Configuring a Deployment to Use a ConfigMap

Objective

After completing this lesson, you will be able to configure a deployment to use a ConfigMap

Configure a Deployment to Use a ConfigMap

Usage Scenario

You want to deploy an application to SAP BTP, Kyma runtime, which must be configured with environment variables. You want to store these environment variables in a ConfigMap and inject them into your application.

Task Flow

In this exercise, you will perform the following steps:

  1. Create a ConfigMap.
  2. Deploy an application with the ConfigMap and verify the result.

Prerequisites

Before you begin, ensure that the following prerequisites are met:

Task 1: Create a ConfigMap

Steps

  1. Create a new file called config-map.yaml. You can specify your first name and a greeting message:

    Code Snippet
    1234567
    apiVersion: v1
kind: ConfigMap
metadata:
  name: name-greeting
data:
    GREETING: "Hello"
    FIRSTNAME: "Kyma"

  2. Apply the ConfigMap using kubectl.

    Code Snippet
    1
    kubectl apply -f config-map.yaml

  3. Check if the ConfigMap has been created:

    Code Snippet
    1
    kubectl get configmaps

Result

If successful, the printed list contains the name-greeting ConfigMap.

Task 2: Deploy an Application with the ConfigMap

Steps

  1. Create a new file called deployment.yaml that specifies the Deployment configuration:

    YAML
    12345678910111213141516171819202122
    apiVersion: apps/v1
kind: Deployment
metadata:
  name: test-configmap
spec:
  replicas: 1
  selector:
    matchLabels:
      app: test-configmap
  template:
    metadata:
      labels:
        app: test-configmap
    spec:
      containers:
      - name: test-configmap
        image: bash
        envFrom:
        - configMapRef:
            name: name-greeting
        command: ["echo"]
        args: ["$(GREETING) $(FIRSTNAME)!"]

  2. Apply the Deployment using kubectl.

    Code Snippet
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    kubectl apply -f deployment.yaml

  3. Get the Pod name.

    Code Snippet
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    kubectl get pods -l app=test-configmap

  4. Get the output of the Pod.

    Code Snippet
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    kubectl logs <pod-name>

    Alternatively, you could also retrieve the logs using the label selector:

    Code Snippet
    1
    kubectl logs -l app=test-configmap

  5. Delete the Deployment.

    Code Snippet
    1
    kubectl delete deployment test-configmap

Result

In this exercise, you have created a ConfigMap and deployed an application that uses the ConfigMap.

Further Reading

Configure a Pod to use a ConfigMap

Learning

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