I'm trying to use exec probes for readiness and liveness in GKE. This is because it is part of Kubernetes' recommended way to do health checks on gRPC back ends. However when I put the exec probe config into my deployment yaml and apply it, it doesn't take effect in GCP. This is my container yaml:
- name: rev79-uac-sandbox
image: gcr.io/rev79-232812/uac:latest
imagePullPolicy: Always
ports:
- containerPort: 3011
readinessProbe:
exec:
command: ["bin/grpc_health_probe", "-addr=:3011"]
initialDelaySeconds: 5
livenessProbe:
exec:
command: ["bin/grpc_health_probe", "-addr=:3011"]
initialDelaySeconds: 10But still the health checks fail and when I look at the health check configuration in the GCP console I see a plain HTTP health check directed at '/'
When I edit a health check in GCP console there doesn't seem to be any way to choose an exec type. Also I can't see any mention of liveness checks as contrasted to readiness checks even though these are separate Kubernetes things.
Does Google cloud support using exec for health checks? If so, how do I do it? If not, how can I health check a gRPC server?
Both answers from Vasily Angapov and Suresh Vishnoi should in theory work, however in practice they don't (at least in my practice).
So my solution was to start another server on my backend container - an HTTP server that simply has the job of executing the health check whenever it gets a request and returning a 200 status if it passes and a 503 if it fails.
I also had to open a second port on my container for that server to listen on.
The server has to implement the grpc probe protocol as indicated here as indicated in this article
Exec probes work in GKE just the same way they work everywhere. You can view liveness probe result in "kubectl describe pod". Or you can simply log in into pod, execute command and see its return code.
TCP probes are useful when we are using gRPC Services rather than using HTTP probes.
- containerPort: 3011
readinessProbe:
tcpSocket:
port: 3011
initialDelaySeconds: 5
periodSeconds: 10
livenessProbe:
tcpSocket:
port: 3011
initialDelaySeconds: 15
periodSeconds: 20the kubelet will attempt to open a socket to your container on the specified port. If it can establish a connection, the container is considered healthy, if it can’t it is considered a failure define-a-tcp-liveness-probe