Monitoring cometd client

[inspire99]

CometD version(s) 5

Java version & vendor (use: java -version) Java 11

Question

I would like to monitor cometd client and check it's health from time to time.

Are there hooks within bayeuxclient which would help me do that ?

Ultimately want to expose metrics to Prometheus which will track the health of cometd clients.

Sometimes we have seen that some thread which receives the data messages is stuck, due to which subsequent meta connect doesn't go through. And sometimes there are errors from server which stops the client.

[sbordet]

BayeuxClient is currently not exposed for monitoring although its components can be exposed.

You can see an example of exposing BayeuxClient starting from this line:
https://github.com/cometd/cometd/blob/7.0.9/cometd-java/cometd-java-benchmark/cometd-java-benchmark-client/src/main/java/org/cometd/benchmark/client/CometDLoadClient.java#L352

Right now it exposes some isXYZ() methods related to its internal state.
You can add a TransportListener to be notified of transport events (messages sent or received).

Health tracking can be done by sending a special health message from the client to the server, and see if you get a reply from the server (but it requires the server to understand and reply to those messages).

For /meta/ messages, you can easily register a listener and be notified, for example, of /meta/connect messages and derive from there their rate, when the last was sent/received, its content, etc.

There is nothing pre-made, but depending on what exactly you need, you should be able to setup what you want.