Kubectl
Kubectl configuration
# CONFIG VIEW
kubectl config view # Show Merged kubeconfig settings.
KUBECONFIG=~/.kube/config:~/.kube/kubconfig2 # Use multiple kubeconfig files at the same time and view merged config
kubectl config view -o jsonpath='{.users[*].name}' # get a list of users
# CONFIG CONTEXT
kubectl config get-contexts # display list of contexts
kubectl config current-context # display the current-context
kubectl config use-context my-cluster-name # set the default context to my-cluster-name
kubectl config set-context --current --namespace=ggckad-s2 # permanently save the namespace for all subsequent kubectl commands in that context.
kubectl config set-context gce --user=cluster-admin --namespace=foo \
&& kubectl config use-context gce # set a context utilizing a specific username and namespace.
# CONFIG CLUSTER
kubectl config set-cluster my-cluster-name # set a cluster entry in the kubeconfig
kubectl config set-cluster my-cluster-name --proxy-url=my-proxy-url # configure the URL to a proxy server to use for requests made by this client in the kubeconfig
# CONFIG USERS & CREDENTIALS
kubectl config set-credentials kubeuser/foo.kubernetes.com \
--username=kubeuser --password=kubepassword # add a new user to your kubeconf that supports basic auth
kubectl config unset users.foo # delete user foo
Resource management
Creating resources
# APPLY
kubectl apply -f ./my-manifest.yaml # create resource(s)
kubectl apply -f ./my1.yaml -f ./my2.yaml # create from multiple files
kubectl apply -f ./dir # create resource(s) in all manifest files in dir
kubectl apply -f https://git.io/vPieo # create resource(s) from url
# CREATE
kubectl create deployment nginx --image=nginx # start a single instance of nginx
kubectl create job hello --image=busybox:1.28 -- echo "Hello World" # create a Job which prints "Hello World"
kubectl create cronjob hello --image=busybox:1.28 \
--schedule="*/1 * * * *" -- echo "Hello World" # create a CronJob that prints "Hello World" every minute
Viewing and finding resources
# GET SERVICE/S
kubectl get services # List all services in the namespace
kubectl get services --sort-by=.metadata.name # List Services Sorted by Name
# GET POD/S
kubectl get pod my-pod -o yaml # Get a pod's YAML
kubectl get pods # List all pods in the namespace
kubectl get pods --all-namespaces # List all pods in all namespaces
kubectl get pods -o wide # List all pods in the current namespace, with more details
kubectl get pods --show-labels # Show labels for all pods (or any other Kubernetes object that supports labelling)
kubectl get pods --sort-by='.status.containerStatuses[0].restartCount' # List pods Sorted by Restart Count
kubectl get pods --selector=app=cassandra -o \
jsonpath='{.items[*].metadata.labels.version}' # Get the version label of all pods with label app=cassandra
kubectl get pods --field-selector=status.phase=Running # Get all running pods in the namespace
kubectl get pods -o json | jq -c 'paths|join(".")' # Produce a period-delimited tree of all keys returned for pods, etc
kubectl get pods -o json \
| jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' \
| grep -v null | sort | uniq # List all Secrets currently in use by a pod
sel=${$(kubectl get rc my-rc --output=json | jq -j '.spec.selector | to_entries | .[] | "\(.key)=\(.value),"')%?} # List Names of Pods that belong to Particular RC. "jq" command useful for transformations that are too complex for jsonpath, it can be found at https://stedolan.github.io/jq/
echo $(kubectl get pods --selector=$sel --output=jsonpath={.items..metadata.name})
kubectl get pods --all-namespaces -o jsonpath='{range .items[*].status.initContainerStatuses[*]}{.containerID}{"\n"}{end}' | cut -d/ -f3 # List all containerIDs of initContainer of all pods. Helpful when cleaning up stopped containers, while avoiding removal of initContainers.
# GET DEPLOYMENT
kubectl get deployment my-dep # List a particular deployment
kubectl get deployment nginx-deployment --subresource=status # Get a deployment's status subresource
# GET NODE/S
kubectl get node --selector='!node-role.kubernetes.io/control-plane' # Get all worker nodes (use a selector to exclude results that have a label named 'node-role.kubernetes.io/control-plane')
kubectl get nodes -o json | jq -c 'paths|join(".")' # Produce a period-delimited tree of all keys returned for nodes. Helpful when locating a key within a complex nested JSON structure
kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}' # Get ExternalIPs of all nodes
JSONPATH='{range .items[*]}{@.metadata.name}:{range @.status.conditions[*]}{@.type}={@.status};{end}{end}' \
&& kubectl get nodes -o jsonpath="$JSONPATH" | grep "Ready=True" # Check which nodes are ready
# GET SECRET
kubectl get secret my-secret --template='{{index .data "key-name-with-dashes"}}' # Retrieve a base64 encoded value with dashes instead of underscores.
kubectl get secret my-secret -o go-template='{{range $k,$v := .data}}{{"### "}}{{$k}}{{"\n"}}{{$v|base64decode}}{{"\n\n"}}{{end}}' # Output decoded secrets without external tools
# GET PERSISTENTVOLUMES
kubectl get pv --sort-by=.spec.capacity.storage # List PersistentVolumes sorted by capacity
# GET CONFIGMAP
kubectl get configmap myconfig -o jsonpath='{.data.ca\.crt}' # Retrieve the value of a key with dots, e.g. 'ca.crt'
# GET EVENTS
kubectl get events --sort-by=.metadata.creationTimestamp # List Events sorted by timestamp
kubectl events --types=Warning # List all warning events
# DESCRIBE
kubectl describe nodes my-node # Describe commands with verbose output
kubectl describe pods my-pod
# DIFF
kubectl diff -f ./my-manifest.yaml # Compares the current state of the cluster against the state that the cluster would be in if the manifest was applied.
# ETC
# Produce ENV for all pods, assuming you have a default container for the pods, default namespace and the `env` command is supported.
# Helpful when running any supported command across all pods, not just `env`
for pod in $(kubectl get po --output=jsonpath={.items..metadata.name}); do echo $pod && kubectl exec -it $pod -- env; done
Updating resources
kubectl set image deployment/frontend www=image:v2 # Rolling update "www" containers of "frontend" deployment, updating the image
kubectl rollout history deployment/frontend # Check the history of deployments including the revision
kubectl rollout undo deployment/frontend # Rollback to the previous deployment
kubectl rollout undo deployment/frontend --to-revision=2 # Rollback to a specific revision
kubectl rollout status -w deployment/frontend # Watch rolling update status of "frontend" deployment until completion
kubectl rollout restart deployment/frontend # Rolling restart of the "frontend" deployment
cat pod.json | kubectl replace -f - # Replace a pod based on the JSON passed into stdin
kubectl replace --force -f ./pod.json # Force replace, delete and then re-create the resource. Will cause a service outage.
kubectl expose rc nginx --port=80 --target-port=8000 # Create a service for a replicated nginx, which serves on port 80 and connects to the containers on port 8000
kubectl get pod mypod -o yaml \
| sed 's/\(image: myimage\):.*$/\1:v4/' | kubectl replace -f - # Update a single-container pod's image version (tag) to v4
kubectl label pods my-pod new-label=awesome # Add a Label
kubectl label pods my-pod new-label- # Remove a label
kubectl annotate pods my-pod icon-url=http://goo.gl/XXBTWq # Add an annotation
kubectl autoscale deployment foo --min=2 --max=10 # Auto scale a deployment "foo"
Patching resources
# Partially update a node
kubectl patch node k8s-node-1 -p '{"spec":{"unschedulable":true}}'
# Update a container's image; spec.containers[*].name is required because it's a merge key
kubectl patch pod valid-pod -p '{"spec":{"containers":[{"name":"kubernetes-serve-hostname","image":"new image"}]}}'
# Update a container's image using a json patch with positional arrays
kubectl patch pod valid-pod --type='json' -p='[{"op": "replace", "path": "/spec/containers/0/image", "value":"new image"}]'
# Disable a deployment livenessProbe using a json patch with positional arrays
kubectl patch deployment valid-deployment --type json -p='[{"op": "remove", "path": "/spec/template/spec/containers/0/livenessProbe"}]'
# Add a new element to a positional array
kubectl patch sa default --type='json' -p='[{"op": "add", "path": "/secrets/1", "value": {"name": "whatever" } }]'
# Update a deployment's replica count by patching its scale subresource
kubectl patch deployment nginx-deployment --subresource='scale' --type='merge' -p '{"spec":{"replicas":2}}'
Editing resources
kubectl edit svc/docker-registry # Edit the service named docker-registry
KUBE_EDITOR="nano" kubectl edit svc/docker-registry # Use an alternative editor
Scaling resources
kubectl scale --replicas=3 rs/foo # Scale a replicaset named 'foo' to 3
kubectl scale --replicas=3 -f foo.yaml # Scale a resource specified in "foo.yaml" to 3
kubectl scale --current-replicas=2 --replicas=3 deployment/mysql # If the deployment named mysql's current size is 2, scale mysql to 3
kubectl scale --replicas=5 rc/foo rc/bar rc/baz # Scale multiple replication controllers
Deleting resources
kubectl delete -f ./pod.json # Delete a pod using the type and name specified in pod.json
kubectl delete pod unwanted --now # Delete a pod with no grace period
kubectl delete pod,service baz foo # Delete pods and services with same names "baz" and "foo"
kubectl delete pods,services -l name=myLabel # Delete pods and services with label name=myLabel
kubectl -n my-ns delete pod,svc --all # Delete all pods and services in namespace my-ns,
# Delete all pods matching the awk pattern1 or pattern2
kubectl get pods -n mynamespace --no-headers=true | awk '/pattern1|pattern2/{print $1}' | xargs kubectl delete -n mynamespace pod
Interaction with resources
Interacting with running Pods
# LOGS
kubectl logs my-pod # dump pod logs (stdout)
kubectl logs -l name=myLabel # dump pod logs, with label name=myLabel (stdout)
kubectl logs my-pod --previous # dump pod logs (stdout) for a previous instantiation of a container
kubectl logs my-pod -c my-container # dump pod container logs (stdout, multi-container case)
kubectl logs -l name=myLabel -c my-container # dump pod logs, with label name=myLabel (stdout)
kubectl logs my-pod -c my-container --previous # dump pod container logs (stdout, multi-container case) for a previous instantiation of a container
kubectl logs -f my-pod # stream pod logs (stdout)
kubectl logs -f my-pod -c my-container # stream pod container logs (stdout, multi-container case)
kubectl logs -f -l name=myLabel --all-containers # stream all pods logs with label name=myLabel (stdout)
# RUN
kubectl run -i --tty busybox --image=busybox:1.28 -- sh # Run pod as interactive shell
kubectl run nginx --image=nginx -n mynamespace # Start a single instance of nginx pod in the namespace of mynamespace
kubectl run nginx --image=nginx --dry-run=client -o yaml > pod.yaml
# Generate spec for running pod nginx and write it into a file called pod.yaml
# ATTACH
kubectl attach my-pod -i # Attach to Running Container
# PORT-FORWARD
kubectl port-forward my-pod 5000:6000 # Listen on port 5000 on the local machine and forward to port 6000 on my-pod
# EXEC
kubectl exec my-pod -- ls / # Run command in existing pod (1 container case)
kubectl exec --stdin --tty my-pod -- /bin/sh # Interactive shell access to a running pod (1 container case)
kubectl exec -ti <pod name> -- bash # Interactive bash access to a running pod (1 container case)
kubectl exec my-pod -c my-container -- ls / # Run command in existing pod (multi-container case)
# TOP
kubectl top pod POD_NAME --containers # Show metrics for a given pod and its containers
kubectl top pod POD_NAME --sort-by=cpu # Show metrics for a given pod and sort it by 'cpu' or 'memory'
Copying files and directories to and from containers
kubectl cp /tmp/foo_dir my-pod:/tmp/bar_dir # Copy /tmp/foo_dir local directory to /tmp/bar_dir in a remote pod in the current namespace
kubectl cp /tmp/foo my-pod:/tmp/bar -c my-container # Copy /tmp/foo local file to /tmp/bar in a remote pod in a specific container
kubectl cp /tmp/foo my-namespace/my-pod:/tmp/bar # Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace my-namespace
kubectl cp my-namespace/my-pod:/tmp/foo /tmp/bar # Copy /tmp/foo from a remote pod to /tmp/bar locally
tar cf - /tmp/foo | kubectl exec -i -n my-namespace my-pod -- tar xf - -C /tmp/bar # Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace my-namespace
kubectl exec -n my-namespace my-pod -- tar cf - /tmp/foo | tar xf - -C /tmp/bar # Copy /tmp/foo from a remote pod to /tmp/bar locally
Interacting with Deployments and Services
kubectl logs deploy/my-deployment # dump Pod logs for a Deployment (single-container case)
kubectl logs deploy/my-deployment -c my-container # dump Pod logs for a Deployment (multi-container case)
kubectl port-forward svc/my-service 5000 # listen on local port 5000 and forward to port 5000 on Service backend
kubectl port-forward svc/my-service 5000:my-service-port # listen on local port 5000 and forward to Service target port with name <my-service-port>
kubectl port-forward deploy/my-deployment 5000:6000 # listen on local port 5000 and forward to port 6000 on a Pod created by <my-deployment>
kubectl exec deploy/my-deployment -- ls # run command in first Pod and first container in Deployment (single- or multi-container cases)
Interacting with Nodes and cluster
kubectl cordon my-node # Mark my-node as unschedulable
kubectl drain my-node # Drain my-node in preparation for maintenance
kubectl uncordon my-node # Mark my-node as schedulable
kubectl top node my-node # Show metrics for a given node
kubectl cluster-info # Display addresses of the master and services
kubectl cluster-info dump # Dump current cluster state to stdout
kubectl cluster-info dump --output-directory=/path/to/cluster-state # Dump current cluster state to /path/to/cluster-state
# View existing taints on which exist on current nodes.
kubectl get nodes -o='custom-columns=NodeName:.metadata.name,TaintKey:.spec.taints[*].key,TaintValue:.spec.taints[*].value,TaintEffect:.spec.taints[*].effect'
# If a taint with that key and effect already exists, its value is replaced as specified.
kubectl taint nodes foo dedicated=special-user:NoSchedule
Resource types
kubectl api-resources
kubectl api-resources --namespaced=true # All namespaced resources
kubectl api-resources --namespaced=false # All non-namespaced resources
kubectl api-resources -o name # All resources with simple output (only the resource name)
kubectl api-resources -o wide # All resources with expanded (aka "wide") output
kubectl api-resources --verbs=list,get # All resources that support the "list" and "get" request verbs
kubectl api-resources --api-group=extensions # All resources in the "extensions" API group
Formatting output
# To output details to your terminal window in a specific format, add the -o (or --output) flag to a supported kubectl command.
# Output format Description
-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=json Output 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=name Print only the resource name and nothing else
-o=wide Output in the plain-text format with any additional information, and for pods, the node name is included
-o=yaml Output a YAML formatted API object
# EXAMPLES using -o=custom-columns:
# All images running in a cluster
kubectl get pods -A -o=custom-columns='DATA:spec.containers[*].image'
# All images running in namespace: default, grouped by Pod
kubectl get pods --namespace default --output=custom-columns="NAME:.metadata.name,IMAGE:.spec.containers[*].image"
# All images excluding "registry.k8s.io/coredns:1.6.2"
kubectl get pods -A -o=custom-columns='DATA:spec.containers[?(@.image!="registry.k8s.io/coredns:1.6.2")].image'
# All fields under metadata regardless of name
kubectl get pods -A -o=custom-columns='DATA:metadata.*'
Kubectl output verbosity and debugging
# Kubectl verbosity is controlled with the -v or --v flags followed by an integer representing the log level. General Kubernetes logging conventions and the associated log levels are described here.
# Verbosity Description
--v=0 Generally useful for this to always be visible to a cluster operator.
--v=1 A reasonable default log level if you don't want verbosity.
--v=2 Useful steady state information about the service and important log messages that may correlate to significant changes in the system. This is the recommended default log level for most systems.
--v=3 Extended information about changes.
--v=4 Debug level verbosity.
--v=5 Trace level verbosity.
--v=6 Display requested resources.
--v=7 Display HTTP request headers.
--v=8 Display HTTP request contents.
--v=9 Display HTTP request contents without truncation of contents.
Etc.
kubectl explain pods # get the documentation for pod manifests