Skip to content

Latest commit

 

History

History
264 lines (180 loc) · 7.54 KB

kubectl_tips.md

File metadata and controls

264 lines (180 loc) · 7.54 KB
Raw

Kubectl Tips

Install

  • linux
    • latest version
      • curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
    • specific version, say, 1.23.0
      • curl -LO https://dl.k8s.io/release/v1.23.0/bin/linux/amd64/kubectl
  • macos:
    • replace linux with darwin
chmod +x ./kubectl
mv ./kubectl /usr/local/bin/kubectl

kubectl cheatsheet

cheatsheet

list pod names

$ kubectl get pods -A  -o go-template --template '{{range .items}}{{.metadata.name}}{{"\n"}}{{end}}'
ingress-nginx-admission-create-gfm2j
ingress-nginx-admission-patch-dmmj2
ingress-nginx-controller-86b6d5756c-mgp5v

OR

# --no-headers to remove column name
$ kubectl get po -A  --no-headers -o custom-columns=:.metadata.name
ingress-nginx-admission-create-gfm2j
ingress-nginx-admission-patch-dmmj2
ingress-nginx-controller-86b6d5756c-mgp5v

List Detailed Info -o wide

$ kubectl get po -A -o wide
NAMESPACE       NAME            READY   STATUS      RESTARTS   AGE  IP          NODE    NOMINATED NODE   READINESS GATES
ingress-nginx   ingress-....    0/1     Completed   0          8h   10.244.0.6  node1   <none>           <none>

print annotations information

$ kubectl get ingress payquick-ingress-443  -o jsonpath='{.metadata.annotations.qcloud_cert_id}'
yIhaisHO

what if the key of annotation has special character like "/" , "." ?

$ kubectl get ingress payquick-ingress-443  -o go-template='{{index .metadata.annotations "kubernetes.io/ingress.qcloud-loadbalance-id"}}'
lb-9l23xjd5

print yaml file

# get yaml 
kubectl ... get ...  -o yaml --export

full service name across namespaces

# full service name across namespaces
<service-name>.<namespace-name>.svc.cluster.local

Specify a Context

# list all context
kubectl config get-contexts

# specify context
kubectl_tke --context=<ContextName>  get nodes

rollout/restart deployment

kubectl -n <namespace> rollout restart deployment <deployment-name>

查找不是 running 状态的 pod

$ kubectl get pods --all-namespaces | awk '{ if ($4!="Running")  print $0_ }'
NAMESPACE            NAME                                           READY   STATUS      RESTARTS   AGE
ingress-nginx        ingress-nginx-admission-create-gfm2j           0/1     Completed   0          9h

JSONPath 表达式

# 选择一个列表的指定元素
$ kubectl get pods -o custom-columns='DATA:spec.containers[0].image'
DATA
hashicorp/http-echo

# 选择和一个过滤表达式匹配的列表元素
$ kubectl get pods -o custom-columns='DATA:spec.containers[?(@.image!="nginx")].image'

# 选择特定位置下的所有字段（无论名称是什么）
$ kubectl get pods -o custom-columns='DATA:metadata.*'

# 选择具有特定名称的所有字段（无论其位置如何）
$ kubectl get pods -o custom-columns='DATA:..image'

显示 Pod 的所有容器镜像:

$ kubectl get pods -o custom-columns='NAME:metadata.name,IMAGES:spec.containers[*].image'
NAME                                           IMAGES
apple-app                                      hashicorp/http-echo

显示节点的可用区域:

$ kubectl get nodes -o custom-columns='NAME:metadata.name,ZONE:metadata.labels.failure-domain\.beta\.kubernetes\.io/zone'
  • 每个节点的可用区都可以通过标签failure-domain.beta.kubernetes.io/zone来获得
  • 如果你的 Kubernetes 集群部署在公有云上面（比如 AWS、Azure 或 GCP），那么上面的命令就非常有用了

Deleting Namespace "stuck" as Terminating, how to solve it ?

kubectl get namespace "stucked-namespace" -o json \
  | tr -d "\n" | sed "s/\"finalizers\": \[[^]]\+\]/\"finalizers\": []/" \
  | kubectl replace --raw /api/v1/namespaces/stucked-namespace/finalize -f -

Run Image with specific command to test purpose

$ kubectl [-n <namespace>] run <pod-name>  --image=<image-path> --command -- <command [args]>

Advanced Skill

Search log in all pods, even from .gz file 
NAMESPACE="your-namespace"
SELECTOR="k8s-app=xxxxxxx"
TEXT="GET /callback"

yesterday=`python -c 'import datetime;import time; print datetime.datetime.utcfromtimestamp( time.time() - 3600*24*0 ).strftime("%Y%m%d")'`
tdbyesterday=`python -c 'import datetime;import time; print datetime.datetime.utcfromtimestamp( time.time() - 3600*24*1 ).strftime("%Y%m%d")'`


if [ "$1" != ""  ]
then
    TEXT=$1
fi

for pod in `kubectl -n $NAMESPACE get po --no-headers --selector=$SELECTOR  -o custom-columns='NAME:metadata.name'`
do
    echo -------------- seaching $pod
    # archived gz file by logrotate
    echo "\t" , app.log-$yesterday.gz
    kubectl -n $NAMESPACE exec -it $pod -- gunzip -k -c logs/app.log-$yesterday.gz   | grep "$TEXT"
    echo "\t" , app.log-$tdbyesterday.gz
    kubectl -n $NAMESPACE exec -it $pod -- gunzip -k -c logs/app.log-$tdbyesterday.gz   | grep "$TEXT"
    echo "\t" , app.log
    kubectl -n $NAMESPACE exec -it $pod -- cat logs/app.log   | grep "$TEXT"
done
postStart / preStop event handle

Define postStart and preStop handlers

on TKE, add it on deployment yaml, following the image property.

example: when this pod restart , before it really ready, make 1 another service/pod relanuch.

        lifecycle:
          postStart:
            exec:
              command: ["/bin/sh", "-c", "_NS=co-hse-dev && _APP=co-hse-app  && replinum=`kubectl -n $_NS get deploy $_APP -o=jsonpath='{.status.replicas}'` && kubectl -n $_NS  scale  deployments/$_APP --replicas=$(($replinum-1)) && kubectl -n $_NS  scale  deployments/$_APP --replicas=$replinum"]