Namespaces

Question 1

What is a namespace

Answer 1

A mechanism for isolating groups of resources within a single cluster

Question 2

What are the four automatically generated namespaces

Answer 2

1. default
2. kube-system
3. kube-public
4. kube-node-lease

Question 3

What does the kube-system namespace for

Answer 3

Made for objects created by the Kubernetes system

Question 4

What does the kube-public namespace for

Answer 4

• reserved for cluster usage in case some resources need to be public

Question 5

What does the kube-node-lease namespace for

Answer 5

• holds Lease objects associated with each node

Question 6

What is a K8s Lease

Answer 6

• leases allow the kubelet to send heartbeats so that the control plane can detect node failure

Question 7

Explain an example of different namespaces

Answer 7

• The same cluster has different namespaces for dev and prod
• Namespaces have their own policy
• Namespaces have a quota of the nodes in a cluster

Question 8

How do resources within the same namespace refer to each other?

Answer 8

By their resource name (e.g. web-prod, db-service)

Question 9

How do resources communicate with other resources in another namespace

Answer 9

Using DNS.
service-name.namespace.svc.cluster.local

Question 10

How to list all pods in a namespace

Answer 10

$ k get pods –all-namespaces

Question 11

How to list pods in a specific namespace

Answer 11

$ k get pods –n=<namespace></namespace>

Question 12

How to create pod in a namespace

Answer 12

k create -f pod-definition.yaml –ns=dev

Question 13

How to create a namespace

Answer 13

$ k create namespace <name></name>

Question 14

How to get cluster IP, external IP, or ports about services in a namespace

Answer 14

k get svc -n=<namespace></namespace>