Introduction

Use jolokia and hawtio to get MBean information etc. of Java application.

What is jolokia

A Java agent for accessing MBeans via http. Since it can be accessed via http, MBean information can be easily collected with curl or the like. The collected information will be returned in JSON.

What is hawtio

hawtio is a web console that allows you to monitor and manage Java applications. As standard, it supports Tomcat, Apache Camel, Apache ActiveMQ, etc. Other Java applications can also display MBean and JVM information acquired by JMX.

In JMX, hawtio does not communicate with the application by JMX, but http communication with the backend jolokia to collect MBean information and display it on the screen. In other words, hawtio and jolokia can be combined to access various remote Java applications via JMX.

This time, as a Java application to be monitored, I will try to run it using kafka that happened to be running on the server.

In addition, the procedure referred to the following article.

play + jolokia + hawtio

jolokia

Download jolokia

Download jolokia's Agent from the following site.

https://jolokia.org/download.html

Run jolokia

jolokia can be run standalone or embedded in a Java application.

(1) Run jolokia standalone

Execute the following command to display the process list of the Java application.

# java -jar jolokia-jvm-1.6.0-agent.jar 
3906   kafka.Kafka ../config/server.properties
4229   jolokia-jvm-1.6.0-agent.jar
1039   org.apache.zookeeper.server.quorum.QuorumPeerMain /opt/kafka/config/zookeeper.properties

The command options are as follows.

Usage: java -jar jolokia-jvm-1.6.0-agent.jar [options] <command> <pid/regexp>
where <command> is one of
    start     -- Start a Jolokia agent for the process specified
    stop      -- Stop a Jolokia agent for the process specified
    status    -- Show status of an (potentially) attached agent
    toggle    -- Toggle between start/stop (default when no command is given)
    list      -- List all attachable Java processes (default when no argument is given at all)
    encrypt   -- Encrypt a password which is given as argument or read from standard input

Next, run jolokia as follows. The last "3906" is the process ID of the Java application to be monitored. "Http://127.0.0.1:8778/jolokia/" displayed on the screen after execution will be the access destination to jolokia. The user ID and password for authentication of jolokia are "jolokia".

# java -jar jolokia-jvm-1.6.0-agent.jar --user jolokia --password jolokia start 3906
Started Jolokia for PID 3906
http://127.0.0.1:8778/jolokia/

(2) Execute jolokia by embedding it in a Java application

Add the following to your Java startup options: Change the path of "jolokia-jvm-1.6.0-agent.jar" according to your environment.

-javaagent:./jolokia-jvm-1.6.0-agent.jar=port=8778,host=localhost

Jolokia version check

Access jolokia via http and try to get the version information.

# curl http://localhost:8778/jolokia/version
{"request":{"type":"version"},"value":{"agent":"1.6.0","protocol":"7.2","config":{"listenForHttpService":"true","maxCollectionSize":"0","authIgnoreCerts":"false","agentId":"192.168.10.141-4698-5b480cf9-jvm","debug":"false","agentType":"jvm","policyLocation":"classpath:\/jolokia-access.xml","agentContext":"\/jolokia","serializeException":"false","mimeType":"text\/plain","maxDepth":"15","authMode":"basic","discoveryEnabled":"true","streaming":"true","canonicalNaming":"true","historyMaxEntries":"10","allowErrorDetails":"true","allowDnsReverseLookup":"true","realm":"jolokia","includeStackTrace":"true","maxObjects":"0","useRestrictorService":"false","debugMaxEntries":"100"},"info":{"product":"jetty","vendor":"Eclipse","version":"9.2.24.v20180105"}},"timestamp":1542198764,"status":200}[root@kafkaserver1 ~]#

Try to get metrics

Next, try accessing jolokia via http to get the metrics.

# curl http://localhost:8778/jolokia/read/java.lang:type=Memory/NonHeapMemoryUsage
{"request":{"mbean":"java.lang:type=Memory","attribute":"NonHeapMemoryUsage","type":"read"},"value":{"init":2555904,"committed":53477376,"max":-1,"used":50092648},"timestamp":1542198810,"status":200}[root@kafkaserver1 ~]#

Stop jolokia (if it was running standalone)

To stop Jolokia, execute the following command.

# java -jar jolokia-jvm-1.6.0-agent.jar stop 3906
Stopped Jolokia for PID 3906

Run hawtio

Download hawtio

Download the hawtio module from the following site. This time, I downloaded "hawtio-app-2.3.0.jar".

https://github.com/hawtio/hawtio/releases

Run hawtio

Run hawtio with the following command. "--Port 8090" specifies the port used by hawtio.

By default, 8080 is used. I changed it because it overlaps with other applications.

java -jar hawtio-app-2.3.0.jar --port 8090

hawtio: Don't cha wish your console was hawt like me!
=====================================================

Access the hawtio web console

The URL of the hawtio web console is as follows.

http://localhost:8090/hawtio

When you open it with a browser, the following screen will be displayed.

I will try to connect to jolokia immediately.

First, click the "Add connection" button. A dialog for entering jolokia connection information will be displayed. Enter it as shown on the screen.

When you click "Test Connection", the dialog for entering the user ID and password of jolokia is displayed. Enter the "jolokia" that was set when jolokia was started.