History

chival d42e0e3162 Add more optional paramters to built-in component (#1748 ) * add probe to worker and webservice, add memory limit to webservice * add interacitve answer * make generate * move Probe def outside the parameter. * make all PodSpec alternative param done * add doc, gen yaml * fix docs		2021-06-03 19:13:43 +08:00
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README.md	Add more optional paramters to built-in component (#1748 )	2021-06-03 19:13:43 +08:00
app-with-probe.yaml	Add more optional paramters to built-in component (#1748 )	2021-06-03 19:13:43 +08:00

README.md

How to probe application's status

In this section, I'll illustrate by an example how to declare a probe to test if an application is alive.

Prerequisites

You can access a Kubernetes cluster(remotely or locally like kind or minikube)
You have installed KubeVela

Steps

Check application yaml

in app-with-probe.yaml, you'll see a livenessProbe field in properties, which shows how to test if a component is alive.

path is the health check path your web server is exposed and port is the port your server is listening to.

In this example, we use httpGet method to check the application. It's a common method in web service. Besides the httpGet probe method, you can also change it into exec or tcpSocket method.

Apply the application

Just apply the file in cluster.

kubectl apply -f app-with-probe.yaml

Check the status

the application in the cluster is rendered into resources like pod.

Try to describe the pod:

$ kubectl get pod
NAME                        READY   STATUS    RESTARTS   AGE
frontend-86bc89d8f5-xgrnc   1/1     Running   0          18s

$ kubectl describe pod frontend-86bc89d8f5-xgrnc
...
Liveness:     http-get http://:8080/ delay=0s timeout=1s period=10s #success=1 #failure=3
...(other infomation)

You'll see the pod is running without any errors. If this component is unusable reported by livenessProbe, it will restart automatically.