Implement readiness and livenes probes for Kubernetes

[novoj]

See https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/

• liveness (aka restart needed) - Many applications running for long periods of time eventually transition to broken states, and cannot recover except by being restarted. Kubernetes provides liveness probes to detect and remedy such situations.
• readiness (aka i'm fine, but don't send me requests) - Sometimes, applications are temporarily unable to serve traffic. For example, an application might need to load large data or configuration files during startup, or depend on external services after startup. In such cases, you don't want to kill the application, but you don't want to send it requests either. A pod with containers reporting that they are not ready does not receive traffic through Kubernetes Services.