Namespaces

Kubernetes supports multiple virtual clusters backed by the same physical cluster. These virtual clusters are called namespaces.

•       Namespaces are intended for use in environments with many users spread across multiple teams, or projects.

•       Namespaces provide a scope for names. Names of resources need to be unique within a namespace, but not across namespaces. Namespaces can not be nested inside one another and each Kubernetes resource can only be in one namespace.

•       Namespaces are a way to divide cluster resources between multiple users.

•       It is not necessary to use multiple namespaces just to separate slightly different resources, such as different versions of the same software: use labels to distinguish resources within the same namespace.

Create Namespace 

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kubectl create namespace demo1
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kubectl get namespace
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kubectl run nginx-pod --image=nginx --namespace=demo1
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kubectl get pods –namespace demo1
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kubectl delete pod nginx-pod --namespace demo1

KubeConfig file

•       Use kubeconfig files to organize information about clusters, users, namespaces, and authentication mechanisms. The kubectl command-line tool uses kubeconfig files to find the information it needs to choose a cluster and communicate with the API server of a cluster.

 KubeContext

•       A context element in a kubeconfig file is used to group access parameters under a convenient name. Each context has three parameters: cluster, namespace, and user. By default, the kubectl command-line tool uses parameters from the current context to communicate with the cluster.

Create a Pod in dev namespace

Assignment

Context and Namespaces

1. Create a dev ns and create a pod called poddev in dev ns

2. Create a prod ns and create a pod called podprod in prod ns

3. View all the pods from default ns

4. Create 2 context devcontext(dev env) and prodcontext(prod env) in config using command

5. Switch to dev env and list all the pods

6. Create a deployment uder dev ns and list all the deployments and pods

7. Switch to prod env and list all the pods

8. Create a deployment under prod ns and list all the deployments and pods

9, Switch back to default ns context

10 delete prodcontext and devContext