Kubernetes pod level configuration externalization in spring boot app

If you want to run 4 different pods with different configurations, you have to deploy the 4 different deployments in kubernetes.

You can create the different configmap as per need storing the whole Application.yaml file or environment variables and inject it to different deployments.

how to store whole application.yaml inside config map

apiVersion: v1kind: ConfigMapmetadata:  name: yaml-region-firstdata:  application.yaml: |-    data: test,    region: first-region

the same way you can create the config map with the second deployment.

 apiVersion: v1    kind: ConfigMap    metadata:      name: yaml-region-second    data:      application.yaml: |-        data: test,        region: second-region

you can inject this configmap to each deployment

example :

apiVersion: apps/v1kind: Deploymentmetadata:  labels:    app: hello-app  name: hello-app  namespace: defaultspec:  progressDeadlineSeconds: 600  replicas: 1  revisionHistoryLimit: 10  selector:    matchLabels:      app: hello-app  strategy:    rollingUpdate:      maxSurge: 25%      maxUnavailable: 25%    type: RollingUpdate  template:    metadata:      creationTimestamp: null      labels:        app: hello-app    spec:      containers:      - name: nginx        image: nginx        imagePullPolicy: IfNotPresent        volumeMounts:          - mountPath: /etc/nginx/app.yaml            name: yaml-file            readOnly: true      volumes:      - configMap:          name: yaml-region-second          optional: false        name: yaml-file

accordingly, you can also create the helm chart.

If you just to pass the single environment instead of storing the whole file inside the configmap you can directly add value to the deployment.

Example :

apiVersion: v1kind: Podmetadata:  name: print-greetingspec:  containers:  - name: env-print-demo    image: bash    env:    - name: REGION      value: "one"    - name: HONORIFIC      value: "The Most Honorable"    - name: NAME      value: "Kubernetes"    command: ["echo"]    args: ["$(GREETING) $(HONORIFIC) $(NAME)"]

https://kubernetes.io/docs/tasks/inject-data-application/define-environment-variable-container/

for each deployment, your environment will be different and in helm, you can dynamically also update or overwrite it using CLI command.