HTTP Requests

An HTTP request is a mechanism that lets you create a liveness probe. You can expose an HTTP endpoint by implementing any lightweight HTTP server within the container. A probe performs an HTTP GET request against this endpoint at the container’s IP to check if the service is alive. If the endpoint returns a success code, kubelet considers the container alive and healthy. If not, the kubelet terminates and restarts this container.

Commands

You can configure a command probe to get kubelet to execute the cat /tmp/healthy command in a certain container. If the command succeeds, kubelet considers the container alive and healthy. If not, it shuts down the container and restarts it.

TCP Connections

A TCP socket probe tells Kubernetes to open a TCP connection on a specified port on the container. If it succeeds, Kubernetes considers the container healthy. You should use TCP probes for gRPC and FTP services that already include the TCP protocol infrastructure.