Chapter 4. Common kubectl Commands

Basic commands that apply to all k8s objects:

Namespaces

can be used to change the default namespace, manage different clusters or different users for authenticating to them
To change the namespace to abc, run: $ kubectl config set-context my-context --namespace=abc
This command just creates a context. To run it, use: $ kubectl config use-context my-context
This records the change in the kubectl config file while is usually located at $HOME/.kube/config. This file also stores information related to finding and authenticating to the cluster.

Everything is represented by a RESTful resource, called objects.
Each object has a unique HTTP endpoint scoped using namespaces.
kubectl uses these endpoints to fetch the objects
Viewing resources in the current namespace: kubectl get <resource-name>
Viewing a specific resource: kubectl get <resource-name> <object-name> Use describe instead of `get`` for more detailed information about the object
To get more info than normally displayed, use -o wide flag
To get raw JSON or YAML objects from the API server, use -o json, -o yaml.

k8s objects are represented using YAML or JSON files (each object has its own JSON/YAML file?)
used to manipulate objects on the server
To create an object described using obj.yaml: kubectl apply -f obj.yaml K8s automatically infers the type, it doesn’t need to be specified.

used to tag objects
kubectl label/annotate pods bar color=red adds the color=red label to a pod called bar.
To remove a label: kubectl label pods bar -color

To see logs for a container: kubectl logs <pod-name>

Use -c to choose a particular container
Use -f to stream logs to terminal
kubectl exec -it <pod-name> — bash provides an interactive shell within the container.