Runtime Java home

Author: jasontedor

CONTRIBUTING.md

@@ -96,8 +96,9 @@ JDK 9 is required to build Elasticsearch. You must have a JDK 9 installation
 with the environment variable `JAVA_HOME` referencing the path to Java home for
 your JDK 9 installation. By default, tests use the same runtime as `JAVA_HOME`.
 However, since Elasticsearch, supports JDK 8 the build supports compiling with
-JDK 9 and testing on a JDK 8 runtime; to do this, set `JAVA_8_HOME` pointing to
-the Java home of a JDK 8 installation. 
+JDK 9 and testing on a JDK 8 runtime; to do this, set `RUNTIME_JAVA_HOME`
+pointing to the Java home of a JDK 8 installation. Note that this mechanism can
+be used to test against other JDKs as well, this is not only limited to JDK 8.
 
 Elasticsearch uses the Gradle wrapper for its build. You can execute Gradle
 using the wrapper via the `gradlew` script in the root of the repository.

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -94,7 +94,7 @@ class BuildPlugin implements Plugin<Project> {
     static void globalBuildInfo(Project project) {
         if (project.rootProject.ext.has('buildChecksDone') == false) {
             String compilerJavaHome = findCompilerJavaHome()
-            String runtimeJavaHome = findRuntimeJavaHome(project)
+            String runtimeJavaHome = findRuntimeJavaHome(compilerJavaHome)
             File gradleJavaHome = Jvm.current().javaHome
             String javaVendor = System.getProperty('java.vendor')
             String javaVersion = System.getProperty('java.version')
@@ -168,42 +168,22 @@ class BuildPlugin implements Plugin<Project> {
 
     /** Finds and enforces JAVA_HOME is set */
     private static String findCompilerJavaHome() {
-        String javaHome = System.getenv('JAVA_HOME')
-        if (javaHome == null) {
-            if (System.getProperty("idea.active") != null || System.getProperty("eclipse.launcher") != null) {
-                // intellij doesn't set JAVA_HOME, so we use the jdk gradle was run with
-                javaHome = Jvm.current().javaHome
-            } else {
-                throw new GradleException('JAVA_HOME must be set to build Elasticsearch')
-            }
-        }
-        return javaHome
+        return findJavaHome(System.getenv('JAVA_HOME'), null)
     }
 
-    private static String findRuntimeJavaHome(Project project) {
-        String java8Home = System.getenv('JAVA_8_HOME')
-        final String maybeJavaHome
-        if (java8Home == null) {
-            // if JAVA_8_HOME is not set fallback to JAVA_HOME
-            maybeJavaHome = System.getenv('JAVA_HOME')
-        } else {
-            // if JAVA_8_HOME is set it must point to a JDK 8 Java home
-            JavaVersion version = JavaVersion.toVersion(findJavaSpecificationVersion(project, java8Home))
-            if (version.majorVersion != minimumRuntimeVersion.majorVersion) {
-                throw new GradleException("if JAVA_8_HOME is set it must point to a JDK 8 Java home but was [" + java8Home + "]")
-            }
-            maybeJavaHome = java8Home
-        }
-        final String javaHome
-        if (maybeJavaHome == null) {
+    private static String findRuntimeJavaHome(final String compilerJavaHome) {
+        return findJavaHome(System.getenv('RUNTIME_JAVA_HOME'), compilerJavaHome)
+    }
+
+    private static String findJavaHome(String maybeJavaHome, String defaultJavaHome) {
+        final String javaHome = maybeJavaHome ?: defaultJavaHome
+        if (javaHome == null) {
             if (System.getProperty("idea.active") != null || System.getProperty("eclipse.launcher") != null) {
                 // IntelliJ does not set JAVA_HOME, so we use the JDK that Gradle was run with
                 javaHome = Jvm.current().javaHome
             } else {
                 assert false
             }
-        } else {
-            javaHome = maybeJavaHome
         }
         return javaHome
     }