Command line tool (kubectl) (2023)

Kubernetes provides a command line tool for communicating with a Kubernetes cluster'scontrol plane,using the Kubernetes API.

This tool is named kubectl.

For configuration, kubectl looks for a file named config in the $HOME/.kube directory.You can specify other kubeconfigfiles by setting the KUBECONFIG environment variable or by setting the--kubeconfig flag.

This overview covers kubectl syntax, describes the command operations, and provides common examples.For details about each command, including all the supported flags and subcommands, see thekubectl reference documentation.

For installation instructions, see Installing kubectl;for a quick guide, see the cheat sheet.If you're used to using the docker command-line tool, kubectl for Docker Users explains some equivalent commands for Kubernetes.

Syntax

Use the following syntax to run kubectl commands from your terminal window:

kubectl [command] [TYPE] [NAME] [flags]

where command, TYPE, NAME, and flags are:

  • command: Specifies the operation that you want to perform on one or more resources,for example create, get, describe, delete.

  • TYPE: Specifies the resource type. Resource types are case-insensitive andyou can specify the singular, plural, or abbreviated forms.For example, the following commands produce the same output:

    kubectl get pod pod1kubectl get pods pod1kubectl get po pod1
  • NAME: Specifies the name of the resource. Names are case-sensitive. If the name is omitted, details for all resources are displayed, for example kubectl get pods.

    When performing an operation on multiple resources, you can specify each resource by type and name or specify one or more files:

    • To specify resources by type and name:

      • To group resources if they are all the same type: TYPE1 name1 name2 name<#>.
        Example: kubectl get pod example-pod1 example-pod2

      • To specify multiple resource types individually: TYPE1/name1 TYPE1/name2 TYPE2/name3 TYPE<#>/name<#>.
        Example: kubectl get pod/example-pod1 replicationcontroller/example-rc1

    • To specify resources with one or more files: -f file1 -f file2 -f file<#>

      • Use YAML rather than JSON since YAML tends to be more user-friendly, especially for configuration files.
        Example: kubectl get -f ./pod.yaml
  • flags: Specifies optional flags. For example, you can use the -s or --server flags to specify the address and port of the Kubernetes API server.

Caution: Flags that you specify from the command line override default values and any corresponding environment variables.

If you need help, run kubectl help from the terminal window.

In-cluster authentication and namespace overrides

By default kubectl will first determine if it is running within a pod, and thus in a cluster. It starts by checking for the KUBERNETES_SERVICE_HOST and KUBERNETES_SERVICE_PORT environment variables and the existence of a service account token file at /var/run/secrets/kubernetes.io/serviceaccount/token. If all three are found in-cluster authentication is assumed.

To maintain backwards compatibility, if the POD_NAMESPACE environment variable is set during in-cluster authentication it will override the default namespace from the service account token. Any manifests or tools relying on namespace defaulting will be affected by this.

POD_NAMESPACE environment variable

If the POD_NAMESPACE environment variable is set, cli operations on namespaced resources will default to the variable value. For example, if the variable is set to seattle, kubectl get pods would return pods in the seattle namespace. This is because pods are a namespaced resource, and no namespace was provided in the command. Review the output of kubectl api-resources to determine if a resource is namespaced.

Explicit use of --namespace <value> overrides this behavior.

How kubectl handles ServiceAccount tokens

If:

  • there is Kubernetes service account token file mounted at/var/run/secrets/kubernetes.io/serviceaccount/token, and
  • the KUBERNETES_SERVICE_HOST environment variable is set, and
  • the KUBERNETES_SERVICE_PORT environment variable is set, and
  • you don't explicitly specify a namespace on the kubectl command line

then kubectl assumes it is running in your cluster. The kubectl tool looks up thenamespace of that ServiceAccount (this is the same as the namespace of the Pod)and acts against that namespace. This is different from what happens outside of acluster; when kubectl runs outside a cluster and you don't specify a namespace,the kubectl command acts against the namespace set for the current context in yourclient configuration. To change the default namespace for your kubectl you can use thefollowing command:

kubectl config set-context --current --namespace=<namespace-name>

Operations

The following table includes short descriptions and the general syntax for all of the kubectl operations:

OperationSyntaxDescription
alphakubectl alpha SUBCOMMAND [flags]List the available commands that correspond to alpha features, which are not enabled in Kubernetes clusters by default.
annotatekubectl annotate (-f FILENAME | TYPE NAME | TYPE/NAME) KEY_1=VAL_1 ... KEY_N=VAL_N [--overwrite] [--all] [--resource-version=version] [flags]Add or update the annotations of one or more resources.
api-resourceskubectl api-resources [flags]List the API resources that are available.
api-versionskubectl api-versions [flags]List the API versions that are available.
applykubectl apply -f FILENAME [flags]Apply a configuration change to a resource from a file or stdin.
attachkubectl attach POD -c CONTAINER [-i] [-t] [flags]Attach to a running container either to view the output stream or interact with the container (stdin).
authkubectl auth [flags] [options]Inspect authorization.
autoscalekubectl autoscale (-f FILENAME | TYPE NAME | TYPE/NAME) [--min=MINPODS] --max=MAXPODS [--cpu-percent=CPU] [flags]Automatically scale the set of pods that are managed by a replication controller.
certificatekubectl certificate SUBCOMMAND [options]Modify certificate resources.
cluster-infokubectl cluster-info [flags]Display endpoint information about the master and services in the cluster.
completionkubectl completion SHELL [options]Output shell completion code for the specified shell (bash or zsh).
configkubectl config SUBCOMMAND [flags]Modifies kubeconfig files. See the individual subcommands for details.
convertkubectl convert -f FILENAME [options]Convert config files between different API versions. Both YAML and JSON formats are accepted. Note - requires kubectl-convert plugin to be installed.
cordonkubectl cordon NODE [options]Mark node as unschedulable.
cpkubectl cp <file-spec-src> <file-spec-dest> [options]Copy files and directories to and from containers.
createkubectl create -f FILENAME [flags]Create one or more resources from a file or stdin.
deletekubectl delete (-f FILENAME | TYPE [NAME | /NAME | -l label | --all]) [flags]Delete resources either from a file, stdin, or specifying label selectors, names, resource selectors, or resources.
describekubectl describe (-f FILENAME | TYPE [NAME_PREFIX | /NAME | -l label]) [flags]Display the detailed state of one or more resources.
diffkubectl diff -f FILENAME [flags]Diff file or stdin against live configuration.
drainkubectl drain NODE [options]Drain node in preparation for maintenance.
editkubectl edit (-f FILENAME | TYPE NAME | TYPE/NAME) [flags]Edit and update the definition of one or more resources on the server by using the default editor.
execkubectl exec POD [-c CONTAINER] [-i] [-t] [flags] [-- COMMAND [args...]]Execute a command against a container in a pod.
explainkubectl explain [--recursive=false] [flags]Get documentation of various resources. For instance pods, nodes, services, etc.
exposekubectl expose (-f FILENAME | TYPE NAME | TYPE/NAME) [--port=port] [--protocol=TCP|UDP] [--target-port=number-or-name] [--name=name] [--external-ip=external-ip-of-service] [--type=type] [flags]Expose a replication controller, service, or pod as a new Kubernetes service.
getkubectl get (-f FILENAME | TYPE [NAME | /NAME | -l label]) [--watch] [--sort-by=FIELD] [[-o | --output]=OUTPUT_FORMAT] [flags]List one or more resources.
kustomizekubectl kustomize <dir> [flags] [options]List a set of API resources generated from instructions in a kustomization.yaml file. The argument must be the path to the directory containing the file, or a git repository URL with a path suffix specifying same with respect to the repository root.
labelkubectl label (-f FILENAME | TYPE NAME | TYPE/NAME) KEY_1=VAL_1 ... KEY_N=VAL_N [--overwrite] [--all] [--resource-version=version] [flags]Add or update the labels of one or more resources.
logskubectl logs POD [-c CONTAINER] [--follow] [flags]Print the logs for a container in a pod.
optionskubectl optionsList of global command-line options, which apply to all commands.
patchkubectl patch (-f FILENAME | TYPE NAME | TYPE/NAME) --patch PATCH [flags]Update one or more fields of a resource by using the strategic merge patch process.
pluginkubectl plugin [flags] [options]Provides utilities for interacting with plugins.
port-forwardkubectl port-forward POD [LOCAL_PORT:]REMOTE_PORT [...[LOCAL_PORT_N:]REMOTE_PORT_N] [flags]Forward one or more local ports to a pod.
proxykubectl proxy [--port=PORT] [--www=static-dir] [--www-prefix=prefix] [--api-prefix=prefix] [flags]Run a proxy to the Kubernetes API server.
replacekubectl replace -f FILENAMEReplace a resource from a file or stdin.
rolloutkubectl rollout SUBCOMMAND [options]Manage the rollout of a resource. Valid resource types include: deployments, daemonsets and statefulsets.
runkubectl run NAME --image=image [--env="key=value"] [--port=port] [--dry-run=server|client|none] [--overrides=inline-json] [flags]Run a specified image on the cluster.
scalekubectl scale (-f FILENAME | TYPE NAME | TYPE/NAME) --replicas=COUNT [--resource-version=version] [--current-replicas=count] [flags]Update the size of the specified replication controller.
setkubectl set SUBCOMMAND [options]Configure application resources.
taintkubectl taint NODE NAME KEY_1=VAL_1:TAINT_EFFECT_1 ... KEY_N=VAL_N:TAINT_EFFECT_N [options]Update the taints on one or more nodes.
topkubectl top [flags] [options]Display Resource (CPU/Memory/Storage) usage.
uncordonkubectl uncordon NODE [options]Mark node as schedulable.
versionkubectl version [--client] [flags]Display the Kubernetes version running on the client and server.
waitkubectl wait ([-f FILENAME] | resource.group/resource.name | resource.group [(-l label | --all)]) [--for=delete|--for condition=available] [options]Experimental: Wait for a specific condition on one or many resources.

To learn more about command operations, see the kubectl reference documentation.

Resource types

The following table includes a list of all the supported resource types and their abbreviated aliases.

(This output can be retrieved from kubectl api-resources, and was accurate as of Kubernetes 1.25.0)

NAMESHORTNAMESAPIVERSIONNAMESPACEDKIND
bindingsv1trueBinding
componentstatusescsv1falseComponentStatus
configmapscmv1trueConfigMap
endpointsepv1trueEndpoints
eventsevv1trueEvent
limitrangeslimitsv1trueLimitRange
namespacesnsv1falseNamespace
nodesnov1falseNode
persistentvolumeclaimspvcv1truePersistentVolumeClaim
persistentvolumespvv1falsePersistentVolume
podspov1truePod
podtemplatesv1truePodTemplate
replicationcontrollersrcv1trueReplicationController
resourcequotasquotav1trueResourceQuota
secretsv1trueSecret
serviceaccountssav1trueServiceAccount
servicessvcv1trueService
mutatingwebhookconfigurationsadmissionregistration.k8s.io/v1falseMutatingWebhookConfiguration
validatingwebhookconfigurationsadmissionregistration.k8s.io/v1falseValidatingWebhookConfiguration
customresourcedefinitionscrd,crdsapiextensions.k8s.io/v1falseCustomResourceDefinition
apiservicesapiregistration.k8s.io/v1falseAPIService
controllerrevisionsapps/v1trueControllerRevision
daemonsetsdsapps/v1trueDaemonSet
deploymentsdeployapps/v1trueDeployment
replicasetsrsapps/v1trueReplicaSet
statefulsetsstsapps/v1trueStatefulSet
tokenreviewsauthentication.k8s.io/v1falseTokenReview
localsubjectaccessreviewsauthorization.k8s.io/v1trueLocalSubjectAccessReview
selfsubjectaccessreviewsauthorization.k8s.io/v1falseSelfSubjectAccessReview
selfsubjectrulesreviewsauthorization.k8s.io/v1falseSelfSubjectRulesReview
subjectaccessreviewsauthorization.k8s.io/v1falseSubjectAccessReview
horizontalpodautoscalershpaautoscaling/v2trueHorizontalPodAutoscaler
cronjobscjbatch/v1trueCronJob
jobsbatch/v1trueJob
certificatesigningrequestscsrcertificates.k8s.io/v1falseCertificateSigningRequest
leasescoordination.k8s.io/v1trueLease
endpointslicesdiscovery.k8s.io/v1trueEndpointSlice
eventsevevents.k8s.io/v1trueEvent
flowschemasflowcontrol.apiserver.k8s.io/v1beta2falseFlowSchema
prioritylevelconfigurationsflowcontrol.apiserver.k8s.io/v1beta2falsePriorityLevelConfiguration
ingressclassesnetworking.k8s.io/v1falseIngressClass
ingressesingnetworking.k8s.io/v1trueIngress
networkpoliciesnetpolnetworking.k8s.io/v1trueNetworkPolicy
runtimeclassesnode.k8s.io/v1falseRuntimeClass
poddisruptionbudgetspdbpolicy/v1truePodDisruptionBudget
podsecuritypoliciespsppolicy/v1beta1falsePodSecurityPolicy
clusterrolebindingsrbac.authorization.k8s.io/v1falseClusterRoleBinding
clusterrolesrbac.authorization.k8s.io/v1falseClusterRole
rolebindingsrbac.authorization.k8s.io/v1trueRoleBinding
rolesrbac.authorization.k8s.io/v1trueRole
priorityclassespcscheduling.k8s.io/v1falsePriorityClass
csidriversstorage.k8s.io/v1falseCSIDriver
csinodesstorage.k8s.io/v1falseCSINode
csistoragecapacitiesstorage.k8s.io/v1trueCSIStorageCapacity
storageclassesscstorage.k8s.io/v1falseStorageClass
volumeattachmentsstorage.k8s.io/v1falseVolumeAttachment

Output options

Use the following sections for information about how you can format or sort the output of certain commands. For details about which commands support the various output options, see the kubectl reference documentation.

Formatting output

The default output format for all kubectl commands is the human readable plain-text format. To output details to your terminal window in a specific format, you can add either the -o or --output flags to a supported kubectl command.

Syntax

kubectl [command] [TYPE] [NAME] -o <output_format>

Depending on the kubectl operation, the following output formats are supported:

Output formatDescription
-o custom-columns=<spec>Print a table using a comma separated list of custom columns.
-o custom-columns-file=<filename>Print a table using the custom columns template in the <filename> file.
-o jsonOutput a JSON formatted API object.
-o jsonpath=<template>Print the fields defined in a jsonpath expression.
-o jsonpath-file=<filename>Print the fields defined by the jsonpath expression in the <filename> file.
-o namePrint only the resource name and nothing else.
-o wideOutput in the plain-text format with any additional information. For pods, the node name is included.
-o yamlOutput a YAML formatted API object.
Example

In this example, the following command outputs the details for a single pod as a YAML formatted object:

kubectl get pod web-pod-13je7 -o yaml

Remember: See the kubectl reference documentationfor details about which output format is supported by each command.

Custom columns

To define custom columns and output only the details that you want into a table, you can use the custom-columns option.You can choose to define the custom columns inline or use a template file: -o custom-columns=<spec> or -o custom-columns-file=<filename>.

Examples

Inline:

kubectl get pods <pod-name> -o custom-columns=NAME:.metadata.name,RSRC:.metadata.resourceVersion

Template file:

kubectl get pods <pod-name> -o custom-columns-file=template.txt

where the template.txt file contains:

NAME RSRCmetadata.name metadata.resourceVersion

The result of running either command is similar to:

NAME RSRCsubmit-queue 610995

Server-side columns

kubectl supports receiving specific column information from the server about objects.This means that for any given resource, the server will return columns and rows relevant to that resource, for the client to print.This allows for consistent human-readable output across clients used against the same cluster, by having the server encapsulate the details of printing.

This feature is enabled by default. To disable it, add the--server-print=false flag to the kubectl get command.

Examples

To print information about the status of a pod, use a command like the following:

kubectl get pods <pod-name> --server-print=false

The output is similar to:

NAME AGEpod-name 1m

Sorting list objects

To output objects to a sorted list in your terminal window, you can add the --sort-by flag to a supported kubectl command. Sort your objects by specifying any numeric or string field with the --sort-by flag. To specify a field, use a jsonpath expression.

Syntax

kubectl [command] [TYPE] [NAME] --sort-by=<jsonpath_exp>
Example

To print a list of pods sorted by name, you run:

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

Examples: Common operations

Use the following set of examples to help you familiarize yourself with running the commonly used kubectl operations:

kubectl apply - Apply or Update a resource from a file or stdin.

# Create a service using the definition in example-service.yaml.kubectl apply -f example-service.yaml# Create a replication controller using the definition in example-controller.yaml.kubectl apply -f example-controller.yaml# Create the objects that are defined in any .yaml, .yml, or .json file within the <directory> directory.kubectl apply -f <directory>

kubectl get - List one or more resources.

# List all pods in plain-text output format.kubectl get pods# List all pods in plain-text output format and include additional information (such as node name).kubectl get pods -o wide# List the replication controller with the specified name in plain-text output format. Tip: You can shorten and replace the 'replicationcontroller' resource type with the alias 'rc'.kubectl get replicationcontroller <rc-name># List all replication controllers and services together in plain-text output format.kubectl get rc,services# List all daemon sets in plain-text output format.kubectl get ds# List all pods running on node server01kubectl get pods --field-selector=spec.nodeName=server01

kubectl describe - Display detailed state of one or more resources, including the uninitialized ones by default.

# Display the details of the node with name <node-name>.kubectl describe nodes <node-name># Display the details of the pod with name <pod-name>.kubectl describe pods/<pod-name># Display the details of all the pods that are managed by the replication controller named <rc-name>.# Remember: Any pods that are created by the replication controller get prefixed with the name of the replication controller.kubectl describe pods <rc-name># Describe all podskubectl describe pods

Note: The kubectl get command is usually used for retrieving one or moreresources of the same resource type. It features a rich set of flags that allowsyou to customize the output format using the -o or --output flag, for example.You can specify the -w or --watch flag to start watching updates to a particularobject. The kubectl describe command is more focused on describing the manyrelated aspects of a specified resource. It may invoke several API calls to theAPI server to build a view for the user. For example, the kubectl describe nodecommand retrieves not only the information about the node, but also a summary ofthe pods running on it, the events generated for the node etc.

kubectl delete - Delete resources either from a file, stdin, or specifying label selectors, names, resource selectors, or resources.

# Delete a pod using the type and name specified in the pod.yaml file.kubectl delete -f pod.yaml# Delete all the pods and services that have the label '<label-key>=<label-value>'.kubectl delete pods,services -l <label-key>=<label-value># Delete all pods, including uninitialized ones.kubectl delete pods --all

kubectl exec - Execute a command against a container in a pod.

# Get output from running 'date' from pod <pod-name>. By default, output is from the first container.kubectl exec <pod-name> -- date# Get output from running 'date' in container <container-name> of pod <pod-name>.kubectl exec <pod-name> -c <container-name> -- date# Get an interactive TTY and run /bin/bash from pod <pod-name>. By default, output is from the first container.kubectl exec -ti <pod-name> -- /bin/bash

kubectl logs - Print the logs for a container in a pod.

# Return a snapshot of the logs from pod <pod-name>.kubectl logs <pod-name># Start streaming the logs from pod <pod-name>. This is similar to the 'tail -f' Linux command.kubectl logs -f <pod-name>

kubectl diff - View a diff of the proposed updates to a cluster.

# Diff resources included in "pod.json".kubectl diff -f pod.json# Diff file read from stdin.cat service.yaml | kubectl diff -f -

Examples: Creating and using plugins

Use the following set of examples to help you familiarize yourself with writing and using kubectl plugins:

# create a simple plugin in any language and name the resulting executable file# so that it begins with the prefix "kubectl-"cat ./kubectl-hello
#!/bin/sh# this plugin prints the words "hello world"echo "hello world"

With a plugin written, let's make it executable:

chmod a+x ./kubectl-hello# and move it to a location in our PATHsudo mv ./kubectl-hello /usr/local/binsudo chown root:root /usr/local/bin# You have now created and "installed" a kubectl plugin.# You can begin using this plugin by invoking it from kubectl as if it were a regular commandkubectl hello
hello world
# You can "uninstall" a plugin, by removing it from the folder in your# $PATH where you placed itsudo rm /usr/local/bin/kubectl-hello

In order to view all of the plugins that are available to kubectl, usethe kubectl plugin list subcommand:

kubectl plugin list

The output is similar to:

The following kubectl-compatible plugins are available:/usr/local/bin/kubectl-hello/usr/local/bin/kubectl-foo/usr/local/bin/kubectl-bar

kubectl plugin list also warns you about plugins that are notexecutable, or that are shadowed by other plugins; for example:

sudo chmod -x /usr/local/bin/kubectl-foo # remove execute permissionkubectl plugin list
The following kubectl-compatible plugins are available:/usr/local/bin/kubectl-hello/usr/local/bin/kubectl-foo - warning: /usr/local/bin/kubectl-foo identified as a plugin, but it is not executable/usr/local/bin/kubectl-barerror: one plugin warning was found

You can think of plugins as a means to build more complex functionality on topof the existing kubectl commands:

cat ./kubectl-whoami

The next few examples assume that you already made kubectl-whoami havethe following contents:

#!/bin/bash# this plugin makes use of the `kubectl config` command in order to output# information about the current user, based on the currently selected contextkubectl config view --template='{{ range .contexts }}{{ if eq .name "'$(kubectl config current-context)'" }}Current user: {{ printf "%s\n" .context.user }}{{ end }}{{ end }}'

Running the above command gives you an output containing the user for thecurrent context in your KUBECONFIG file:

# make the file executablesudo chmod +x ./kubectl-whoami# and move it into your PATHsudo mv ./kubectl-whoami /usr/local/binkubectl whoamiCurrent user: plugins-user

What's next

  • Read the kubectl reference documentation:
    • the kubectl command reference
    • the command line arguments reference
  • Learn about kubectl usage conventions
  • Read about JSONPath support in kubectl
  • Read about how to extend kubectl with plugins
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