Namespaces are the default way for kubernetes to separate resources. Namespaces do not share anything between them, which is important to know, and thus come in handy when you have multiple users on the same cluster, that you don't want stepping on each other's toes :)
Choose a name for your namespace, something unique so you don't clash with one of the other participants at the workshop.
$ kubectl create namespace my-namespace
namespace "my-namespace" createdYou want to target your own namespace instead of default one every time you use kubectl.
You can run a command in a specific namespace by using the -n, --namespace=''-flag.
The below commands do the same thing, because kubernetes commands will default to the default namespace:
kubectl get pods -n default
kubectl get podsIt gets tedious however to write this every time you want to select your own namespace, so it makes sense to set this as the default.
To overwrite the default namespace for your current context, run:
$ kubectl config set-context $(kubectl config current-context) --namespace=my-namespace
Context "<your current context>" modified.Or perform the same step with two individual commands:
[student-1@kamran-jumpbox ~]$ kubectl config current-context
gke_praqma-education_europe-north1-a_kamran-test-cluster-0617
[student-1@kamran-jumpbox ~]$ kubectl config set-context gke_praqma-education_europe-north1-a_kamran-test-cluster-0617 --namespace=student-1
Context "gke_praqma-education_europe-north1-a_kamran-test-cluster-0617" modified.
[student-1@kamran-jumpbox ~]$
You can verify that you've updated your current context by running:
kubectl config get-contexts[student-1@kamran-jumpbox ~]$ kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* gke_praqma-education_europe-north1-a_kamran-test-cluster-0617 gke_praqma-education_europe-north1-a_kamran-test-cluster-0617 gke_praqma-education_europe-north1-a_kamran-test-cluster-0617 student-1
[student-1@kamran-jumpbox ~]$
Notice that the namespace column has the value of <my-namespace>.
Most errors you will get throughout the rest of the workshop will 99% be due to deploying into a namespace, where someone's already done the exercise before you; always ensure you're using your newly created namespace!
Namespaces are quite powerful. On a user level, it is also possible to limit namespaces and resources by users but this is a bit too involved for your first experience with Kubernetes. Therefore, please be aware that other people's namespaces are off limits for this workshop; even if you do have access ;)
Kubernetes clusters come with a namespace called default, which in this case might contain some pods deployed previously by Praqma,
and usually one called kube-system which will contain some of the kubernetes services running in the cluster.
You might see later that the namespace is specified directly in the yaml files describing the resources.
This makes it possible to have the resource created in the specific namespace without specifying the -n flag on creation.