspecify
+
+    public static void main(String[] args) {
+        System.out.println("Hello from: " + App.class.getModule().getName());
+    }
+}
diff --git a/settings.gradle b/settings.gradle
@@ -48,5 +48,11 @@ dependencyResolutionManagement {
         }
     }
 }
-rootProject.name = "Log4j Core Android"
+rootProject.name = 'logging-log4j-samples'
+
+// Android example
 include ':app'
+project(':app').projectDir = file('log4j-samples-android/app')
+
+// Gradle Metadata example
+include ':log4j-samples-gradle-metadata'
