톰캣 세션 클러스터링

아파치 1개와 두 개의 톰캣으로 로드 밸런싱을 구성하였다.
브라우저에서 새로고침을 할 때마다 각각의 WAS에서 로그가 올라오는 것을 보니 정상적으로 동작하는 것 같다.
문제는 로그인을 하자마자 바로 나타났다.
로그인 후에는 로그인 성공 페이지로 리다이렉트를 시키는데, 다른 WAS로 리다이렉트가 되니 오류가 발생했다.
두 개의 톰캣이 로그인 세션을 서로 공유하지 않아 생기는 오류였다.
그래서 두 개의 톰캣이 하나의 세션을 공유할 수 있도록 세션 클러스터링이 필요하다.

세션 클러스터링 구성 방법은 구글을 찾아 보니 많이 나오기도 했고 쉬웠다.

 

web.xml에 아래를 추가하고,

<distributable/>

server.xml에 아래를 추가한 후 약간의 설정만 해주면 된다.

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster"
                 channelSendOptions="8">

          <Manager className="org.apache.catalina.ha.session.DeltaManager"
                   expireSessionsOnShutdown="false"
                   notifyListenersOnReplication="true"/>
			
			<!-- 멀티캐스트 포트(45564) 필요에 따라 변경 -->
          <Channel className="org.apache.catalina.tribes.group.GroupChannel">
            <Membership className="org.apache.catalina.tribes.membership.McastService"
                        address="228.0.0.4"
                        port="45564"
                        frequency="500"
                        dropTime="3000"/>
			<!-- replication 메시지 수신 포트는 4000 - 4100 사이 -->
            <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
                      address="auto"
                      port="4000"
                      autoBind="100"
                      selectorTimeout="5000"
                      maxThreads="6"/>

            <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
              <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
            </Sender>
            <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
            <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor"/>
          </Channel>

          <Valve className="org.apache.catalina.ha.tcp.ReplicationValve"
                 filter=""/>
          <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>
		
          <Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer"
                    tempDir="/tmp/war-temp/"
                    deployDir="/tmp/war-deploy/"
                    watchDir="/tmp/war-listen/"
                    watchEnabled="false"/>
        
          <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
        </Cluster>

그런데 오류가 발생했다.

java.lang.ClassNotFoundException: org.apache.catalina.tribes.group.interceptors.MessageDispatch15Interceptor

구글에 검색해 보니 의외로 위 관련된 내용이 별로 없었다.
가끔 중국어로 된 내용이 있었으나 읽지 못하니 무시버렸고, 계속 검색만 했다.

점심먹고 와서 다시 검색해보고 결과가 나오지 않자, 중국어로 된 검색결과를 번역기를 통해 내용을 확인했다.

답은 쉽게 나왔다.

MessageDispatch15Interceptor가 없으니 MessageDispatchInterceptor를 사용하라는 얘기였다.

수정 후 서버를 재기동하니 다른 문제가 발생했다.
살짝 화가 났다.

MessageDispatch15Interceptor를 쓰라고 해놓고 왜 MessageDispatchInterceptor로 바꾸라고 얘기했을까?
혹시 톰캣 버전에 따라 설정방법이 다른 건 아닐까?

그래서 톰캣 사이트에 들어가서 문서를 찾았다.

 

tomcat.apache.org/tomcat-8.5-doc/cluster-howto.html

Apache Tomcat 8 (8.5.56) - Clustering/Session Replication How-To

위 설정대로 하니 잘 되었다.
설정 방법이 톰캣의 버전마다 조금씩 달랐었나 보다. 나는 8.5를 쓰고 있었고...

생각해보니 나도 나의 행동에 실망감을 감출 수 없었다.
처음부터 톰캣 사이트에 들어가서 검색해보면 되었을 것을 굳이 구글로 검색하겠다고 오전을 다 소비해버렸으니 말이다.
오늘을 조금 반성해 본다.

 

아래는 http://tomcat.apache.org/tomcat-8.5-doc/cluster-howto.html 의 내용이다.

<Cluster className="org.apache.catalina.ha.tcp.SimpleTcpCluster" channelSendOptions="8">

    <Manager className="org.apache.catalina.ha.session.DeltaManager" expireSessionsOnShutdown="false" notifyListenersOnReplication="true"/>

    <Channel className="org.apache.catalina.tribes.group.GroupChannel">
        <Membership className="org.apache.catalina.tribes.membership.McastService"
                    address="228.0.0.4"
                    port="45564"
                    frequency="500"
                    dropTime="3000"/>
        <Receiver className="org.apache.catalina.tribes.transport.nio.NioReceiver"
                  address="auto"
                  port="4000"
                  autoBind="100"
                  selectorTimeout="5000"
                  maxThreads="6"/>

        <Sender className="org.apache.catalina.tribes.transport.ReplicationTransmitter">
            <Transport className="org.apache.catalina.tribes.transport.nio.PooledParallelSender"/>
        </Sender>
        <Interceptor className="org.apache.catalina.tribes.group.interceptors.TcpFailureDetector"/>
        <Interceptor className="org.apache.catalina.tribes.group.interceptors.MessageDispatchInterceptor"/>
    </Channel>

    <Valve className="org.apache.catalina.ha.tcp.ReplicationValve" filter=""/>
    <Valve className="org.apache.catalina.ha.session.JvmRouteBinderValve"/>

    <Deployer className="org.apache.catalina.ha.deploy.FarmWarDeployer"
            tempDir="/tmp/war-temp/"
            deployDir="/tmp/war-deploy/"
            watchDir="/tmp/war-listen/"
            watchEnabled="false"/>

    <ClusterListener className="org.apache.catalina.ha.session.ClusterSessionListener"/>
</Cluster>