A ConfigMap is an API object used to store non-confidential data in key-value pairs. Pods can consume ConfigMaps as environment variables, command-line arguments, or as configuration files in a volume.
https://kubernetes.io/docs/concepts/configuration/configmap/
We can take the environment information out of the pod definition file and manage it centrally using ConfigMap. ConfigMap is used to pass configuration data in the form of key-value pairs in Kubernetes. When it pod is created inject the configMap into the pod. So the key-value pairs are available as environment variables for the application hosted inside the container in the pod.
- Create and Check ConfigMap
- Inject data into the pod from ConfigMap.
- Create NodePort Service for checking ConfigMap data in a pod.
Create ConfigMap
$ kubectl create configmap \
phonenumbers --from-literal=jay=+82-123-1456-1234 \
--from-literal=tim=+1-647-1203-1230Create ConfigMap by YAML file
apiVersion: v1
kind: ConfigMap
metadata:
name: phonenumbers
data:
jay: +82-010-5010-1020
tim: +1-647-1023-1023$ kubectl create -f phonenumbers-configmap.yaml
configmap/first-config created
$ kubectl describe configmaps phonenumbers
Name: phonenumbers
Namespace: default
Labels: <none>
Annotations: <none>
Data
====
jay:
----
+82-010-5010-1020
tim:
----
+1-647-1023-1023
Events: <none>Inject data into the pod (application) from ConfigMap.
apiVersion: v1
kind: Pod
metadata:
name: k8s-configmaps-node-pod
labels:
app: k8s-configmaps-node
spec:
containers:
- name: k8s-configmaps-node-container
image: jayjodev/k8s-node-app:latest
envFrom:
- configMapRef:
# will save in process.env
name: phonenumbers
ports:
- containerPort: 4000
protocol: TCP$ kubectl create -f k8s-configmaps-node-pod.yaml
pod/k8s-configmaps-node-pod created
$ kubectl get pods
NAME READY STATUS RESTARTS AGE
k8s-configmaps-node-pod 1/1 Running 0 12sjayjodev/k8s-node-app image is node application to check k8s Configmaps and Secrets data
Create NodePort Service for checking ConfigMap data in a pod
apiVersion: v1
kind: Service
metadata:
name: k8s-configmaps-node-nodeport-service
spec:
type: NodePort
ports:
- targetPort: 4000
port: 80
nodePort: 30001
selector:
app: k8s-configmaps-node$ kubectl create -f k8s-configmaps-node-nodeport-service.yaml
service/k8s-configmaps-node-nodeport-service created
$ kubectl get services
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
k8s-configmaps-node-nodeport-service NodePort 10.108.29.96 <none> 80:30001/TCP 40sIf you are using Minikube for testing, type, you can access the app and test in Minikube
$ minikube ssh
docker@minikube:~$ curl localhost:30001/api/configmaps/jay
+82-010-5010-1020
docker@minikube:~$ curl localhost:30001/api/configmaps/tim
+1-647-1023-1023or
Access the app and test outside of Minikube
$ minikube service --url k8s-configmaps-node-nodeport-service
🏃 Starting tunnel for service k8s-configmaps-node-nodeport-service.
|-----------|--------------------------------------|-------------|------------------------|
| NAMESPACE | NAME | TARGET PORT | URL |
|-----------|--------------------------------------|-------------|------------------------|
| default | k8s-configmaps-node-nodeport-service | | http://127.0.0.1:55532 |
|-----------|--------------------------------------|-------------|------------------------|
http://127.0.0.1:55532
❗ Because you are using a Docker driver on darwin, the terminal needs to be open to run it.at another terminal
curl http://127.0.0.1:55532/api/configmaps/jay
+82-010-5010-1020
curl http://127.0.0.1:55532/api/configmap/tim
+1-647-1023-1023# Environment
envFrom:
- configMapRef:
name: <configmap_name>
# Single Environment
env:
- name: redis
valueFrom:
configMapKeyRef:
name: <configmap_name>
key: redis
# Volume
volumes:
- name: <volume_name>
configMap:
name: <configmap_name>