Namespaces are a simple way to group objects in a Kubernetes cluster. It is useful to reduce the clutter when working with the Kubernetes commands but is also the basis for a number of security mechanisms.
You can see the namespaces in your cluster using:
kubectl get namespaces
Which will usually result in something like this:
NAME STATUS AGE
default Active 88d
kube-public Active 88d
kube-system Active 88d
kube-public and kube-system are namespaces used by Kubernetes specific services and controllers. You can see the pods running in a different namespace by using:
kubectl get pods -n kube-system
Most demo configurations have been applied to the default namespace so far. The configuration in other_namespace_service.yaml creates an nginx with a service inside another namespace. Apply it using
kubectl apply -f other_namespace_service.yaml
To see the pods and the service use:
kubectl -n other get pods
kubectl -n other get services
To open the respective service in your browser use:
minikube service -n other nginx
Experiment
Log into the diagnose container in the default namespace and try to access the nginx service in the "other" namespace. When inside the diagnose container you can use:
curl nginx.other