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Update Sunlife_Notes
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‎Sunlife_Notes

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@@ -1426,3 +1426,265 @@ kubectl get rs
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kubectl get po -l app=nginx-app
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----------------------------------------------------------------
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----------------------services--------------------
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An abstract way to expose an application running on a set of Pods as a network service.
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With Kubernetes you don't need to modify your application to use an unfamiliar service discovery mechanism. Kubernetes gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them
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CLUSTER IP
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ClusterIP is the default kubernetes service. This service is created inside a cluster and can only be accessed by other pods in that cluster. So basically we use this type of service when we want to expose a service to other pods within the same cluster.
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Nodeport:
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NodePort opens a specific port on your node/VM and when that port gets traffic, that traffic is forwarded directly to the service.
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There are a few limitations and hence its not advised to use NodePort
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- only one service per port
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- You can only use ports 30000-32767
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LoadBalancer:
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This is the standard way to expose service to the internet. All the traffic on the port is forwarded to the service. It's designed to assign an external IP to act as a load balancer for the service. There's no filtering, no routing. LoadBalancer uses cloud service
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Few limitations with LoadBalancer:
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- every service exposed will it's own ip address
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- It gets very expensive
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1. Deployment & NodePort service manifest file
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Deployment YAML file:
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~~~~~~~~~~~~~~~~~~~~~
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# Deployment
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# nginx-deploy.yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: nginx-deployment
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labels:
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app: nginx-app
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spec:
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replicas: 1
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selector:
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matchLabels:
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app: nginx-app
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template:
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metadata:
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labels:
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app: nginx-app
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spec:
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containers:
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- name: nginx-container
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image: nginx:1.7.9
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ports:
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- containerPort: 80
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--------------------------------------
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NodePort Service YAML file:
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~~~~~~~~~~~~~~~~~~~~~~~~~~
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# Service
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# nginx-svc-np.yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: my-service
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labels:
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app: nginx-app
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spec:
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selector:
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app: nginx-app
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type: NodePort
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ports:
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- nodePort: 31111
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port: 80
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targetPort: 80
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*******************************************************************
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2. Create and Display Deployment and NodePort
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kubectl create –f nginx-deploy.yaml
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kubectl create -f nginx-svc.yaml
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kubectl get service -l app=nginx-app
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kubectl get po -o wide
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kubectl describe svc my-service
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*******************************************************************
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3. Testing
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# To get inside the pod
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kubectl exec [POD-IP] -it /bin/sh
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# Create test HTML page
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cat <<EOF > /usr/share/nginx/html/test.html
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<!DOCTYPE html>
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<html>
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<head>
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<title>Testing..</title>
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</head>
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<body>
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<h1 style="color:rgb(90,70,250);">Hello, NodePort Service...!</h1>
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<h2>Congratulations, you passed :-) </h2>
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</body>
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</html>
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EOF
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exit
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Test using Pod IP:
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~~~~~~~~~~~~~~~~~~~~~~~
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kubectl get po -o wide
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curl http://[POD-IP]/test.html
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NodePort – Accessing using Service IP
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Test using Service IP:
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~~~~~~~~~~~~~~~~~~~~~~~~~~~
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kubectl get svc -l app=nginx-app
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curl http://[cluster-ip]/test.html
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Test using Node IP (external IP)
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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http://nodep-ip:nodePort/test.html
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note: node-ip is the external ip address of a node.
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*******************************************************************
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4. Cleanup
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kubectl delete -f nginx-deploy.yaml
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kubectl delete -f nginx-svc.yaml
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kubectl get deploy
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kubectl get svc
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kubectl get pods
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*******************************************************************
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LoadBalancer
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# 1. YAML: Deployment & Load Balancer Service
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# Deployment
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# controllers/nginx-deploy.yaml
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apiVersion: apps/v1
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kind: Deployment
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metadata:
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name: nginx-deployment
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labels:
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app: nginx-app
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spec:
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replicas: 1
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selector:
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matchLabels:
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app: nginx-app
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template:
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metadata:
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labels:
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app: nginx-app
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spec:
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containers:
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- name: nginx-container
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image: nginx:1.7.9
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ports:
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- containerPort: 80
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------------------------------------
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# Service - LoadBalancer
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#lb.yaml
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apiVersion: v1
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kind: Service
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metadata:
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name: my-service
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labels:
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app: nginx-app
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spec:
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selector:
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app: nginx-app
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type: LoadBalancer
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ports:
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- nodePort: 31000
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port: 80
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targetPort: 80
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------------------------------------------------

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