Answer by blacktide for Best practices for storing passwords when using Spring Boot

You should use environment variables in your application.properties file for this:

spring.datasource.username=${SPRING_DATASOURCE_USERNAME}spring.datasource.password=${SPRING_DATASOURCE_PASSWORD}

Or with a default value (for development):

spring.datasource.username=${SPRING_DATASOURCE_USERNAME:admin}spring.datasource.password=${SPRING_DATASOURCE_PASSWORD:admin}

Then you can add a Kubernetes Secret to your namespace:

apiVersion: v1kind: Secretmetadata:  name: mysecret  namespace: mynamespacedata:  SPRING_DATASOURCE_PASSWORD: YWRtaW4=  SPRING_DATASOURCE_USERNAME: YWRtaW4=

And assign it to your Deployment:

apiVersion: apps/v1kind: Deploymentmetadata:  name: mydeploymentspec:  # omitted...      containers:      - name: mycontainer        envFrom:        - secretRef:            name: mysecret        - configMapRef:            name: myconfigmap  # omitted...

Another alternative would be to store the entire application.properties file in your Secret or ConfigMap and mount it into your container as a file.

Both scenarios are explained in further detail here:https://developers.redhat.com/blog/2017/10/03/configuring-spring-boot-kubernetes-configmap