Namespace (ns)

• How to reach into another namespace's service from a pod
• http://nginx.dev.svc.cluster.local/route/
• cluster.local: default domain name of the kubernetes cluster
• svc: subdomain for service
• dev: namespace

• nginx: service name

• Deleting a namespace will delete all the objects associated with it

apiVersion: v1
kind: Namespace
metadata:
  name: dev
spec:
  finalizers:
    - kubernetes

Built-in namespaces

• Namespaces created automatically by Kubernetes

• default

• Empty at the cluster creation
• kube-node-lease
• Lease objects associated with each node
• Improves performance of the nodes heartbeats
• kube-public
• Accessible by all users, even unauthenticated users
• kube-system
• System objects

Namespace resources

• ResourceQuota restricts resource consumption on a namespace basis
• LimitRange: restricts resource consumption on a pod basis (so that one pod cannot monopolize the whole resource quota)

Forcefully delete a namespace

• Resolve issues with namespaces terminating forever status

# Force delete namespace in "terminating" state
kubectl get ns "dev" -o yaml > "ns.yaml"
kubectl replace --raw "/api/v1/namespaces/dev/finalize" -f "./ns.yaml" # remove spec.finalizers[0] (kubernetes)