This kind of establishing a TCP connection to a pod (or pods) on the port specified in the configuration. This solution is especially useful for “non-HTTP” applications, for example Postfix mail server. Liveness probe tries to connect to pod, if no connection fails, pod (or pods) will reboot.
Situation where everything is fine:
Example situation where container port mismatch with the port define in Liveness probe configuration (like close port in real situation):
In this case, liveness probe will execute the command inside the container and check the returned status. The container is restarted when a status other than 0 is returned
Situation where everything is fine:
Example with problem:
This case is very helpful when maintaining WEB applications. Liveness prob recurring polls the endpoint responsible for restoring the health of the application. Returning a status from the 4xx and 5xx family will qualify the pod (pods) for restart.
Situation when health status endpoint return 2xx status code:
Situation when endpoint return status code 4xx or 5xx:
In this article, I would like to illustrate how individual Liveness probes work. Specific examples to use once with all side options are described in Design & Config.
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