Admin: Created page with " =Intro= This article is based on the previois installation: Install Kubernetes 1.26 on Debian 11 with Flannel, the aim is to setup: *Simple cluster of two or more nginx p..."

2023-03-14T16:18:15Z

Created page with " =Intro= This article is based on the previois installation: Install Kubernetes 1.26 on Debian 11 with Flannel, the aim is to setup: *Simple cluster of two or more nginx p..."

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=Intro=
This article is based on the previois installation: [[Install Kubernetes 1.26 on Debian 11 with Flannel]], the aim is to setup:
*Simple cluster of two or more nginx pods
*Create a service on top
*Use the Configmap to create content
*Apply the new content

=Deployment=
deployment of 2 Nginx Pods (Replicas = 2)
*nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
name: frontend-deployment
labels:
app: web
tier: frontend
spec:
replicas: 2
selector:
matchLabels:
tier: frontend
template:
metadata:
labels:
app: web
tier: frontend
spec:
containers:
- image: nginx:latest
name: nginx
ports:
- containerPort: 30080
name: nginx

*Apply
kubectl apply -f nginx-deplyoment.yaml

*List
kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
frontend-deployment-6fb5bf7f54-4l2nv 1/1 Running 0 36s 10.244.2.12 vm-c1-worker-2 <none> <none>
frontend-deployment-6fb5bf7f54-mmfqb 1/1 Running 0 36s 10.244.1.10 vm-c1-worker-1 <none> <none>

=Service=
The service maps the label/app to '''web''' and associate the container port to port 80
* service.yaml

apiVersion: v1
kind: Service
metadata:
name: example-service
labels:
app: web
spec:
type: NodePort
selector:
app: web
ports:
- protocol: TCP
targetPort: 80
port: 80
nodePort: 30080

*Apply
kubectl apply -f service.yaml

*List

kubectl get service -o wide
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE SELECTOR
example-service NodePort 10.111.177.255 <none> 80:30080/TCP 8s app=web

=Testing=

* Apply commands to the Pod, we want to add the hostname to the nginx welcome page

kubectl get pods -o wide
NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES
'''frontend-deployment-6fb5bf7f54-nq2bl''' 1/1 Running 0 36s 10.244.2.12 vm-c1-worker-2 <none> <none>
'''frontend-deployment-6fb5bf7f54-zj44m''' 1/1 Running 0 36s 10.244.1.10 vm-c1-worker-1 <none> <none>

==Run commands inside of the pod==

*Get the hostname
kubectl exec frontend-deployment-6fb5bf7f54-nq2bl -- hostname

*Replace the message on the first Pod:
export khost=frontend-deployment-6fb5bf7f54-nq2bl
kubectl exec '''$khost''' -- \
sed -ir "s/Welcome to nginx/Welcome to nginx on $HOSTNAME/gi" /usr/share/nginx/html/index.html

*Replace the message on the second Pod:
export khost=frontend-deployment-6fb5bf7f54-zj44m
kubectl exec '''$khost''' -- \
sed -ir "s/Welcome to nginx/Welcome to nginx on $HOSTNAME/gi" /usr/share/nginx/html/index.html

*Use curl to alternate between the pods
curl -v --silent 10.111.177.255 2>&1 | grep '<title>'

=Get own content into the Nginx Pods=
==Configmap==
Get content to the cluster, create a simple index.html and add it to a configmap
kubectl create configmap index.html --from-file index.html

kubectl get configmaps
NAME DATA AGE
index.html 1 5m23s

kubectl describe configmap index.html
Name: index.html
Namespace: default
Labels: <none>
Annotations: <none>

Data
====
index.html:
...
...

=Rewrite the deployment=

*Add the volumes to nginx-deployment.yaml

apiVersion: apps/v1
kind: Deployment
metadata:
name: frontend-deployment
labels:
app: web
tier: frontend
spec:
replicas: 2
selector:
matchLabels:
tier: frontend
template:
metadata:
labels:
app: web
tier: frontend
spec:
containers:
- image: nginx:latest
name: nginx
ports:
- containerPort: 30080
name: nginx
volumeMounts:
- name: htmlcontent
mountPath: "/usr/share/nginx/html/"
readOnly: true
volumes:
- name: htmlcontent
configMap:
name: index.html
items:
- key: index.html
path: index.html

kubectl apply -f nginx-deplyoment.yaml

Kubernetes simple deployment with service and configmap - Revision history

Admin: Created page with " =Intro= This article is based on the previois installation: Install Kubernetes 1.26 on Debian 11 with Flannel, the aim is to setup: *Simple cluster of two or more nginx p..."