Kubectl commands

With the rise of containers, nothing has changed, and popular container orchestration solutions like Kubernetes provide a command line interface (CLI). The command line tool used to manage Kubernetes clusters is called Kubectl. The Kubernetes Cluster can be managed through Kubectl. When the setup is complete, it is one of the essential elements of Kubernetes, and it runs on any workstation. To communicate with Kubernetes objects and the cluster, use Kubectl commands. Kubectl views, manages and controls the cluster via the Kubernetes API interface.

Kubectl commands - Table of Content

What is Kubectl?

The command line tool designed specifically for Kubernetes, kubectl, enables the communication between and management of Kubernetes clusters. Kubectl is a crucial tool for establishing, managing, or deleting resources on your Kubernetes environment.

The most popular method for sending HTTP queries to the Kubernetes API is kubectl, which is used to manage resources in your cluster, run Kubernetes operations, install containerized apps, perform monitoring tasks, and read system logs.

Commands like getting, delete follow the declaration, and config in the format used by kubectl (kubectl). If necessary, the resource's name is followed by the resources accessed (such as pods, deployments, or services) (this is optional for the kubectl syntax). It is possible to include flags that change the entire command, such as location (-f) or port (-port), as needed.

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Top Kubectl Commands

1. Cluster Management

A cluster of Kubernetes nodes is a group of nodes that run containerized applications. It enables containers to run on various devices and settings, including cloud-based, virtual, on-premises, and physical machines. 

2. Namespaces

Namespaces in Kubernetes offer a way to isolate the group of resources within a uni cluster. Resources' names must be distinct within and between namespaces, but not both. Only namespaced items (such as services, deployments,etc.) are eligible for namespace-based scoping; cluster-wide objects are not (e.g., PersistentVolumes, Nodes, StorageClass, etc.).

3. Node operations

In Kubernetes, a Node is a worker machine that can be either virtual or physical, depending on the cluster. The control plane manages each Node. The Kubernetes control plane automatically schedules the pods across the cluster's Nodes, and a Node may contain several pods.

4. Listing Resources

You can use multiple kubectl get commands to record each resource at a time or a single command to record all the resources in a Kubernetes namespace. Kubernetes resources are also known as Kubernetes objects associated with a specific namespace.

5. Daemonsets 

A Daemon set guarantees that one or more Nodes are running copies of a Pod. Pods are applied to nodes as they are added to the cluster. Those Pods are trash collected as nodes are removed from the cluster. A DaemonSet's produced Pods will be removed if it is erased.

6. Events

Events in Kubernetes show what happens within a cluster, such as the scheduler's decisions and why some pods were removed from a node. When something is not working as expected, events and infrastructure processes are the first to be examined for application.

7. Logs

The kubectl logs command can be used to access the logs produced by containers utilizing the stderr and stdout ports. Kubernetes provides log drivers for each container runtime that can automatically find and read these log files.

8. Deployments

To instruct Kubernetes on how to create or modify instances of the pods that house a containerized application, one uses a Kubernetes Deployment. Deployments can increase the number of replica pods, enable the controlled distribution of updated code, or, if necessary, roll back to a previous deployment version.

9. Replication Controllers

One of Kubernetes' core components, the Replication Controller, is in charge of managing the lifecycle of pods. It is in charge of ensuring that the predetermined number of pod replicas are active at all times.

10. ReplicaSets

For a particular workload, a stable set of running pods is always guaranteed by a ReplicaSet (RS), a Kubernetes object. The ReplicaSet parameter specifies the minimum number of identical pods necessary, and if a pod fails or is removed, new pods are created to compensate for the loss.

11. Secrets

A token, essential, or password are examples of sensitive data found in a Kubernetes Secret. Alternatively, such information might be included in a picture or a Pod specification. Both system-generated and user-built Secrets are available.

12. Services and Service Accounts

A deployed group of pods in a cluster carrying out the same task is referred to as a Kubernetes service, and pods are given identities using service accounts. Pods will authenticate with a specific service account to communicate with the API server.

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Kubectl concept

The control plane is the system that keeps a list of all Kubernetes objects. It continuously manages object states, reacting to cluster changes, and strives to align system objects' actual states with the desired states. The control plane comprises three main parts, the Kube-API server, Kube-controller-manager, and Kube-scheduler. These can all be replicated across several controller nodes for high availability, or they can run on a single controller node.

The controller nodes oversee the devices known as cluster nodes, which run containers. The primary and most significant controller in Kubernetes is the Kubelet. It is in charge of powering the container execution layer, which is usually Docker.

Pods are one of the fundamental ideas of Kubernetes because they are the primary building block developers work with. The previous ideas concern internal architecture and infrastructure.

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Conclusion

This list is an excellent start if you want to administer Kubernetes. These commands range in difficulty, are simple to use and have different levels of capability. It should have covered a wide range of Kubernetes components and provided some quick administration advice using kubectl. Regardless of ability level, all team members should pay attention to these directives because they are pretty strong.

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A command-line program called Kubectl is used to issue commands to Kubernetes clusters. It accomplishes this by establishing an authentication with your cluster's Controller Node and using API calls to carry out various administration tasks.

To create a Kubernetes resource directly from the command line, use the Kubectl create command. This usage is imperative. To create a new resource instance, you may alternatively use kubectl create against a manifest file.

The get pods -of broad command shows additional information and a list of all pods in the current namespace. Any extra details will be presented in straightforward English along with the findings. The Node's name is stored in pods.

If you don't specify a container name using the —container flag, kubectl debug will generate one for you automatically. Kubectl debug defaults to attaching to the new container when the -I parameter is used.

Running the kubectl cluster-info command will allow you to verify that kubectl is installed and configured correctly. Checking the nodes is another way to confirm the cluster. Run the following commands to receive comprehensive information on each Node: describe Node with kubectl.