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Working with Namespace

Estimated time to read: 3 minutes

Namespaces are a native way to divide a single Kubernetes cluster into multiple virtual clusters.

  • Run the following command to list all Kubernetes API resources

    kubectl api-resources

  • Namespaces a good way of sharing a single cluster among different departments and environments. For example,

  • A single cluster might have the following Namespaces.

    • Dev
    • Test
    • QA

Creating Namespaces

  • Imperatively

  • Run the following command to create namespace called opsfulsionlabs

    kubectl create ns opsfulsionlabs

Declaratively

  • Run the following command to create namespace called opsfulsionlabs

    Namespace/ofl-namespace.yml
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    apiVersion: v1
kind: Namespace
metadata:
  name: opsfusionlabs
  labels:
    name: OpsFusionLabs
    env: dev

    kubectl apply -f ofl-namespace.yml

  • Auto Generate Namespace

    • Ns mainfest file in YML
      kubectl create namespace opsfusionlabs-yml -o yaml | tee ofl-namespace-autogenerate.yml
    • Ns mainfest file in JSON
      kubectl create namespace opsfusionlabs-json -o json | tee ofl-namespace-autogenerate.json

Inspecting Namespaces

  • Run the following command to list all namespaces

    kubectl get namespaces 

    kubectl get ns

  • Run the following command to describe namespaces

    kubectl describe ns deafult

Deleting Namespace

  • Imperatively

    • Run the following command to delete namespaces 

      kubectl delete ns <name od the namespace>

  • Declaratively

    • Run the following command to delete namespaces 

      kubectl delete -f ofl-namespace.yml

Set New Default Namespace

When you start using Namespaces, you’ll quickly realize it’s painful remembering to add the -n or --namespace flag on all kubectl commands. A better way might be to set your kubeconfig to automatically work with a particular Namespace.

  • Run the following command to change namespaces default to opsfusionlabs

    kubectl config set-context --current --namespace opsfusionlabs

  • Run the following command to list the objects in opsfusionlabs namespace

    kubectl get all

Mapping Objects in Specific Namespace

  • Imperatively

    • Run the following command to create nginx pod in opsfusionlabs namespace 

      kubectl run ofl-imp-nginx --image=ingnix:latest -n opsfusionlabs

  • Declaratively

    • Run the following command to create nginx pod in opsfusionlabs namespace 

      kubectl apply -f ofl-mapping-ns.yml
      Namespace/ofl-mapping-ns.yml
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      apiVersion: v1
kind: Pod
metadata: 
  name: ofl-ns-mapping
  labels:
    name: PodwithPort
    environment: production
    tier: front-end
  namespace: opsfusionlabs
spec:
  containers:
  - name: nginx
    image: nginx:latest
    ports:
    - containerPort: 80

Clean up

  • Run the following command to clear all deployment in cluster

    kubectl delete all --all -n opsfusionlabs