Kubectl Cheat Sheet

Kubectl is the CLI tool for Kubernetes that allows you to interact with your clusters, create, manage, edit, and delete resources with ease. It communicates with the Kubernetes API server so you can monitor and control your applications.

Kubectl operates by sending commands to the Kubernetes API server, which then carries out the requested operations within the cluster. When you execute a kubectl command, such as deploying an application or retrieving the status of resources, kubectl communicates with the API server over HTTP, transmitting your instructions. The API server processes these requests, updates the cluster's state in etcd (a distributed key-value store), and directs other components, like the scheduler or controller manager, to perform necessary actions to achieve the desired state. This interaction allows you to efficiently manage and monitor your Kubernetes resources from the command line. ​

In earlier versions of Kubernetes, kubectl utilized generators to create resource configurations based on specific inputs. These generators allowed users to specify the type of resource to create, such as a Pod, Deployment, or Job, by using the --generator flag. For example, kubectl run nginx --image=nginx --generator=run-pod/v1 would create a Pod resource. This approach enabled users to script and automate resource creation with predictable outcomes. However, it's important to note that the --generator flag was deprecated in Kubernetes v1.12 and removed in v1.18. As of v1.18, kubectl run is simplified to create only Pods, and the use of generators has been replaced by more explicit and declarative commands like kubectl create and kubectl apply

Now, let’s start:

Kubectl provides optional flags that enhance command output and resource management. For example:

Output Formats:

JSON Output:

You can use the -o=json flag to format command output as JSON.

kubectl get pods -o=json

YAML Output:

You can use the -o=yaml flag to format command output as YAML.

kubectl get pods -o=yaml

Wide Output:

The -o=wide option provides detailed plain-text output (e.g., it displays the node name for pods).

kubectl get pods -o=wide

For more tailored outputs, kubectl offers the --custom-columns flag, allowing you to define specific columns to display. 

For example, to list pods with their names and the nodes they're running on:

kubectl get pods -o=custom-columns="POD NAME:.metadata.name,NODE:.spec.nodeName"

This command will output:

POD NAME           NODE
nginx-deployment-1  node-1
nginx-deployment-2  node-2

Namespace Specification:

By default, kubectl commands operate within the namespace defined by the current context. To target a specific namespace, you can use the -n or --namespace flag:

kubectl get pods -n 

To view resources across all namespaces, the -A or --all-namespaces flag is used:

kubectl get pods -A

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And to set a default namespace for the current context:

kubectl config set-context --current --namespace=ns_name

File Input:

The -f flag is used to specify a filename, directory, or URL when creating a resource.

kubectl create -f ./file_name

Label Filtering: 

You can use the -l flag to filter resources based on specific labels.

kubectl get pods -l name=label_name

Help Option:

To display help for kubectl commands, use the -h flag.

kubectl -h

Watch Mode:‍

You continuously monitor resource changes with the --watch (or -w) flag:

kubectl get pods -w

Sorting Output:‍

You can sort the output based on a specific field using the --sort-by flag:

kubectl get pods --sort-by=.metadata.name

When you working with kubectl, it involves typing lengthy commands, which can be time-consuming and error-prone. To improve efficiency, many developers create aliases for frequently used commands.

Setting Up a Basic Alias

alias k=kubectl
echo 'alias k=kubectl' >> ~/.bashrc

This allows you to use k in place of kubectl. 

You can use the kubectl-aliases repository, which provides hundreds of pre-defined aliases, enabling quicker command execution.

Cluster Management means setting up, viewing, and modifying your cluster. Command Description kubectl cluster-info Displays the endpoints and basic information about your Kubernetes cluster. kubectl config get-contexts Lists all contexts defined in your kubeconfig file. kubectl config current-context Shows the current active context. kubectl config use-context Switches the active context to the one you specify. kubectl config delete-context Removes a context from your kubeconfig file. kubectl api-versions Lists all the API versions available in the cluster. kubectl api-resources Lists all resource types available in your cluster, with details on API groups and namespaces. kubectl config view Displays the configuration details from your kubeconfig file (clusters, contexts, user settings). kubectl version Prints version info for both the kubectl client and the Kubernetes server.

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Shortcode = po

A Pod is the smallest unit in Kubernetes, representing a single instance of a running process in your cluster. It can contain one or more containers that share storage and network resources. Command Description kubectl get pods Lists all pods in the current namespace. kubectl describe pod Provides detailed information about the specified pod, including status, events, and container details. kubectl exec -it Executes the given command inside the specified pod interactively (the -it flags allow interactive terminal access). kubectl delete pod Deletes the specified pod from the cluster. kubectl run --image= Creates and runs a pod with the specified image. kubectl get pod -n Lists all pods in the specified namespace. kubectl exec -c Executes a command inside a specific container within a pod. kubectl top pod Displays resource usage (such as CPU and memory) for pods. kubectl annotate pod Adds or updates an annotation on the specified pod. kubectl get pods --field-selector=status.phase=Running Lists pods that are currently in the Running phase by filtering on the pod status. kubectl get pods --sort-by='.status.containerStatuses[0].restartCount' Sorts the list of pods by the restart count of the first container in each pod.

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Shortcode = rs

A ReplicaSet ensures a specified number of pod replicas are running. The main difference is that ReplicaSets support set-based label selectors. Command Description kubectl get rs Lists all ReplicaSets in the current namespace. kubectl get rs -o yaml Displays the configuration of the specified ReplicaSet in YAML format. kubectl get rs -o json Displays the configuration of the specified ReplicaSet in JSON format. kubectl describe rs Provides detailed information about the specified ReplicaSet. kubectl get rs --namespace= Lists all ReplicaSets in the specified namespace. kubectl delete rs --cascade=orphan Deletes the specified ReplicaSet but leaves its managed pods running (orphans the pods). kubectl delete rs Deletes the specified ReplicaSet along with all the pods it manages. kubectl scale rs --replicas= Adjusts (scales) the number of pods managed by the specified ReplicaSet to the given count. kubectl edit rs Opens the ReplicaSet configuration in your default editor, allowing you to make live changes. kubectl replace -f <rs_file.yaml> Replaces the existing ReplicaSet configuration with the one provided in the YAML file.

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Shortcode = ds

A DaemonSet ensures that a specific pod runs on all (or some) nodes in the cluster. This is useful for tasks like running a monitoring agent on every node. Command Description kubectl get daemonset Lists all DaemonSets in the current namespace. kubectl describe daemonset Provides detailed information about a specific DaemonSet. kubectl get daemonset -o yaml Displays the configuration of the specified DaemonSet in YAML format. kubectl get daemonset -o json Displays the configuration of the specified DaemonSet in JSON format. kubectl delete daemonset Deletes the specified DaemonSet from the cluster. kubectl label daemonset = Adds or updates a label on the specified DaemonSet. kubectl annotate daemonset = Adds or updates an annotation on the specified DaemonSet. kubectl rollout status daemonset Checks the status of a DaemonSet rollout. kubectl rollout history daemonset Displays the rollout history for a DaemonSet.

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Shortcode = sts

StatefulSets manage the deployment and scaling of pods, ensuring each has a unique, stable identity and persistent storage. This is important for stateful applications. Command Description kubectl get statefulset Lists all StatefulSets in the current namespace. kubectl describe statefulset Provides detailed information about the specified StatefulSet. kubectl get statefulset -o yaml Displays the configuration of the specified StatefulSet in YAML format. kubectl get statefulset -o json Displays the configuration of the specified StatefulSet in JSON format. kubectl edit statefulset Opens the configuration of the specified StatefulSet in your default text editor, allowing you to make live changes. kubectl scale statefulset --replicas= Adjusts the number of pod replicas managed by the specified StatefulSet to the provided number. kubectl rollout status statefulset Checks and displays the rollout status of the specified StatefulSet.

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Shortcode = ns

Namespaces provide a way to divide cluster resources between multiple users or applications. Command Description kubectl get namespace Lists all namespaces in your cluster (the current context’s namespaces). kubectl create namespace Creates a new namespace with the specified name. kubectl describe namespace Provides detailed information about the specified namespace. kubectl edit namespace Opens the configuration for the specified namespace in your default text editor so you can make live edits. kubectl delete namespace Deletes the specified namespace from your cluster along with all resources contained within it.

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Shortcode = svc 

A Service defines a logical set of pods and a policy to access them. It enables communication between different parts of your application and can expose your application to external traffic. Command Description kubectl get services Lists all services in the current namespace kubectl create service --tcp= Creates a new service of the specified type (for example, clusterip, nodeport, or loadbalancer) with the given name, mapping TCP on a given port kubectl edit service Opens an editor for editing the configuration of specified service kubectl describe service Provides detailed information about the specified service kubectl delete service Deletes the specified service from the cluster kubectl get endpoints Lists the endpoints (i.e., the IP addresses of the pods) that back the specified service kubectl expose deployment [deploy_name] Creates a service that exposes the specified deployment and possible resources for expose include pod (po), service (svc), replicaset (rs)

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Shortcode = sa

A ServiceAccount provides an identity for processes running in a pod, allowing them to interact with the Kubernetes API securely. Command Description kubectl get serviceaccounts Lists all service accounts in the current namespace kubectl describe serviceaccount Displays detailed information for the specified service account kubectl replace -f <sa.yaml> Replace (update) a service account with a new configuration kubectl delete serviceaccount Deletes the specified service account from the cluster.

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Shortcode = deploy

A Deployment provides declarative updates for pods and ReplicaSets. You can define the desired state of your application, and the Deployment controller changes the actual state to the desired state at a controlled rate. Command Description kubectl get deployment Lists all deployments in the current namespace. kubectl describe deployment Displays detailed information about the specified deployment kubectl create deployment --image= Creates a new deployment named using the specified container image kubectl edit deployment Opens the deployment configuration in your default text editor for live editing kubectl scale deployment --replicas= Adjusts the number of pod replicas managed by the deployment to the specified count. kubectl set image deployment/ = Updates the image for a specified container within the deployment kubectl rollout status deployment/ Shows the current rollout status of the deployment kubectl rollout pause deployment/ Pauses the rollout process, preventing further updates until resumed kubectl rollout resume deployment/ Resumes a paused deployment rollout kubectl rollout undo deployment/ Reverts the deployment to its previous revision kubectl rollout undo deployment/ --to-revision= Rolls back the deployment to a specific revision number kubectl delete deployment Deletes the specified deployment along with its managed pods

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Shortcode = ev

Events are records of what happened in your cluster, such as pod creations, deletions, or errors. Command Description kubectl get events Lists all events in the current namespace kubectl get events --field-selector type!=Normal Displays events that are not of type Normal kubectl get events --field-selector type=Warning Filters and displays only events of type Warning kubectl get events -w Watches for new events in real-time kubectl get events --field-selector involvedObject.name= Shows events related to a specific object such as a pod or node

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Logs are the output of your running applications and system components. Command Description kubectl logs Retrieves and displays the logs from the main container of the specified pod kubectl logs -f Streams the live logs from the specified pod kubectl logs --since=6h Displays logs from the specified pod that were generated within the last 6 hours kubectl logs --tail=50 Shows the last 50 lines of logs from the specified pod kubectl logs -f -c Streams live logs from a specific container within a pod kubectl logs > podfile.log Saves the logs from a pod to a file named podfile.log kubectl logs --previous Displays logs from the previous instance of a container in the specified pod

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Shortcode for ConfigMaps = cm

Secrets store sensitive information like passwords or keys, while ConfigMaps hold non-sensitive configuration data. Both allow you to decouple configuration artifacts from image content to keep your applications portable. Command Description kubectl get secrets Lists all secrets in the current namespace kubectl get configmaps Lists all ConfigMaps in the current namespace kubectl describe secret Provides detailed information about the specified secret kubectl delete secret Deletes the specified secret from the cluster kubectl describe configmap Provides detailed information about the specified ConfigMap kubectl create configmap --from-file= Creates a new ConfigMap with the given name using the contents of the file specified kubectl create secret --from-literal=key=value Creates a new secret of the specified type using a key-value pair

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Shortcode = no

A Node is a worker machine in Kubernetes. Command Description kubectl get nodes Lists all the nodes in your cluster kubectl describe node Provides detailed information about the specified node kubectl drain Prepares the node for maintenance by evicting all pods and marking the node as unschedulable kubectl uncordon Marks a previously cordoned (unschedulable) node as schedulable again allowing new pods to be scheduled on it kubectl label node = Adds or updates a label on the specified node kubectl cordon Marks the specified node as unschedulable kubectl taint node =: Applies a taint to the specified node kubectl top node Displays resource usage metrics (such as CPU and memory) for the specified node kubectl annotate node = Adds or updates an annotation on the specified node

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Shortcode for Persistent Volume = pv

Shortcode for Persistent Volume Claim = pvc

PersistentVolumes are storage resources in your cluster, and PersistentVolumeClaims are requests for storage by users. Command Description kubectl get pv Lists all Persistent Volumes in the cluster kubectl describe pv Provides detailed information about a specific Persistent Volume kubectl get pvc Lists all Persistent Volume Claims in the current namespace kubectl describe pvc Displays detailed information about a specific Persistent Volume Claim

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You can transfer files between your local system and a pod's container helping in debugging or data backup. Command Description kubectl cp /: Copies a file or directory from your local machine into a container in the specified pod and namespace. kubectl cp : -n Copies a file or directory from a container inside a pod (in the given namespace) to your local machine. kubectl cp /: Copies a file or directory from your local machine to the destination pod and namespace.

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Verbosity refers to the level of detail included in the logs generated by components like kubectl and kubelet. You can adjust the verbosity of kubectl commands. Command Description kubectl get --v= This is the general form for setting the verbosity level. It tells kubectl how much debugging output to include when executing the command on the specified resource type. kubectl get --v=0 Runs the command with minimal debug output (the default level). kubectl get --v=7 Provides a higher verbosity level where additional debug information is printed, including HTTPS request headers sent by the client. kubectl get --v=8 Increases the verbosity further. At level 8, HTTP request and response contents (body data) are also displayed.

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