Readiness probe

💻 Tech

Services send traffic to the pods if the pod’s condition is Ready. However, if the container is running, yet the application isn’t fully available to accept incoming traffic, it may result to issues like timeouts or delays. This is where readiness probe comes in. Readiness probe allows us to specify what kind of test to perform before a pod condition becomes Ready.

Test can be in form of the following:

HTTP

readinessProbe:
   httpGet:
     path: /api/ready
     port: 8080

TCP

readinessProbe:
   tcpSocket:
     port: 3306

Exec command

readinessProbe:
   exec:
     command:
       - ./check_readiness

One example of how HTTP test is used:

apiVersion: v1
kind: Pod
...
spec:
  containers:
  - name: app
    image: app
    ports:
      - containerPort: 8080
    readinessProbe:
      httpGet:
         path: /api/ready
         port: 8080