# Metricbeat jolokia module: "Cannot unmarshal json response" **URL:** \ **Category:** Beats\ **Tags:** metricbeat\ **Created:** [June 16, 2017, 3:55pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744 "2017-06-16T15:55:29Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![gregbk](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/gregbk/32/80289_2.png) [@gregbk](https://discuss.elastic.co/u/gregbk)\ **Post date:** [June 16, 2017, 3:55pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744/1 "2017-06-16T15:55:29Z")
Hello Beats team! I am trying the Jolokia module on 2 different jmx env. I got for both the same error message in kibana: `Cannot unmarshal json response: invalid character '\x00' looking for beginning of value` I use that docker to simulate a jmx: ```auto FROM java:8 MAINTAINER "Alexei Novikov " COPY . /usr/src/myapp WORKDIR /usr/src/myapp RUN javac Hammer.java CMD ["java", \ "-Dcom.sun.management.jmxremote", \ "-Dcom.sun.management.jmxremote.port=9010", \ # Uncomment this line when running JMX console on a different host #"-Dcom.sun.management.jmxremote.rmi.port=9010", \ "-Dcom.sun.management.jmxremote.local.only=false", \ "-Dcom.sun.management.jmxremote.authenticate=false", \ "-Dcom.sun.management.jmxremote.ssl=false", \ # Uncomment this line when running JMX console on a different host, use a name of the host where Docker is running #"-Djava.rmi.server.hostname=192.168.0.101", \ "Hammer"] EXPOSE 9010 ``` And this minimum metricbeat conf: ```auto metricbeat.modules: - module: jolokia metricsets: ["jmx"] enabled: true period: 1s hosts: ["jmx:9010"] namespace: "metrics" #path: "/jolokia/?ignoreErrors=true&canonicalNaming=true" jmx.mappings: - mbean: 'java.lang:type=Runtime' attributes: - attr: Uptime field: uptime ``` Event is send and coming to the right index `fetches.jolokia-jmx.events=30 fetches.jolokia-jmx.failures=30` but with error: `Cannot unmarshal json response: invalid character '\x00' looking for beginning of value` I am on 5.4.1 for elk+metricbeat. On a totally different jmx server in another env, I got the same error. Probably my metricbeat/(es template?) is missing something... I tried to send to logstash and directly to es: same result. Similar to [Metricbeat 5.4.0 Jolokia module](https://discuss.elastic.co/t/metricbeat-5-4-0-jolokia-module/86319) Thank you for your help & good weekend! Greg. ---
**Author:** ![andrewkroh](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/andrewkroh/32/3784_2.png) [@andrewkroh](https://discuss.elastic.co/u/andrewkroh)\ **Post date:** [June 16, 2017, 4:31pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744/2 "2017-06-16T16:31:57Z")
If I understand your setup correctly, you are trying to communicate directly to the JMX endpoint in the JVM. Metricbeat needs to communicate to the [Jolokia](https://jolokia.org/reference/html/index.html) REST endpoint. Jolokia acts as a bridge between Metricbeat and JMX and exposes a HTTP/REST/JSON interface to JMX. ---
**Author:** ![joshuaclark](https://avatars.discourse-cdn.com/v4/letter/j/5daacb/32.png) [@joshuaclark](https://discuss.elastic.co/u/joshuaclark)\ **Post date:** [June 16, 2017, 4:39pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744/3 "2017-06-16T16:39:35Z")
You need to follow the steps from this document [https://jolokia.org/reference/html/agents.html#agents-jvm](https://jolokia.org/reference/html/agents.html#agents-jvm) 3.4.1.1. Installation section. then set metricbeat to connect to the JVM host and the port you set for the Jolokia agent. You then would be able to connect to [http://host:7777/jolokia/read/java.lang:name=PS%20Scavenge,type=GarbageCollector](http://host:7777/jolokia/read/java.lang:name=PS%20Scavenge,type=GarbageCollector) etc. ---
**Author:** ![gregbk](https://sea2.discourse-cdn.com/elastic/user_avatar/discuss.elastic.co/gregbk/32/80289_2.png) [@gregbk](https://discuss.elastic.co/u/gregbk)\ **Post date:** [June 19, 2017, 1:09pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744/4 "2017-06-19T13:09:42Z")
Thanks a lot both! Yes, I had in mind that I needed to connect to jmx only while jolokia agent only can be understood by metricbeat... Here is the right setup: ```auto FROM java:8 MAINTAINER "Alexei Novikov " COPY . /usr/src/myapp WORKDIR /usr/src/myapp RUN javac Hammer.java ENV JOLOKIA_VERSION 1.3.1 RUN mkdir /opt/jolokia && wget http://central.maven.org/maven2/org/jolokia/jolokia-jvm/1.3.1/jolokia-jvm-1.3.1-agent.jar -O /opt/jolokia/jolokia.jar # Print out the version RUN java -jar /opt/jolokia/jolokia.jar --version CMD ["java", \ "-javaagent:/opt/jolokia/jolokia.jar=port=8778,host=0.0.0.0", \ "-Dcom.sun.management.jmxremote", \ "-Dcom.sun.management.jmxremote.port=9010", \ # Uncomment this line when running JMX console on a different host #"-Dcom.sun.management.jmxremote.rmi.port=9010", \ "-Dcom.sun.management.jmxremote.local.only=false", \ "-Dcom.sun.management.jmxremote.authenticate=false", \ "-Dcom.sun.management.jmxremote.ssl=false", \ # Uncomment this line when running JMX console on a different host, use a name of the host where Docker is running #"-Djava.rmi.server.hostname=192.168.0.101", \ "Hammer"] EXPOSE 9010 8778 ``` ```auto - module: jolokia metricsets: ["jmx"] enabled: true period: 1s hosts: ["jmx:8778"] namespace: "metrics" path: "/jolokia/?ignoreErrors=true&canonicalNaming=true" jmx.mappings: - mbean: 'java.lang:type=ClassLoading' attributes: - attr: LoadedClassCount field: loaded_class_count - mbean: 'java.lang:name=PS Scavenge,type=GarbageCollector' attributes: - attr: CollectionTime field: gc.collection_time - attr: CollectionCount field: gc.collection_count - mbean: 'java.lang:type=Memory' attributes: - attr: HeapMemoryUsage field: heap_memory_usage - attr: NonHeapMemoryUsage field: non_heap_memory_usage - mbean: 'java.lang:type=OperatingSystem' attributes: - attr: ProcessCpuLoad field: process_cpu_load - mbean: 'java.lang:type=Runtime' attributes: - attr: Uptime field: uptime - mbean: 'java.lang:type=Threading' attributes: - attr: ThreadCount field: thread_count ``` Thx! ---
**Author:** ![system](https://us1.discourse-cdn.com/elastic/original/3X/1/a/1ac57faf039f6b580b3f104ef42a2a89e41014de.png) [@system](https://discuss.elastic.co/u/system)\ **Post date:** [July 17, 2017, 1:09pm UTC](https://discuss.elastic.co/t/metricbeat-jolokia-module-cannot-unmarshal-json-response/89744/5 "2017-07-17T13:09:44Z")
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