How to have pod replica specific property file in Kubernetes?

user3132096 0
Viewed 24

I am containerizing spring-boot applications on kubernetes and I want to have a different application property file for each replica of POD. As I want to have different config for different pod replicas.

Any help on above would be appreciated.

kubernetes-pod kubernetes containers
1 Answers

They're not really replicas if you want a unique configuration for each pod. I think you may be looking for a StatefulSet. Quoting from the docs:

Like a Deployment, a StatefulSet manages Pods that are based on an identical container spec. Unlike a Deployment, a StatefulSet maintains a sticky identity for each of their Pods. These pods are created from the same spec, but are not interchangeable: each has a persistent identifier that it maintains across any rescheduling.

For example, given a StatefulSet like this:

apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: example
spec:
  selector:
    matchLabels:
      app: example
  serviceName: "example"
  replicas: 3
  template:
    metadata:
      labels:
        app: example
    spec:
      containers:
      - name: nginx
        image: docker.io/nginxinc/nginx-unprivileged:mainline
        ports:
        - containerPort: 80
          name: http

I end up with:

$ kubectl get pod
NAME        READY   STATUS    RESTARTS   AGE
example-0   1/1     Running   0          34s
example-1   1/1     Running   0          31s
example-2   1/1     Running   0          28s

In each pod, I can look at the value of $HOSTNAME to find my unique name, and I could use that to extract appropriate configuration from a directory path/structured file/etc.

larsks0
Related