kubectl get namespaces

Create a resource such as a service, deployment, job, or namespace using the kubectl create command.

For example, to create a new namespace, type:

kubectl create namespace [namespace-name]

and

kubectl create -f [filename]

You can update a resource by configuring it in a text editor, using the kubectl edit command. This command is a combination of kubectl get and kubectl apply.

For example, to edit a service, type:

To display the state of any number of resources in detail, use the     kubectl describe command. By default, the output also lists uninitialized resources.

View details about a particular node:

To remove resources from a file or stdin, use the kubectl delete command.

Remove a pod using the name and type listed in pod.yaml:

Use kubectl exec to issue commands in a container or to open a shell in a container.

Receive output from a command run on the first container in a pod:

Listing resources- for listing pods, services, replication controllers, or daemon sets, you can use this command:

kubectl get

1. Create a plain list of all namespaces: 

Kubectl get namespaces

2. Create a list of pods:

Kubectl get pods

3. Create a detailed list of pods which must consist of information like node name:

Kubectl get pods -o wide 

4. Create a list of pods running on a specific node server:

kubectl get pods --field-selector=spec.nodeName=[server-name]

5. List a replication controller: 

kubectl get replicationcontroller [replication-controller-name]

6. Create a list of services and replication controllers together:

kubectl get replicationcontroller,services

kubectl describe 

It shows the details of the resource you are currently viewing. It’s mostly used to describe a pod or node and check for any errors in the events or if the resources are limited. Resources that can be described are – nodes, pods, deployments, services, replica sets, and Cronjobs. 

The following is an example showing how to describe the cronjob in a cluster:

 kubectl describe cronjob my-cron

Kubectl logs

The kubectl describe command provides the events that occur in the applications inside a pod, whereas kubectl logs offer detailed insights into Kubernetes. Understanding this difference will allow you to fix issues that occur in the Kubernetes as well as in applications too. 

$ kubectl logs cherry-chart-88d49478c-dmcfv -n charts

Kubectl exec

You can also execute a container just like the docker exec command for troubleshooting an application directly. This command proves to be useful when the logs don’t fix the problems that may be arising. While using the exec command, the end of the line must provide the shell you intend to use in the pod. 

kubectl exec -it cherry-chart-88d49478c-dmcfv -n charts -- /bin/bash
root@cherry-chart-88d49478c-dmcfv:/#

Kubectl cp 

If you wish to copy directories and files to and from containers, this command is a must, just like the Linux cp command. This command is essential for restoring backups when automation fails. 

Here’s the syntax to copy a file to the container:

kubectl cp <filename> <namespace/podname:/path/tofile> format

kubectl cp <namespace/podname:/path/tofile>

Cluster Management

Display endpoint information regarding the services and master in the cluster

2. Namespaces

Create namespace <name>

Node operations

A Node is a worker machine in Kubernetes and can either be a virtual or a physical machine, which depends on the cluster. Every Node is handled by the control plane. A Node can contain several pods, and the Kubernetes control plane handles scheduling the pods automatically across the Nodes in the cluster. Following commands can be utilised for Node Operation

Revise the taints on one or more nodes

 Listing Resources 

Kubernets resources also regarded as Kubernetes objects related to a certain namespace, you can either utilise individual kubectl get command to jot down every resource one by one, or you can jot down all the resources in a Kubernetes namespace by executing a single command. Mentioned below are the list of commands to get the resources information.

Create a plain-text list of all namespaces

Daemonsets 

A Daemonset assures that some or all  Nodes run a copy of a Pod. As nodes are incorporated to the cluster, Pods are implemented to them. As nodes are erased  from the cluster, those Pods are garbage collected. Erasing a DaemonSet will clean up the Pods it created.

List one or more daemonsets

Shortcode = ev
Kubernetes events are objects that displays what is happening within a cluster, like what decisions were implemented by the scheduler or why some pods were erased from the node. Events are the first thing to look at for application, along with infrastructure operations when something is not functioning as anticipated. Mentioned below are the kubectl commands to get the events.

List current events for all resources in the system

7. Logs

You can use Kubernets logs commands to monitor, log and debug the pods

Print the logs for a pod

Shortcode = deploy.

A Kubernetes Deployment is utilised to inform Kubernetes how to design or change instances of the pods that hold a containerized application. Deployments can enhance the number of replica pods, enable rollout of revised code in a controlled way, or roll back to an earlier deployment version if required.

List one or more deployments

12. Services and Service Accounts: 

A Kubernetes service is a logical abstraction for a deployed group of pods in a cluster (which all perform the same function) and Service accounts are used to provide an identity for pods. Pods that want to interact with the API server will authenticate with a particular service account.

Make a list of  one or more services

• kubectl expose deployment [deployment_name]