KAFKA-8131: Moved --version argument implementation from kafka-run-class.sh to CommandLineUtils to include documentation in command line help

bin/kafka-run-class.sh

@@ -238,13 +238,6 @@ if [ -z "$KAFKA_JVM_PERFORMANCE_OPTS" ]; then
   KAFKA_JVM_PERFORMANCE_OPTS="-server -XX:+UseG1GC -XX:MaxGCPauseMillis=20 -XX:InitiatingHeapOccupancyPercent=35 -XX:+ExplicitGCInvokesConcurrent -Djava.awt.headless=true"
 fi
 
-# version option
-for args in "$@" ; do
-  if [ "$args" = "--version" ]; then
-    exec $JAVA $KAFKA_HEAP_OPTS $KAFKA_JVM_PERFORMANCE_OPTS $KAFKA_GC_LOG_OPTS $KAFKA_JMX_OPTS $KAFKA_LOG4J_OPTS -cp $CLASSPATH $KAFKA_OPTS "kafka.utils.VersionInfo"
-  fi
-done
-
 while [ $# -gt 0 ]; do
   COMMAND=$1
   case $COMMAND in

core/src/main/scala/kafka/utils/CommandDefaultOptions.scala

@@ -22,5 +22,6 @@ import joptsimple.{OptionParser, OptionSet}
 abstract class CommandDefaultOptions(val args: Array[String], allowCommandOptionAbbreviation: Boolean = false) {
   val parser = new OptionParser(allowCommandOptionAbbreviation)
   val helpOpt = parser.accepts("help", "Print usage information.")
+  val versionOpt = parser.accepts("version", "Display Kafka version.")
   var options: OptionSet = _
 }

core/src/main/scala/kafka/utils/CommandLineUtils.scala

@@ -19,6 +19,7 @@
 import java.util.Properties
 
 import joptsimple.{OptionParser, OptionSet, OptionSpec}
+import org.apache.kafka.common.utils.AppInfoParser
 
 import scala.collection.Set
 
@@ -36,16 +37,27 @@ object CommandLineUtils extends Logging {
     return commandOpts.args.length == 0 || commandOpts.options.has(commandOpts.helpOpt)
   }
 
+  def isPrintVersionNeeded(commandOpts: CommandDefaultOptions): Boolean = {
+    return commandOpts.options.has(commandOpts.versionOpt)
+  }
+
   /**
     * Check and print help message if there is no options or `--help` option
-    * from command line
+    * from command line, if `--version` is specified on the command line
+    * print version information and exit.
+    * NOTE: The function name is not strictly speaking correct anymore
+    * as it also checks whether the version needs to be printed, but
+    * refactoring this would have meant changing all command line tools
+    * and unnecessarily increased the blast radius of this change.
     *
     * @param commandOpts Acceptable options for a command
     * @param message     Message to display on successful check
     */
   def printHelpAndExitIfNeeded(commandOpts: CommandDefaultOptions, message: String) = {
     if (isPrintHelpNeeded(commandOpts))
       printUsageAndDie(commandOpts.parser, message)
+    if (isPrintVersionNeeded(commandOpts))
+      printVersionAndDie()
   }
 
   /**
@@ -91,6 +103,11 @@ object CommandLineUtils extends Logging {
     Exit.exit(1, Some(message))
   }
 
+  def printVersionAndDie(): Nothing = {
+    System.out.println(VersionInfo.getVersionString)
+    Exit.exit(0)
+  }
+
   /**
    * Parse key-value pairs in the form key=value
    * value may contain equals sign

core/src/main/scala/kafka/utils/VersionInfo.scala

@@ -22,9 +22,19 @@ import org.apache.kafka.common.utils.AppInfoParser
 object VersionInfo {
 
   def main(args: Array[String]) {
-    val version = AppInfoParser.getVersion
-    val commitId = AppInfoParser.getCommitId
-    System.out.println(s"${version} (Commit:${commitId})")
+    System.out.println(getVersionString)
     System.exit(0)
   }
+
+  def getVersion: String = {
+    AppInfoParser.getVersion
+  }
+
+  def getCommit: String = {
+    AppInfoParser.getCommitId
+  }
+
+  def getVersionString: String = {
+    s"${getVersion} (Commit:${getCommit})"
+  }
 }