How to access Spring-boot JMX remotely

Question

I know that spring automatically expose JMX beans. I was able to access it locally using VisualVM.

However on prod how I can connect to remotely to the app using it's JMX beans? Is there a default port or should I define anything in addition?

Thanks, ray.

Answer 1

By default JMX is automatically accessible locally, so running jconsole locally would detect all your local java apps without port exposure.

To access an app via JMX remotely you have to specify an RMI Registry port. The thing to know is that when connecting, JMX initializes on that port and then establishes a data connection back on a random high port, which is a huge problem if you have a firewall in the middle. ("Hey sysadmins, just open up everything, mkay?").

To force JMX to connect back on the same port as you've established, you have a couple options:

Option 1: Command line

-Dcom.sun.management.jmxremote.port=$JMX_REGISTRY_PORT 
-Dcom.sun.management.jmxremote.rmi.port=$RMI_SERVER_PORT

If you're using Spring Boot you can put this in your (appname).conf file that lives alongside your (appname).jar deployment.

Option 2: Tomcat/Tomee configuration

Configure a JmxRemoteLifecycleListener:

Maven Jar:

    <dependency>
        <groupId>org.apache.tomcat</groupId>
        <artifactId>tomcat-catalina-jmx-remote</artifactId>
        <version>8.5.9</version>
        <type>jar</type>
    </dependency>

Configure your server.xml:

<Listener className="org.apache.catalina.mbeans.JmxRemoteLifecycleListener"
      rmiRegistryPortPlatform="10001" rmiServerPortPlatform="10002" />

Option 3: configure programmatically

@Configuration
public class ConfigureRMI {

    @Value("${jmx.rmi.host:localhost}")
    private String rmiHost;

    @Value("${jmx.rmi.port:1099}")
    private Integer rmiPort;

    @Bean
    public RmiRegistryFactoryBean rmiRegistry() {
        final RmiRegistryFactoryBean rmiRegistryFactoryBean = new RmiRegistryFactoryBean();
        rmiRegistryFactoryBean.setPort(rmiPort);
        rmiRegistryFactoryBean.setAlwaysCreate(true);
        return rmiRegistryFactoryBean;
    }

    @Bean
    @DependsOn("rmiRegistry")
    public ConnectorServerFactoryBean connectorServerFactoryBean() throws Exception {
        final ConnectorServerFactoryBean connectorServerFactoryBean = new ConnectorServerFactoryBean();
        connectorServerFactoryBean.setObjectName("connector:name=rmi");
        connectorServerFactoryBean.setServiceUrl(String.format("service:jmx:rmi://%s:%s/jndi/rmi://%s:%s/jmxrmi", rmiHost, rmiPort, rmiHost, rmiPort));
        return connectorServerFactoryBean;
    }
}

The trick, you'll see, is the serviceUrl in which you specify both the jmx:rmi host/port and the jndi:rmi host/port. If you specify both, you won't get the random high "problem".