ConfigMaps

ConfigMaps allow you to decouple configuration artifacts from image content to keep containerized applications portable. They store non-confidential data in key-value pairs and can be consumed by pods as environment variables, command-line arguments, or configuration files.

ConfigMaps provide:

• Configuration Management: Store application configuration separately from code
• Environment Flexibility: Use different configurations for different environments
• Runtime Updates: Update configuration without rebuilding container images
• Portability: Keep applications portable across different environments

In this lab, you'll learn about ConfigMaps by creating one for our retail store's UI component and seeing how it connects to backend services.

Creating ConfigMap

Let's create a ConfigMap for our retail store's UI component. The UI needs to know where to find the backend services:

~/environment/eks-workshop/base-application/ui/configMap.yaml

apiVersion: v1
kind: ConfigMap
metadata:
  name: ui
data:
  RETAIL_UI_ENDPOINTS_CATALOG: http://catalog.catalog.svc:80
  RETAIL_UI_ENDPOINTS_CARTS: http://carts.carts.svc:80
  RETAIL_UI_ENDPOINTS_ORDERS: http://orders.orders.svc:80
  RETAIL_UI_ENDPOINTS_CHECKOUT: http://checkout.checkout.svc:80

A

kind: ConfigMap: Tells Kubernetes what type of resource to create

B

metadata.name: Unique identifier for this ConfigMap within the namespace

C

data: Key-value pairs containing the configuration data

Apply the ConfigMap configuration:

~$kubectl apply -k ~/environment/eks-workshop/modules/introduction/basics/configmaps/

Exploring ConfigMap

Now let's examine the ConfigMap we just created:

~$kubectl get configmaps -n ui

NAME               DATA   AGE

kube-root-ca.crt   1      2m51s

ui                 4      2m50s

Get detailed information about the ConfigMap:

~$kubectl describe configmap ui -n ui

Name:         ui

Namespace:    ui

Labels:       <none>

Annotations:  <none>

Data

====

RETAIL_UI_ENDPOINTS_CARTS:

----

http://carts.carts.svc:80

RETAIL_UI_ENDPOINTS_CATALOG:

----

http://catalog.catalog.svc:80

RETAIL_UI_ENDPOINTS_CHECKOUT:

----

http://checkout.checkout.svc:80

RETAIL_UI_ENDPOINTS_ORDERS:

----

http://orders.orders.svc:80

BinaryData

====

Events:  <none>

This shows:

• Data section - The key-value pairs stored in the ConfigMap
• Labels - Metadata tags for organization
• Annotations - Additional metadata

Using ConfigMaps in Pods

Now let's create a pod that uses our ConfigMap. We'll update our UI pod to use the configuration:

~/environment/eks-workshop/modules/introduction/basics/configmaps/ui-pod-with-config.yaml

apiVersion: v1
kind: Pod
metadata:
  name: ui-pod
  namespace: ui
  labels:
    app.kubernetes.io/name: ui
    app.kubernetes.io/component: service
    app.kubernetes.io/created-by: eks-workshop
spec:
  containers:
  - name: ui
    image: public.ecr.aws/aws-containers/retail-store-sample-ui:0.4.0
    ports:
    - containerPort: 8080
    envFrom:
    - configMapRef:
        name: ui
    resources:
      requests:
        memory: "128Mi"
        cpu: "100m"
      limits:
        memory: "256Mi"
        cpu: "200m"

A

envFrom.configMapRef: Loads all key-value pairs from the ConfigMap as environment variables

Apply the updated pod configuration:

~$kubectl apply -f ~/environment/eks-workshop/modules/introduction/basics/configmaps/ui-pod-with-config.yaml

Testing the Configuration

Let's verify that our pod can now access the configuration:

~$kubectl exec -n ui ui-pod -- env | grep RETAIL_UI_ENDPOINTS_CATALOG

RETAIL_UI_ENDPOINTS_CATALOG=http://catalog.catalog.svc:80

You can also see all the ConfigMap environment variables:

~$kubectl exec -n ui ui-pod -- env | grep RETAIL_UI

RETAIL_UI_ENDPOINTS_CATALOG=http://catalog.catalog.svc:80

RETAIL_UI_ENDPOINTS_CARTS=http://carts.carts.svc:80

RETAIL_UI_ENDPOINTS_ORDERS=http://orders.orders.svc:80

RETAIL_UI_ENDPOINTS_CHECKOUT=http://checkout.checkout.svc:80

Key Points to Remember

• ConfigMaps store non-confidential configuration data
• They decouple configuration from container images
• Can be consumed as environment variables or mounted as files
• Allow the same image to work across different environments
• Have a 1MB size limit per ConfigMap