refactor: detect java version (#40)

* refactor: detect java version

* style: remove format changes

* chore: add default if toolchain unset

Author: aaron-steinfeld

.gitignore

@@ -5,3 +5,4 @@
 build
 
 .idea
+.DS_Store

hypertrace-gradle-docker-java-application-plugin/CHANGELOG.md

@@ -54,4 +54,4 @@
 ## [0.9.9]
 
 - Fix bug introduced in 0.9.8 preventing startup. Docker laying improvements not yet working, so
-  currently equivalent to 0.9.4
+  currently equivalent to 0.9.4

hypertrace-gradle-docker-java-application-plugin/README.md

@@ -14,7 +14,8 @@ default behavior of `com.bmuschko.docker-java-application` for identifying main
 An application can define multiple variants which allow specifying different base images to use.
 
 - `javaVersion`
-    - JavaVersion 
+    - JavaVersion
+    - Defaults to the toolchain version from the java plugin
 - `baseImage`
     - String
     - Defaults to hypertrace/java:JavaMajorVersion
@@ -121,4 +122,4 @@ Produces a diff of:
 +HEALTHCHECK -interval=2s --start-period=15s --timeout=2s CMD wget -qO- http://127.0.0.1:9003/health &> /dev/null || exit 1
 -ENV SERVICE_NAME=example-app
 +ENV SERVICE_NAME=example-app MY_VAR=foo
-```
+```

hypertrace-gradle-docker-java-application-plugin/build.gradle.kts

@@ -4,8 +4,8 @@ plugins {
 }
 
 java {
-  targetCompatibility = JavaVersion.VERSION_1_8
-  sourceCompatibility = JavaVersion.VERSION_1_8
+  targetCompatibility = JavaVersion.VERSION_11
+  sourceCompatibility = JavaVersion.VERSION_11
 }
 
 gradlePlugin {
@@ -21,4 +21,3 @@ dependencies {
   api("com.bmuschko:gradle-docker-plugin:7.4.0")
   api(project(":hypertrace-gradle-docker-plugin"))
 }
-

hypertrace-gradle-docker-java-application-plugin/src/main/java/org/hypertrace/gradle/docker/HypertraceDockerJavaApplicationPlugin.java

@@ -63,9 +63,14 @@ public void apply(Project target) {
   }
 
   private void addApplicationExtension(Project project) {
-    this.getHypertraceDockerExtension(project)
-        .getExtensions()
-        .create(EXTENSION_NAME, HypertraceDockerJavaApplication.class, project.getName());
+    HypertraceDockerJavaApplication extension =
+        this.getHypertraceDockerExtension(project)
+            .getExtensions()
+            .create(EXTENSION_NAME, HypertraceDockerJavaApplication.class, project.getName());
+
+    extension.javaVersion.convention(
+        getJavaExtension(project).getToolchain().getLanguageVersion().map(JavaVersion::toVersion)
+            .orElse(JavaVersion.VERSION_11));
   }
 
   private void updateDefaultJvmArgs(Project project, HypertraceDockerJavaApplication javaApplication) {
@@ -233,11 +238,14 @@ private Configuration getRuntimeClasspath(Project project) {
   }
 
   private SourceSetOutput mainSourceSetOutput(Project project) {
-    return project.getExtensions()
-                  .getByType(JavaPluginExtension.class)
-                  .getSourceSets()
-                  .getByName(SourceSet.MAIN_SOURCE_SET_NAME)
-                  .getOutput();
+    return getJavaExtension(project)
+        .getSourceSets()
+        .getByName(SourceSet.MAIN_SOURCE_SET_NAME)
+        .getOutput();
+  }
+
+  private JavaPluginExtension getJavaExtension(Project project) {
+    return project.getExtensions().getByType(JavaPluginExtension.class);
   }
 
   private Provider<File> provideIfDirectoryExists(Provider<Directory> directoryProvider) {

hypertrace-gradle-docker-plugin/build.gradle.kts

@@ -4,8 +4,8 @@ plugins {
 }
 
 java {
-  targetCompatibility = JavaVersion.VERSION_1_8
-  sourceCompatibility = JavaVersion.VERSION_1_8
+  targetCompatibility = JavaVersion.VERSION_11
+  sourceCompatibility = JavaVersion.VERSION_11
 }
 
 gradlePlugin {

hypertrace-gradle-docker-publish-plugin/build.gradle.kts

@@ -4,8 +4,8 @@ plugins {
 }
 
 java {
-  targetCompatibility = JavaVersion.VERSION_1_8
-  sourceCompatibility = JavaVersion.VERSION_1_8
+  targetCompatibility = JavaVersion.VERSION_11
+  sourceCompatibility = JavaVersion.VERSION_11
 }
 
 gradlePlugin {