config-map kubernetes multiple environments

Question

I am trying to deploy a Spring Boot application using configuration data from Kubernetes cluster. 

I have a simple RestController that prints a message.

    private String message = "Message not coming from Kubernetes config map";

@RequestMapping(value="/echo", method=GET)
public String printKubeConfig() {
    return message;
}

Specified the name of the config map in my application.yml

spring:
  application:
    name: echo-configmap

echo-configmap

apiVersion: v1
kind: ConfigMap
metadata:
  name: echo-configmap
data:
  application.properties: |-
    message=Hello from dev Kubernetes Configmap
  application_qa.properties: |-
    message=Hello from qa Kubernetes Configmap

My doubt was how can you specify environment specific properties in the most efficient way?

Answer 1

Deploy your application as helm chart. 

After having created a Chart with helm create, you will get a templates/ directory, in which you might place the following YAML template for your ConfigMap:

apiVersion: v1
kind: ConfigMap
metadata:
  name: {{ printf "%s-%s" .Release.Name .Chart.Name }}
  labels:
    app: {{ .Chart.Name | trunc 63 | trimSuffix "-" }}
    chart: {{ .Chart.Name }}-{{ .Chart.Version | replace "+" "_" }}
    release: {{ .Release.Name }}
    heritage: {{ .Release.Service }}
data:
  application.properties: |-
    message={{ .Values.properties.message }}

You can add a second YAML template for your Deployment object 

containers:
  - name: {{ .Chart.Name }}
    # [...]
    volumes:
      - name: property-volume
        mountPath: /etc/your-app/properties
volumes:
  - name: property-volume
    configMap:
      name: {{ printf "%s-%s" .Release.Name .Chart.Name }}

This is how the default file values.yaml looks like

replicaCount: 1
image:
  repository: your-docker-image
  tag: your-docker-tag
properties:
  message: Hello!

Next, use this Helm chart and the helm install command to deploy your application

helm install --name dev --set image.tag=latest --set replicaCount=1 path/to/chart
$ helm install --name prod --set image.tag=stable --set replicaCount=3 --set properties.message="Hello from prod" path/to/chart