github.com/oam-dev/kubevela@v1.9.11/docs/examples/app-with-probe/README.md (about)

     1  # How to probe application's status
     2  
     3  In this section, I'll illustrate by an example how to declare a probe to test if an application is alive.
     4  
     5  ## Prerequisites
     6  
     7  1. You can access a Kubernetes cluster(remotely or locally like `kind` or `minikube`)
     8  2. You have installed KubeVela
     9  
    10  ## Steps
    11  
    12  ### Check application yaml
    13  
    14  in [app-with-probe.yaml](./app-with-probe.yaml), you'll see a `livenessProbe` field in `properties`, which shows how to test if a component is alive.
    15  
    16  `path` is the health check path your web server is exposed and `port` is the port your server is listening to.
    17  
    18  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.
    19  
    20  ### Apply the application
    21  
    22  Just apply the file in cluster.
    23  ```shell
    24  kubectl apply -f app-with-probe.yaml
    25  ```
    26  
    27  ### Check the status
    28  
    29  the application in the cluster is rendered into resources like `pod`.
    30  
    31  Try to describe the pod:
    32  ```shell
    33  $ kubectl get pod
    34  NAME                        READY   STATUS    RESTARTS   AGE
    35  frontend-86bc89d8f5-xgrnc   1/1     Running   0          18s
    36  
    37  $ kubectl describe pod frontend-86bc89d8f5-xgrnc
    38  ...
    39  Liveness:     http-get http://:8080/ delay=0s timeout=1s period=10s #success=1 #failure=3
    40  ...(other infomation)
    41  ```
    42  You'll see the pod is running without any errors. If this component is unusable reported by livenessProbe, it will restart automatically.