Move java version checker back to its own jar (#30708)

The java version checker requires being written with java 7 APIs.
In order to use java 8 apis in other launcher utilities, this commit
moves the java version checker back to its own jar.

distribution/build.gradle

@@ -231,6 +231,7 @@ configure(subprojects.findAll { ['archives', 'packages'].contains(it.name) }) {
       from { project(':server').jar }
       from { project(':server').configurations.runtime }
       from { project(':libs:plugin-classloader').jar }
+      from { project(':distribution:tools:java-version-checker').jar }
       from { project(':distribution:tools:launchers').jar }
       into('tools/plugin-cli') {
         from { project(':distribution:tools:plugin-cli').jar }

distribution/src/bin/elasticsearch-env

@@ -63,7 +63,7 @@ if [ ! -z "$JAVA_OPTS" ]; then
 fi
 
 # check the Java version
-"$JAVA" -cp "$ES_CLASSPATH" org.elasticsearch.tools.launchers.JavaVersionChecker
+"$JAVA" -cp "$ES_CLASSPATH" org.elasticsearch.tools.java_version_checker.JavaVersionChecker
 
 export HOSTNAME=$HOSTNAME
 

distribution/src/bin/elasticsearch-env.bat

@@ -42,7 +42,7 @@ if defined JAVA_OPTS (
 )
 
 rem check the Java version
-%JAVA% -cp "%ES_CLASSPATH%" "org.elasticsearch.tools.launchers.JavaVersionChecker" || exit /b 1
+%JAVA% -cp "%ES_CLASSPATH%" "org.elasticsearch.tools.java_version_checker.JavaVersionChecker" || exit /b 1
 
 set HOSTNAME=%COMPUTERNAME%
 

distribution/tools/java-version-checker/build.gradle

@@ -0,0 +1,14 @@
+import org.elasticsearch.gradle.precommit.PrecommitTasks
+
+apply plugin: 'elasticsearch.build'
+
+targetCompatibility = JavaVersion.VERSION_1_7
+
+// java_version_checker do not depend on core so only JDK signatures should be checked
+forbiddenApisMain.signaturesURLs = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt')]
+
+test.enabled = false
+namingConventions.enabled = false
+javadoc.enabled = false
+loggerUsageCheck.enabled = false
+jarHell.enabled = false

distribution/tools/java-version-checker/src/main/java/org/elasticsearch/tools/java_version_checker/JavaVersion.java

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-package org.elasticsearch.tools.launchers;
+package org.elasticsearch.tools.java_version_checker;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -25,8 +25,8 @@ import java.util.Objects;
 
 public class JavaVersion {
 
-    static final List<Integer> CURRENT = parse(System.getProperty("java.specification.version"));
-    static final List<Integer> JAVA_8 = parse("1.8");
+    public static final List<Integer> CURRENT = parse(System.getProperty("java.specification.version"));
+    public static final List<Integer> JAVA_8 = parse("1.8");
 
     static List<Integer> parse(final String value) {
         if (!value.matches("^0*[0-9]+(\\.[0-9]+)*$")) {
@@ -41,7 +41,7 @@ public class JavaVersion {
         return version;
     }
 
-    static int majorVersion(final List<Integer> javaVersion) {
+    public static int majorVersion(final List<Integer> javaVersion) {
         Objects.requireNonNull(javaVersion);
         if (javaVersion.get(0) > 1) {
             return javaVersion.get(0);

distribution/tools/java-version-checker/src/main/java/org/elasticsearch/tools/java_version_checker/JavaVersionChecker.java

@@ -17,7 +17,7 @@
  * under the License.
  */
 
-package org.elasticsearch.tools.launchers;
+package org.elasticsearch.tools.java_version_checker;
 
 import java.util.Arrays;
 import java.util.Locale;
@@ -45,10 +45,30 @@ final class JavaVersionChecker {
                     Locale.ROOT,
                     "the minimum required Java version is 8; your Java version from [%s] does not meet this requirement",
                     System.getProperty("java.home"));
-            Launchers.errPrintln(message);
-            Launchers.exit(1);
+            errPrintln(message);
+            exit(1);
         }
-        Launchers.exit(0);
+        exit(0);
+    }
+
+    /**
+     * Prints a string and terminates the line on standard error.
+     *
+     * @param message the message to print
+     */
+    @SuppressForbidden(reason = "System#err")
+    static void errPrintln(final String message) {
+        System.err.println(message);
+    }
+
+    /**
+     * Exit the VM with the specified status.
+     *
+     * @param status the status
+     */
+    @SuppressForbidden(reason = "System#exit")
+    static void exit(final int status) {
+        System.exit(status);
     }
 
 }

distribution/tools/java-version-checker/src/main/java/org/elasticsearch/tools/java_version_checker/SuppressForbidden.java

@@ -17,17 +17,18 @@
  * under the License.
  */
 
-package org.elasticsearch.tools.launchers;
+package org.elasticsearch.tools.java_version_checker;
 
 import java.lang.annotation.ElementType;
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;
 import java.lang.annotation.Target;
+
 /**
  * Annotation to suppress forbidden-apis errors inside a whole class, a method, or a field.
  */
 @Retention(RetentionPolicy.CLASS)
 @Target({ ElementType.CONSTRUCTOR, ElementType.FIELD, ElementType.METHOD, ElementType.TYPE })
-@interface SuppressForbidden {
+public @interface SuppressForbidden {
     String reason();
 }

distribution/tools/launchers/build.gradle

@@ -22,10 +22,8 @@ import org.gradle.api.JavaVersion
 
 apply plugin: 'elasticsearch.build'
 
-sourceCompatibility = JavaVersion.VERSION_1_7
-targetCompatibility = JavaVersion.VERSION_1_7
-
 dependencies {
+    compile parent.project('java-version-checker')
     testCompile "com.carrotsearch.randomizedtesting:randomizedtesting-runner:${versions.randomizedrunner}"
     testCompile "junit:junit:${versions.junit}"
     testCompile "org.hamcrest:hamcrest-all:${versions.hamcrest}"
@@ -33,13 +31,10 @@ dependencies {
 
 archivesBaseName = 'elasticsearch-launchers'
 
-// launchers do not depend on core so only JDK signatures should be checked
-forbiddenApisMain {
-    signaturesURLs = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt')]
-}
-forbiddenApisTest {
-    signaturesURLs = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt')]
-}
+// java_version_checker do not depend on core so only JDK signatures should be checked
+List jdkSignatures = [PrecommitTasks.getResource('/forbidden/jdk-signatures.txt')]
+forbiddenApisMain.signaturesURLs = jdkSignatures
+forbiddenApisTest.signaturesURLs = jdkSignatures
 
 namingConventions {
     testClass = 'org.elasticsearch.tools.launchers.LaunchersTestCase'
@@ -48,4 +43,4 @@ namingConventions {
 
 javadoc.enabled = false
 loggerUsageCheck.enabled = false
-jarHell.enabled=false
+jarHell.enabled = false

distribution/tools/launchers/src/main/java/org/elasticsearch/tools/launchers/JvmOptionsParser.java

@@ -38,6 +38,8 @@ import java.util.TreeMap;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 
+import org.elasticsearch.tools.java_version_checker.JavaVersion;
+
 /**
  * Parses JVM options from a file and prints a single line with all JVM options to standard output.
  */

distribution/tools/launchers/src/main/java/org/elasticsearch/tools/launchers/Launchers.java

@@ -19,6 +19,8 @@
 
 package org.elasticsearch.tools.launchers;
 
+import org.elasticsearch.tools.java_version_checker.SuppressForbidden;
+
 /**
  * Utility methods for launchers.
  */

settings.gradle

@@ -28,6 +28,7 @@ List projects = [
   'distribution:bwc:staged-minor-snapshot',
   'distribution:bwc:next-bugfix-snapshot',
   'distribution:bwc:maintenance-bugfix-snapshot',
+  'distribution:tools:java-version-checker',
   'distribution:tools:launchers',
   'distribution:tools:plugin-cli',
   'server',