Kubectl Context and Configuration:
kubectl config view # Show Merged kubeconfig settings.
# use multiple kubeconfig files at the same time and view merged config
KUBECONFIG=~/.kube/config:~/.kube/kubconfig2
kubectl config view
# get the password for the e2e user
kubectl config view -o jsonpath='{.users[?(@.name == "e2e")].user.password}'
kubectl config view -o jsonpath='{.users[].name}' # display the first user
kubectl config view -o jsonpath='{.users[*].name}' # get a list of users
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
# add a new cluster to your kubeconf that supports basic auth
kubectl config set-credentials kubeuser/foo.kubernetes.com --username=kubeuser --password=kubepassword
# permanently save the namespace for all subsequent kubectl commands in that context.
kubectl config set-context --current --namespace=ggckad-s2
# set a context utilizing a specific username and namespace.
kubectl config set-context gce --user=cluster-admin --namespace=foo \
&& kubectl config use-context gce
kubectl config unset users.foo # delete user foo
Creating Objects:
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
kubectl create deployment nginx --image=nginx # start a single instance of nginx
kubectl explain pods,svc # get the documentation for pod and svc manifests
# Create multiple YAML objects from stdin
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Pod
metadata:
name: busybox-sleep
spec:
containers:
- name: busybox
image: busybox
args:
- sleep
- "1000000"
---
apiVersion: v1
kind: Pod
metadata:
name: busybox-sleep-less
spec:
containers:
- name: busybox
image: busybox
args:
- sleep
- "1000"
EOF
# Create a secret with several keys
cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Secret
metadata:
name: mysecret
type: Opaque
data:
password: $(echo -n "s33msi4" | base64 -w0)
username: $(echo -n "jane" | base64 -w0)
EOFViewing, Finding Resources:
# Get commands with basic output
kubectl get services # List all services in the namespace
kubectl get pods --all-namespaces # List all pods in all namespaces
kubectl get pods -o wide # List all pods in the namespace, with more details
kubectl get deployment my-dep # List a particular deployment
kubectl get pods # List all pods in the namespace
kubectl get pod my-pod -o yaml # Get a pod's YAML
kubectl get pod my-pod -o yaml --export # Get a pod's YAML without cluster specific information
# Describe commands with verbose output
kubectl describe nodes my-node
kubectl describe pods my-pod
# List Services Sorted by Name
kubectl get services --sort-by=.metadata.name
# List pods Sorted by Restart Count
kubectl get pods --sort-by='.status.containerStatuses[0].restartCount'
# List PersistentVolumes sorted by capacity
kubectl get pv --sort-by=.spec.capacity.storage
# Get the version label of all pods with label app=cassandra
kubectl get pods --selector=app=cassandra -o \
jsonpath='{.items[*].metadata.labels.version}'
# Get all worker nodes (use a selector to exclude results that have a label
# named 'node-role.kubernetes.io/master')
kubectl get node --selector='!node-role.kubernetes.io/master'
# Get all running pods in the namespace
kubectl get pods --field-selector=status.phase=Running
# Get ExternalIPs of all nodes
kubectl get nodes -o jsonpath='{.items[*].status.addresses[?(@.type=="ExternalIP")].address}'
# List Names of Pods that belong to Particular RC
# "jq" command useful for transformations that are too complex for jsonpath, it can be found at https://stedolan.github.io/jq/
sel=${$(kubectl get rc my-rc --output=json | jq -j '.spec.selector | to_entries | .[] | "\(.key)=\(.value),"')%?}
echo $(kubectl get pods --selector=$sel --output=jsonpath={.items..metadata.name})
# Show labels for all pods (or any other Kubernetes object that supports labelling)
kubectl get pods --show-labels
# Check which nodes are ready
JSONPATH='{range .items[*]}{@.metadata.name}:{range @.status.conditions[*]}{@.type}={@.status};{end}{end}' \
&& kubectl get nodes -o jsonpath="$JSONPATH" | grep "Ready=True"
# List all Secrets currently in use by a pod
kubectl get pods -o json | jq '.items[].spec.containers[].env[]?.valueFrom.secretKeyRef.name' | grep -v null | sort | uniq
# List Events sorted by timestamp
kubectl get events --sort-by=.metadata.creationTimestampUpdating 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
# deprecated starting version 1.11
kubectl rolling-update frontend-v1 -f frontend-v2.json # (deprecated) Rolling update pods of frontend-v1
kubectl rolling-update frontend-v1 frontend-v2 --image=image:v2 # (deprecated) Change the name of the resource and update the image
kubectl rolling-update frontend --image=image:v2 # (deprecated) Update the pods image of frontend
kubectl rolling-update frontend-v1 frontend-v2 --rollback # (deprecated) Abort existing rollout in progress
cat pod.json | kubectl replace -f - # Replace a pod based on the JSON passed into std
# Force replace, delete and then re-create the resource. Will cause a service outage.
kubectl replace --force -f ./pod.json
# Create a service for a replicated nginx, which serves on port 80 and connects to the containers on port 8000
kubectl expose rc nginx --port=80 --target-port=8000
# Update a single-container pod's image version (tag) to v4
kubectl get pod mypod -o yaml | sed 's/\(image: myimage\):.*$/\1:v4/' | kubectl replace -f -
kubectl label pods my-pod new-label=awesome # Add 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" } }]'Editing Resources:
kubectl edit svc/docker-registry # Edit the service named docker-registry
KUBE_EDITOR="nano" kubectl edit svc/docker-registry # Use an alternative editorScaling 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 controllersDeleting Resources:
kubectl delete -f ./pod.json # Delete a pod using the type and name specified in pod.json
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 podInteracting with running Pods:
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)
kubectl run -i --tty busybox --image=busybox -- sh # Run pod as interactive shell
kubectl run nginx --image=nginx --restart=Never -n
mynamespace # Run pod nginx in a specific namespace
kubectl run nginx --image=nginx --restart=Never # Run pod nginx and write its spec into a file called pod.yaml
--dry-run -o yaml > pod.yaml
kubectl attach my-pod -i # Attach to Running Container
kubectl port-forward my-pod 5000:6000 # Listen on port 5000 on the local machine and forward to port 6000 on my-pod
kubectl exec my-pod -- ls / # Run command in existing pod (1 container case)
kubectl exec my-pod -c my-container -- ls / # Run command in existing pod (multi-container case)
kubectl top pod POD_NAME --containers # Show metrics for a given pod and its containersInteracting 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
# If a taint with that key and effect already exists, its value is replaced as specified.
kubectl taint nodes foo dedicated=special-user:NoScheduleResource 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 (just 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 groupFormatting output:
| 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 |
Kubectl output verbosity and debugging:
| 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=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. |