kubectl
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[!NOTE] references:
info:
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/$(uname | awk '{print tolower($0)}')/amd64/kubectl
$ chmod +x ./kubectl
$ sudo mv ./kubectl /usr/local/bin/kubectl
# verify
$ kubectl version --client --short
Flag --short has been deprecated, and will be removed in the future. The --short output will become the default.
Client Version: v1.25.3
Kustomize Version: v4.5.
kubectl-convert
[!NOTE] A plugin for Kubernetes command-line tool kubectl, which allows you to convert manifests between different API versions. This can be particularly helpful to migrate manifests to a non-deprecated api version with newer Kubernetes release.
# intel
$ curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/darwin/amd64/kubectl-convert"
# apple silicon
$ curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/darwin/arm64/kubectl-convert"
$ chmod +x ./kubectl-convert
$ sudo mv ./kubectl-convert /usr/local/bin/kubectl-convert
$ sudo chown root: /usr/local/bin/kubectl-convert
sha256 check
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/$(uname | awk '{print tolower($0)}')/amd64/kubectl
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/$(uname | awk '{print tolower($0)}')/amd64/kubectl.sha256
$ echo "$(cat kubectl.sha256) kubectl" | shasum -a 256 --check
# intel
$ curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/darwin/amd64/kubectl"
# apple silicon
$ curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/darwin/arm64/kubectl"
# or via brew
$ brew install kubectl
completion
[!NOTE] The Homebrew installation of bash-completion v2 sources all the files in the
BASH_COMPLETION_COMPAT_DIR
directory, that's why the latter two methods work
$ brew install bash-completion # Bash 3.2
$ brew install bash-completion@2 # Bash 4.1+
$ kubectl completion bash > $(brew --prefix)/etc/bash_completion.d/kubectl
$ curl -LO https://storage.googleapis.com/kubernetes-release/release/`curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt`/bin/$(uname | awk '{print tolower($0)}')/amd64/kubectl
$ chmod +x ./kubectl
$ sudo mv ./kubectl /usr/local/bin/kubectl
completion
$ echo 'source <(kubectl completion bash)' >> ~/.bash_profile
$ kubectl completion bash > /usr/local/etc/bash_completion.d/kubectl
$ echo 'alias k=kubectl' >> ~/.bash_profile
$ echo 'complete -o default -F __start_kubectl k' >> ~/.bash_profile
> choco install kubernetes-cli
> cd %USERPROFILE%
> mkdir .kube
> touch .kube/config
$ kubectl get all -A
$ kubectl get cs
NAME STATUS MESSAGE ERROR
controller-manager Healthy ok
scheduler Healthy ok
etcd-1 Healthy {"health":"true"}
etcd-2 Healthy {"health":"true"}
etcd-0 Healthy {"health":"true"}
name
$ kubectl -n devops get po -o custom-columns='NAME:metadata.name'
or
$ kubectl -n devops get deploy jenkins -o custom-columns="NAME:metadata.name, IMAGES:..image"
NAME IMAGES
jenkins jenkins/jenkins:2.187
$ kubectl get pod -o=custom-columns=NAME:.metadata.name,STATUS:.status.phase,NODE:.spec.nodeName \
--all-namespaces
sort pods by nodeName
$ kubectl get pods -o wide --sort-by="{.spec.nodeName}"
sort by restart count
sort by age
$ kubectl get pods --all-namespaces \
-o jsonpath="{..image}" |
tr -s '[[:space:]]' '\n' |
sort |
uniq -c
$ kubectl -n devops get deployment jenkins -o=jsonpath='{.spec.template.spec.containers[:1].image}'
jenkins/jenkins:2.187
or
$ kubectl -n devops get deploy jenkins -o jsonpath="{..image}"
jenkins/jenkins:2.187
$ kubectl get pods --all-namespaces -o=jsonpath="{..image}" -l app=nginx
$ kubectl -n <namespace> get po \
-o custom-columns='NAME:metadata.name,IMAGES:spec.containers[*].image'
$ kubectl -n <namespace> get po <pod_name> -o jsonpath="{..containerID}"
# or
$ kubectl -n <namespace> get po <pod_name> \
-o go-template \
--template="{{ range .status.containerStatuses }}{{ .containerID }}{{end}}"
$ kubectl get pods --all-namespaces -o jsonpath="{.items[*].spec.containers[*].image}"
or
$ kubectl get pods --all-namespaces -o jsonpath="{..image}" |
tr -s '[[:space:]]' '\n' |
sort |
uniq -c
$ kubectl -n kube-system get pods -o jsonpath="{..image}"
$ kubectl get po --all-namespaces \
-o go-template \
--template="{{range .items}}{{range .spec.containers}}{{.image}} {{end}}{{end}}"
$ kubectl get deploy \
-o=jsonpath="{range .items[*]}{'\n'}{.metadata.name}{':\t'}{range .spec.template.spec.containers[*]}{.image}{', '}{end}{end}"
$ for _i in $(kubectl get ns --no-headers | awk -F' ' '{print $1}'); do
echo ------------- ${_i} ------------
kubectl -n ${_i} describe quota
done
$ kubectl get apiservice
delete apiservers
$ kubectl delete apiservice v1beta1.metrics.k8s.io
$ kubectl get --raw=/apis
check available
$ kubectl api-resources
$ kubectl api-versions
check apiservices registered
$ kubectl get apiservices.apiregistration.k8s.io
$ kubectl get apiservices.apiregistration.k8s.io v1beta1.metrics.k8s.io -o yaml
$ kubectl get apiservices.apiregistration.k8s.io
NAME SERVICE AVAILABLE AGE
v1. Local True 4y
v1.apps Local True 4y
v1.authentication.k8s.io Local True 4y
v1.authorization.k8s.io Local True 4y
v1.autoscaling Local True 4y
v1.batch Local True 4y
v1.monitoring.coreos.com Local True 168d
v1.networking.k8s.io Local True 4y
v1.rbac.authorization.k8s.io Local True 4y
v1.storage.k8s.io Local True 4y
v1beta1.admissionregistration.k8s.io Local True 4y
v1beta1.apiextensions.k8s.io Local True 4y
v1beta1.apps Local True 4y
v1beta1.authentication.k8s.io Local True 4y
v1beta1.authorization.k8s.io Local True 4y
v1beta1.batch Local True 4y
v1beta1.certificates.k8s.io Local True 4y
v1beta1.coordination.k8s.io Local True 4y
v1beta1.events.k8s.io Local True 4y
v1beta1.extensions Local True 4y
v1beta1.metrics.k8s.io kube-system/metrics-server False (ServiceNotFound) 188d
v1beta1.policy Local True 4y
v1beta1.rbac.authorization.k8s.io Local True 4y
v1beta1.scheduling.k8s.io Local True 4y
v1beta1.storage.k8s.io Local True 4y
v1beta2.apps Local True 4y
v2beta1.autoscaling Local True 4y
v2beta2.autoscaling Local True 4y0
$ kubectl get apiservices.apiregistration.k8s.io v1beta1.metrics.k8s.io -o yaml --export
apiVersion: apiregistration.k8s.io/v1
kind: APIService
metadata:
name: v1beta1.metrics.k8s.io
spec:
group: metrics.k8s.io
groupPriorityMinimum: 100
insecureSkipTLSVerify: true
service:
name: prometheus-adapter
namespace: monitoring
version: v1beta1
versionPriority: 100
status:
conditions:
- lastTransitionTime: 2022-08-15T14:10:39Z
message: all checks passed
reason: Passed
status: "True"
type: Available
troubleshooting
[!NOTE|label:references:]
$ kubectl api-resources error: unable to retrieve the complete list of server APIs: metrics.k8s.io/v1beta1: the server is currently unable to handle the request
references:
$ kubectl get --raw=/healthz/etcd
ok
[!NOTE|label:references:]
$ kubectl patch deploy dev-jenkins -n devops-ci \
--type='json' \
-p='[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value": "jenkins/jenkins:2.461-jdk17"}]'
[!TIP]
jsonpath vs. json patch path
{.spec.template.spec.containers[0].image} → /spec/template/spec/containers/0/image
$ kubectl -n devops-ci get deployment dev-jenkins -o json |
jq -r 'paths(scalars) as $p | select(getpath($p) | tostring | test(".*jenkins.*")) |
"/"+($p | map(tostring) | join("/")) + " = " + (getpath($p) | tostring)'
/metadata/labels/app = dev-jenkins
/metadata/name = dev-jenkins
/metadata/selfLink = /apis/extensions/v1beta1/namespaces/devops-ci/deployments/dev-jenkins
/spec/selector/matchLabels/app = dev-jenkins
/spec/template/metadata/labels/app = dev-jenkins
/spec/template/spec/containers/0/env/0/value = -Duser.timezone='America/Los_Angeles' -Dhudson.model.DirectoryBrowserSupport.CSP="" -Djenkins.slaves.NioChannelSelector.disabled=true -Djenkins.slaves.JnlpSlaveAgentProtocol3.enabled=false -Djava.awt.headless=true -Djenkins.security.ClassFilterImpl.SUPPRESS_WHITELIST=true -Dhudson.model.ParametersAction.keepUndefinedParameters=true -Dcom.cloudbees.workflow.rest.external.ChangeSetExt.resolveCommitAuthors=true -Djenkins.install.runSetupWizard=true -Dpermissive-script-security.enabled=true -DsessionTimeout=1440 -DsessionEviction=43200 -Dfile.encoding=UTF-8 -Dsun.jnu.encoding=utf-8 -Dgroovy.grape.report.downloads=true -Divy.message.logger.level=4 -Dhudson.plugins.active_directory.ActiveDirectorySecurityRealm.forceLdaps=false -Djenkins.model.Jenkins.logStartupPerformance=true -Dhudson.security.csrf.DefaultCrumbIssuer.EXCLUDE_SESSION_ID=true -Djsch.client_pubkey='ssh-rsa,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256' -Djsch.server_host_key='ssh-rsa,ssh-ed25519,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,rsa-sha2-512,rsa-sha2-256' -Xms32g -Xmx32g -XX:+AlwaysPreTouch -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/var/jenkins_home/logs -XX:+UseG1GC -XX:+UseStringDeduplication -XX:+ParallelRefProcEnabled -XX:+DisableExplicitGC -XX:+UnlockDiagnosticVMOptions -XX:+UnlockExperimentalVMOptions -verbose:gc -XX:+PrintGC -XX:+PrintGCDetails -XX:ErrorFile=/var/jenkins_home/logs/hs_err_%p.log -XX:+LogVMOutput -XX:LogFile=/var/jenkins_home/logs/jvm.log -XX:InitialRAMPercentage=50.0 -XX:MaxRAMPercentage=50.0 -Xlog:gc*=info,gc+heap=debug,gc+ref*=debug,gc+ergo*=trace,gc+age*=trace:file=/var/jenkins_home/logs/gc-%t.log:utctime,pid,level,tags:filecount=2,filesize=100M
/spec/template/spec/containers/0/env/1/value = -Dorg.jenkinsci.remoting.engine.JnlpProtocol3.disabled=false
/spec/template/spec/containers/0/image = artifactory.marvell.com/it-devops-dockerub-remote/jenkins/jenkins:2.512-jdk21
/spec/template/spec/containers/0/name = dev-jenkins
/spec/template/spec/containers/0/volumeMounts/0/mountPath = /var/jenkins_home
/spec/template/spec/containers/0/volumeMounts/0/name = dev-jenkins-home
/spec/template/spec/serviceAccount = dev-jenkins-admin
/spec/template/spec/serviceAccountName = dev-jenkins-admin
/spec/template/spec/volumes/0/name = dev-jenkins-home
/spec/template/spec/volumes/0/persistentVolumeClaim/claimName = dev-jenkins-pvc
/status/conditions/0/message = ReplicaSet "dev-jenkins-569fcd784c" has successfully progressed.
PURPOSE
JSON PATCH PATH
JSONPATH EXPRESSION
Used for
Modifying fields in kubectl patch --type=json
Reading/querying values in kubectl get -o jsonpath=...
Syntax
Slash-separated path (/a/b/0/c
)
Dot notation with array indexing ({.a.b[0].c}
)
Array access
Index with /0/
Index with [0]
Wildcards / filters
Not supported
Supported
FIELD
JSON PATCH PATH
JSONPATH EXPRESSION
Container image
/spec/template/spec/containers/0/image
{.spec.template.spec.containers[0].image}
Container name
/spec/template/spec/containers/0/name
{.spec.template.spec.containers[0].name}
[!NOTE|label:referenecs]
oneline cmd
$ cat << EOF | kubectl create -f -
apiVersion: v1
kind: Secret
metadata:
name: mysecret
type: Opaque
data:
password: $(echo "admin" | base64)
username: $(echo "1f2d1e2e67df" | base64)
EOF
# Edit the last-applied-configuration annotations by type/name in YAML
kubectl apply edit-last-applied deployment/nginx
# Edit the last-applied-configuration annotations by file in JSON
kubectl apply edit-last-applied -f deploy.yaml -o json
[!NOTE|label:references:] -** How do you rollback deployments in Kubernetes?
# format
$ kubectl rollout undo deployment <name> --to-revision=<n>
# -- i.e.: --
# rollout to specific version ( 3 )
$ kubectl -n devops-ci rollout undo deployment/devops-dev-jenkins --to-revision=3
# -- check rollout status --
$ kubectl -n devops-ci rollout status deployment/devops-dev-jenkins
# or
$ kubectl -n devops-ci get deploy devops-dev-jenkins -o jsonpath='{.spec.template.spec.containers[*].image}'
$ kubectl -n devops-ci rollout history deployment/dev-jenkins
deployment.extensions/dev-jenkins
REVISION CHANGE-CAUSE
...
48 <none>
49 <none>
$ kubectl -n devops-ci get replicasets -l app=dev-jenkins --sort-by=.metadata.creationTimestamp
NAME DESIRED CURRENT READY AGE
...
dev-jenkins-f6846c86d 0 0 0 31d
dev-jenkins-569fcd784c 1 1 1 5h21m
# with --record
$ kubectl -n devops-ci set image deployment/dev-jenkins dev-jenkins=artifactory.marvell.com/it-devops-dockerub-remote/jenkins/jenkins:2.512-jdk21 --record
Flag --record has been deprecated, --record will be removed in the future
deployment.extensions/dev-jenkins image updated
$ kubectl -n devops-ci rollout history deployment/dev-jenkins
deployment.extensions/dev-jenkins
REVISION CHANGE-CAUSE
...
48 <none>
49 kubectl set image deployment/dev-jenkins dev-jenkins=artifactory.marvell.com/it-devops-dockerub-remote/jenkins/jenkins:2.512-jdk21 --kubeconfig=/Users/marslo/iMarslo/job/devops/env/linux/dc5-ssdfw8/.kube/config --namespace=devops-ci --record=tru
# with annotate
# -- update --
$ kubectl -n devops-ci set image deployment/dev-jenkins dev-jenkins=artifactory.marvell.com/it-devops-dockerub-remote/jenkins/jenkins:2.512-jdk21 --record
# -- annotate --
$ kubectl -n devops-ci annotate deployment dev-jenkins kubernetes.io/change-cause="Upgrade Jenkins to 2.512-jdk21 @ $(date +'%F %T')"
$ kubectl -n devops-ci rollout history deployment/dev-jenkins
$ kubectl -n devops-ci rollout history deployment/dev-jenkins
deployment.extensions/dev-jenkins
REVISION CHANGE-CAUSE
...
48 <none>
49 upgrade dev jenkins to 2.512-jdk21 @ 2025-06-02 20:45:16
$ kubectl -n devops-ci get rs -l app=dev-jenkins \
-o jsonpath='{range .items[*]}{"REV: "}{.metadata.annotations.deployment\.kubernetes\.io/revision}{" CAUSE: "}{.metadata.annotations.kubernetes\.io/change-cause}{"\n"}{end}'
Warning: short name "rs" could also match lower priority resource replicasets.apps
REV: 49 CAUSE: upgrade dev jenkins to 2.512-jdk21 @ 2025-06-02 20:45:16
REV: 44 CAUSE:
...
# or
$ kubectl -n devops-ci rollout history deployment/dev-jenkins
deployment.extensions/dev-jenkins
REVISION CHANGE-CAUSE
...
48 <none>
49 upgrade dev jenkins to 2.512-jdk21 @ 2025-06-02 20:45:16
$ kubectl -n devops-ci get replicasets -l app=dev-jenkins --sort-by=.metadata.creationTimestamp
NAME DESIRED CURRENT READY AGE
...
dev-jenkins-f6846c86d 0 0 0 31d
dev-jenkins-569fcd784c 1 1 1 5h30m
# show timestamp
$ kubectl -n devops-ci get replicasets -l app=devops-dev-jenkins \
-o=jsonpath='{range .items[*]}{"REVISION: "}{.metadata.annotations.deployment\.kubernetes\.io/revision}{"\tCREATED: "}{.metadata.creationTimestamp}{"\n"}{end}' |
sort
...
REVISION: 48 CREATED: 2025-05-02T23:36:56Z
REVISION: 49 CREATED: 2025-06-02T22:19:17Z
$ uname | awk '{print tolower($0)}'
darwin
$ curl -s https://storage.googleapis.com/kubernetes-release/release/stable.txt
v1.26.2
$ kubectl get pods --sort-by="{.status.containerStatuses[:1].restartCount}"
$ kubectl get replicasets -o wide --sort-by=.metadata.creationTimestamp
$ kubectl get pods --sort-by=.status.startTime
$ kubectl get pods --field-selector=status.phase=Pending \
--sort-by=.metadata.creationTimestamp |
awk 'match($5,/^[1-5]d/) {print $0}'
$ kubectl get apiservices.apiregistration.k8s.io
NAME SERVICE AVAILABLE AGE
v1beta1.metrics.k8s.io kube-system/metrics-server False (ServiceNotFound) 188d
# remove metrics.k8s.io
$ kubectl delete apiservices.apiregistration.k8s.io v1beta1.metrics.k8s.io
# debug
$ kubectl get secrets $(kubectl -n kube-system get sa metrics-server -o 'jsonpath={.secrets[].name}')
Error from server (NotFound): secrets "metrics-server-token-mr49q" not found
$ kubectl get secrets $(kubectl -n kube-system get sa metrics-server -o 'jsonpath={.secrets[].name}') \
-o "jsonpath={.data.ca\.crt}" |
base64 -d |
openssl x509 -text -noout |
grep Not
# get token
$ kubectl get secrets $(kubectl -n kube-system get sa metrics-server -o 'jsonpath={.secrets[].name}') \
-o "jsonpath={.data.token}" |
base64 -d -w0
# get namespace
$ kubectl get secrets $(kubectl -n kube-system get sa metrics-server -o 'jsonpath={.secrets[].name}') \
-o "jsonpath={.data.namespace}" |
base64 -d -w0
Field quoting or escaping
Follows RFC 6902 JSON Patch rules
Follows JSONPath syntax rules