HiveMQ Prometheus extension NoClassDefFoundError. Can't start extension

Question

I'm running the hivemq mqtt broker community edition and wanted to add the prometheus extension for monitoring.
Both come precompiled from the hivemq marketplace and the github project page.
I download both components as a zip file, unzip them and copy them into a java 11 docker container using this dockerfile:

FROM alpine:3.10  AS TOOLCHAIN
ADD https://github.com/hivemq/hivemq-community-edition/releases/download/2019.1/hivemq-ce-2019.1.zip /opt/
ADD https://www.hivemq.com/releases/extensions/hivemq-prometheus-extension-4.0.1.zip /opt/
WORKDIR /opt
RUN unzip hivemq-ce-* -d ./
RUN unzip hivemq-prometheus-extension* -d ./
RUN rm -rf hivemq-ce-*.zip
RUN rm -rf hivemq-prometheus-extension*.zip
RUN mv ./hivemq-ce-* ./hivemq

FROM openjdk:11-jdk-slim
COPY --from=TOOLCHAIN /opt/hivemq /opt/hivemq
COPY --from=TOOLCHAIN /opt/hivemq-prometheus-extension /opt/hivemq/extensions/hivemq-prometheus-extension
WORKDIR /opt/hivemq/
CMD ["chmod","755","./bin/run.sh"]
CMD ["./bin/run.sh"]

I think I got the steps from the how to's right, but when I start the container with docker build -t hive-test .; docker run -p 1883:1883 -p 9399:9399 -t hive-test I get an error.

2019-07-24 13:19:57,125 INFO  - Starting HiveMQ Community Edition Server
2019-07-24 13:19:57,127 INFO  - HiveMQ version: 2019.1
2019-07-24 13:19:57,127 INFO  - HiveMQ home directory: /opt/hivemq
2019-07-24 13:19:57,162 INFO  - Log Configuration was overridden by /opt/hivemq/conf/logback.xml
2019-07-24 13:19:57,356 INFO  - This HiveMQ ID is mwDbQ
2019-07-24 13:20:14,353 INFO  - Created user preferences directory.
2019-07-24 13:20:14,873 INFO  - Starting HiveMQ extension system.
2019-07-24 13:20:14,925 INFO  - Starting TCP listener on address 0.0.0.0 and port 1883
2019-07-24 13:20:14,998 INFO  - Started TCP Listener on address 0.0.0.0 and on port 1883
2019-07-24 13:20:14,999 INFO  - Started HiveMQ in 17877ms
2019-07-24 13:20:15,040 ERROR - Extension with id "hivemq-prometheus-extension" cannot be started because of an uncaught exception thrown by the extension. Extension will be disabled.
java.lang.NoClassDefFoundError: javax/servlet/ServletContextListener
        at org.eclipse.jetty.server.handler.ContextHandler.<clinit>(ContextHandler.java:114)
        at com.hivemq.extensions.prometheus.export.PrometheusServer.start(PrometheusServer.java:64)
        at com.hivemq.extensions.prometheus.PrometheusMainClass.extensionStart(PrometheusMainClass.java:65)
        at com.hivemq.extensions.HiveMQExtensionImpl.start(HiveMQExtensionImpl.java:133)
        at com.hivemq.extensions.HiveMQPlugins.pluginStart(HiveMQPlugins.java:209)
        at com.hivemq.extensions.loader.PluginLifecycleHandlerImpl.lambda$startPlugin$0(PluginLifecycleHandlerImpl.java:82)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
        at java.base/java.lang.Thread.run(Thread.java:834)
Caused by: java.lang.ClassNotFoundException: javax.servlet.ServletContextListener
        at java.base/java.net.URLClassLoader.findClass(URLClassLoader.java:471)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:588)
        at com.hivemq.extensions.classloader.IsolatedPluginClassloader.loadClass(IsolatedPluginClassloader.java:123)
        at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
        ... 9 common frames omitted

I also downloaded the broker and extension source code and tried to compile it by myself with maven/gradle and java 11. But that had the exact same result.

The broker runs without any errors.

Does anyone know what went wrong here?

score 0 · Accepted Answer · answered Jul 24 '19 at 15:24

Actually no dependency from the hivemq broker community edition contains ServletContextListener. I downloaded the source code from github and modified the build.gradle file.

Add the last line of the following snippet to the build.gradle file:

/* javax */
[group: 'javax.activation', name: 'activation', version: '1.1.1'],
[group: 'javax.validation', name: 'validation-api', version: '1.1.0.Final'],
[group: 'javax.annotation', name: 'javax.annotation-api', version: '1.3.2'],
[group: 'javax.servlet', name: 'javax.servlet-api', version: '4.0.1'],

After compiling the broker unzip the result and add the precompiled extension to the extension directory.

The error is gone and the extension seems to be working.

HiveMQ Prometheus extension NoClassDefFoundError. Can't start extension

1 Answers1