设置监听关闭端口优雅关闭tomcat

2023-06-28

阅读 ranger 代码内置 web server的部分, 启动webserver的时候设置了两个port, 并且标记其中一个为shutdownPort, 觉得有点奇怪.

咨询了chatgpt, 原来tomcat还支持优雅关闭, 提前设置好监听关闭命令的端口, 约定好监听命令, 然后就可以通过发送命令到指定端口优雅关闭了.

package org.apache.ranger.server.tomcat;

public class EmbeddedServer {

    public static int DEFAULT_SHUTDOWN_PORT = 6185;
    public static String DEFAULT_SHUTDOWN_COMMAND = "SHUTDOWN";

    public void start() {

        final Tomcat server = new Tomcat();
        String servername = EmbeddedServerUtil.getConfig("servername");
        String hostName = EmbeddedServerUtil.getConfig("ranger.service.host");
        int serverPort = EmbeddedServerUtil.getIntConfig("ranger.service.http.port", 6181);
        int shutdownPort = EmbeddedServerUtil.getIntConfig("ranger.service.shutdown.port", DEFAULT_SHUTDOWN_PORT);
        String shutdownCommand = EmbeddedServerUtil.getConfig("ranger.service.shutdown.command", DEFAULT_SHUTDOWN_COMMAND);

        server.setHostname(hostName);
        server.setPort(serverPort);
        server.getServer().setPort(shutdownPort);
        server.getServer().setShutdown(shutdownCommand);

        ...
    }
}

ranger里同时提供了用于优雅关闭tomcat的代码, 看起来就是启动一个socket连接到tomcat的shutdownPort, 然后发送shutdown命令即可.

发送命令到端口, 竟然是用print方法.

package org.apache.ranger.server.tomcat;

import java.io.PrintWriter;
import java.net.Socket;

public class StopEmbeddedServer extends EmbeddedServer {

    private static final String SHUTDOWN_HOSTNAME = "localhost";
    
    public static void main(String[] args) {
        new StopEmbeddedServer(args).stop();
    }

    public StopEmbeddedServer(String[] args) {
        super(args);
    }
    
    public void stop() {
        
        try {

            int shutdownPort = EmbeddedServerUtil.getIntConfig("ranger.service.shutdown.port", DEFAULT_SHUTDOWN_PORT );
            String shutdownCommand = EmbeddedServerUtil.getConfig("ranger.service.shutdown.command", DEFAULT_SHUTDOWN_COMMAND );

            Socket sock = new Socket(SHUTDOWN_HOSTNAME,shutdownPort);
            
            PrintWriter out = new PrintWriter(sock.getOutputStream(), true);
            
            out.println(shutdownCommand);
            
            out.flush();
            
            out.close();
        }
        catch(Throwable t) {
            System.err.println("Server could not be shutdown due to exception:" +  t);
            System.exit(1);
        }
    }

关闭命令脚本, 异步执行的java命令就是 org.apache.ranger.server.tomcat.StopEmbeddedServer

# /root/projects/ranger/embeddedwebserver/scripts/ranger-admin-services.sh

stop(){
    WAIT_TIME_FOR_SHUTDOWN=2
    NR_ITER_FOR_SHUTDOWN_CHECK=15
    if [ -f "$pidf" ] ; then
        pid=`cat $pidf` > /dev/null 2>&1
        echo "Getting pid from $pidf .."
    else
        pid=`ps -ef | grep java | grep -- '-Dproc_rangeradmin' | grep -v grep | awk '{ print $2 }'`
        if [ "$pid" != "" ];then
            echo "pid file($pidf) not present, taking pid from \'ps\' command.."
        else
            echo "Apache Ranger Admin Service is not running"
            return
        fi
    fi

    echo "Found Apache Ranger Admin Service with pid $pid, Stopping it..."
    nohup java ${JAVA_OPTS} -Duser=${USER} -Dhostname=${HOSTNAME} -Dlogdir=${RANGER_ADMIN_LOG_DIR} -Dcatalina.base=${XAPOLICYMGR_EWS_DIR} -cp "${XAPOLICYMGR_EWS_DIR}/webapp/WEB-INF/classes/conf:${XAPOLICYMGR_EWS_DIR}/lib/*:${RANGER_JAAS_LIB_DIR}/*:${RANGER_JAAS_CONF_DIR}:${RANGER_HADOOP_CONF_DIR}/*:$CLASSPATH" org.apache.ranger.server.tomcat.StopEmbeddedServer > ${RANGER_ADMIN_LOG_DIR}/catalina.out 2>&1
    for ((i=0; i<$NR_ITER_FOR_SHUTDOWN_CHECK; i++))
    do
        sleep $WAIT_TIME_FOR_SHUTDOWN
        if ps -p $pid > /dev/null ; then
            echo "Shutdown in progress. Will check after $WAIT_TIME_FOR_SHUTDOWN secs again.."
            continue;
        else
            break;
        fi
    done
    # if process is still around, use kill -9
    if ps -p $pid > /dev/null ; then
        echo "Initial kill failed, getting serious now..."
        kill -9 $pid
    fi
    sleep 1 #give kill -9  sometime to "kill"
    if ps -p $pid > /dev/null ; then
        echo "Wow, even kill -9 failed, giving up! Sorry.."
        exit 1

    else
        rm -rf $pidf
        echo "Apache Ranger Admin Service with pid ${pid} has been stopped."
    fi

}