Choosing between TCP probe and HTTP probe for liveness and readiness in kubernetes
In my experience HTTP is chosen over TCP when you have a reverse-proxy sidecar in front of your app in the same pod, e.g. nginx. In this case, nginx will always accept TCP even when the app is not ready yet. Thus you'd want HTTP.
Otherwise:
- if this is an app server listening directly on a port
- you know it starts to listen only when fully loaded
- you don't want any additional logic inside
/health(like check db connection)
If all of the above is true - just use TCP.
TIP You don't even need to know the port number for TCP, you can use named port: https://kubernetes.io/docs/tasks/configure-pod-container/configure-liveness-readiness-startup-probes/#use-a-named-port