Use proper Java version for BWC builds (#29493)

Today we have JAVA_HOME for the compiler Java home and RUNTIME_JAVA_HOME
for the test Java home. However, when we compile BWC nodes and run them,
neither of these Java homes might be the version that was suitable for
that BWC node (e.g., 5.6 requires JDK 8 to compile and to run). This
commit adds support for the environment variables JAVA\d+_HOME and uses
the appropriate Java home based on the version of the node being
started. We even do this for reindex-from-old which requires JDK 7 for
these very old nodes. Note that these environment variables are not
required if not running BWC tests, and they are strictly required if
running BWC tests.

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

@@ -97,6 +97,12 @@ class BuildPlugin implements Plugin<Project> {
             String compilerJavaHome = findCompilerJavaHome()
             String runtimeJavaHome = findRuntimeJavaHome(compilerJavaHome)
             File gradleJavaHome = Jvm.current().javaHome
+
+            final Map<Integer, String> javaVersions = [:]
+            for (int version = 7; version <= Integer.parseInt(minimumCompilerVersion.majorVersion); version++) {
+                javaVersions.put(version, findJavaHome(version));
+            }
+
             String javaVendor = System.getProperty('java.vendor')
             String javaVersion = System.getProperty('java.version')
             String gradleJavaVersionDetails = "${javaVendor} ${javaVersion}" +
@@ -158,10 +164,32 @@ class BuildPlugin implements Plugin<Project> {
                 throw new GradleException(message)
             }
 
+            for (final Map.Entry<Integer, String> javaVersionEntry : javaVersions.entrySet()) {
+                final String javaHome = javaVersionEntry.getValue()
+                if (javaHome == null) {
+                    continue
+                }
+                JavaVersion javaVersionEnum = JavaVersion.toVersion(findJavaSpecificationVersion(project, javaHome))
+                final JavaVersion expectedJavaVersionEnum
+                final int version = javaVersionEntry.getKey()
+                if (version < 9) {
+                    expectedJavaVersionEnum = JavaVersion.toVersion("1." + version)
+                } else {
+                    expectedJavaVersionEnum = JavaVersion.toVersion(Integer.toString(version))
+                }
+                if (javaVersionEnum != expectedJavaVersionEnum) {
+                    final String message =
+                            "the environment variable JAVA" + version + "_HOME must be set to a JDK installation directory for Java" +
+                                    " ${expectedJavaVersionEnum} but is [${javaHome}] corresponding to [${javaVersionEnum}]"
+                    throw new GradleException(message)
+                }
+            }
+
             project.rootProject.ext.compilerJavaHome = compilerJavaHome
             project.rootProject.ext.runtimeJavaHome = runtimeJavaHome
             project.rootProject.ext.compilerJavaVersion = compilerJavaVersionEnum
             project.rootProject.ext.runtimeJavaVersion = runtimeJavaVersionEnum
+            project.rootProject.ext.javaVersions = javaVersions
             project.rootProject.ext.buildChecksDone = true
         }
 
@@ -173,6 +201,7 @@ class BuildPlugin implements Plugin<Project> {
         project.ext.runtimeJavaHome = project.rootProject.ext.runtimeJavaHome
         project.ext.compilerJavaVersion = project.rootProject.ext.compilerJavaVersion
         project.ext.runtimeJavaVersion = project.rootProject.ext.runtimeJavaVersion
+        project.ext.javaVersions = project.rootProject.ext.javaVersions
     }
 
     private static String findCompilerJavaHome() {
@@ -188,6 +217,10 @@ class BuildPlugin implements Plugin<Project> {
         return javaHome
     }
 
+    private static String findJavaHome(int version) {
+        return System.getenv('JAVA' + version + '_HOME')
+    }
+
     private static String findRuntimeJavaHome(final String compilerJavaHome) {
         assert compilerJavaHome != null
         return System.getenv('RUNTIME_JAVA_HOME') ?: compilerJavaHome

buildSrc/src/main/groovy/org/elasticsearch/gradle/test/NodeInfo.groovy

@@ -22,7 +22,9 @@ import com.sun.jna.Native
 import com.sun.jna.WString
 import org.apache.tools.ant.taskdefs.condition.Os
 import org.elasticsearch.gradle.Version
+import org.gradle.api.GradleException
 import org.gradle.api.InvalidUserDataException
+import org.gradle.api.JavaVersion
 import org.gradle.api.Project
 
 import java.nio.file.Files
@@ -162,7 +164,25 @@ class NodeInfo {
             args.add("${esScript}")
         }
 
-        env = ['JAVA_HOME': project.runtimeJavaHome]
+        final String javaHome
+        final Map<Integer, JavaVersion> javaVersions = project.javaVersions
+        if (Version.fromString(nodeVersion).before("6.2.0")) {
+            final String java8Home = javaVersions.get(8)
+            if (java8Home == null) {
+                throw new GradleException("JAVA8_HOME must be set to run BWC tests against [" + nodeVersion + "]")
+            }
+            javaHome = java8Home
+        } else if (Version.fromString(nodeVersion).onOrAfter("6.2.0") && Version.fromString(nodeVersion).before("6.3.0")) {
+            final String java9Home = javaVersions.get(9)
+            if (java9Home == null) {
+                throw new GradleException("JAVA9_HOME must be set to run BWC tests against [" + nodeVersion + "]")
+            }
+            javaHome = java9Home
+        } else {
+            javaHome = project.compilerJavaHome
+        }
+
+        env = ['JAVA_HOME':javaHome]
         args.addAll("-E", "node.portsfile=true")
         String collectedSystemProperties = config.systemProperties.collect { key, value -> "-D${key}=${value}" }.join(" ")
         String esJavaOpts = config.jvmArgs.isEmpty() ? collectedSystemProperties : collectedSystemProperties + " " + config.jvmArgs

distribution/bwc/build.gradle

@@ -144,12 +144,19 @@ subprojects {
   task buildBwcVersion(type: Exec) {
     dependsOn checkoutBwcBranch, writeBuildMetadata
     workingDir = checkoutDir
-    if (project.rootProject.ext.runtimeJavaVersion == JavaVersion.VERSION_1_8 && ["5.6", "6.0", "6.1"].contains(bwcBranch)) {
-      /*
-       * If runtime Java home is set to JDK 8 and we are building branches that are officially built with JDK 8, push this to JAVA_HOME for
-       * these builds.
-       */
-      environment('JAVA_HOME', System.getenv('RUNTIME_JAVA_HOME'))
+    if (["5.6", "6.0", "6.1"].contains(bwcBranch)) {
+      // we are building branches that are officially built with JDK 8, push JAVA8_HOME to JAVA_HOME for these builds
+      if (project.javaVersions.get(8) == null) {
+        throw new GradleException("JAVA8_HOME is required to build BWC versions for BWC branch [" + bwcBranch + "]")
+      }
+      environment('JAVA_HOME', project.javaVersions.get(8))
+    } else if ("6.2".equals(bwcBranch)) {
+      if (project.javaVersions.get(9) == null) {
+        throw new GradleException("JAVA9_HOME is required to build BWC versions for BWC branch [" + bwcBranch + "]")
+      }
+      environment('JAVA_HOME', project.javaVersions.get(9))
+    } else {
+      environment('JAVA_HOME', project.compilerJavaHome)
     }
     if (Os.isFamily(Os.FAMILY_WINDOWS)) {
       executable 'cmd'

qa/reindex-from-old/build.gradle

@@ -51,11 +51,13 @@ dependencies {
   es090 'org.elasticsearch:elasticsearch:0.90.13@zip'
 }
 
-if (project.runtimeJavaVersion >= JavaVersion.VERSION_1_9 || Os.isFamily(Os.FAMILY_WINDOWS)) {
-  /* We can't run the dependencies with Java 9 so for now we'll skip the whole
-   * thing. We can't get the pid files in windows so we skip that as well.... */
+if (Os.isFamily(Os.FAMILY_WINDOWS)) {
+  // we can't get the pid files in windows so we skip that
   integTest.enabled = false
 } else {
+  if (project.javaVersions.get(7) == null) {
+    throw new GradleException("JAVA7_HOME must be set to run reindex-from-old")
+  }
   /* Set up tasks to unzip and run the old versions of ES before running the
    * integration tests. */
   for (String version : ['2', '1', '090']) {
@@ -75,7 +77,7 @@ if (project.runtimeJavaVersion >= JavaVersion.VERSION_1_9 || Os.isFamily(Os.FAMI
       dependsOn unzip
       executable = new File(project.runtimeJavaHome, 'bin/java')
       env 'CLASSPATH', "${ -> project.configurations.oldesFixture.asPath }"
-      env 'JAVA_HOME', project.runtimeJavaHome
+      env 'JAVA_HOME', project.javaVersions.get(7)
       args 'oldes.OldElasticsearch',
            baseDir,
            unzip.temporaryDir,