# get node status confditions
JSONPATH='{range .items[*]}{@.metadata.name}: {range @.status.conditions[*]}{@.type}={@.status}, {end}{"\n"}{end}' \
 && kubectl get nodes -o jsonpath="$JSONPATH"

# check node cpu / memory usage
kubectl top pod 

# check node status
kubectl describe nodes kubernetes-minion-emt8.c.myproject.internal

# find out the most hight cpu cost pod of a node
kubectl get po -A -owide | grep ${NODE_NAME} | awk '{print $1, $2}' | xargs -n2 kubectl top pod --no-headers -n $1 | sort --key 2 -nr | column -t

# find out the most hight memory cost pod of a node
kubectl get po -A -owide | grep ${NODE_NAME} | awk '{print $1, $2}' | xargs -n2 kubectl top pod --no-headers -n $1 | sort --key 3 -nr | column -t

# get resource sort by name
kubectl get services --sort-by=.metadata.name

# check pod cpu / memory usage
# all pod in current namespace
kubectl top pod 
# all pod and its containers in current namespace
kubectl top pod --containers
# this pod and its containers in current namespace
kubectl top pod nginx-0 --containers
# sort by cpu
kubectl top pod --sort-by=cpu --no-headers
# sort by memory
kubectl top pod --sort-by=memory --no-headers

# get pods which are not in Running
kubectl get pods --field-selector=status.phase!=Running

# get events for a certainer pod
kubectl get event --namespace default --field-selector involvedObject.name=nginx-0

kubectl rollout history deployment/nginx
kubectl rollout history statefulset/nginx

# get first pod log 
kubectl logs `kubectl get po -o name | grep keyword | head -1`
kubectl exec -it `kubectl get po -o name | grep keyword | head -1` -- bash

# get configmap item
kubectl get configmap nginx -o jsonpath='{.data.nginx\.conf}'

# 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 json | jq -c 'paths|join(".")'

# Produce a period-delimited tree of all keys returned for pods, etc
kubectl get pods -o json | jq -c 'paths|join(".")'

# View api resources list
kubectl api-resources
kubectl api-resources --sort-by=name 
kubectl api-resources --sort-by=kind

kubectl api-resources --api-group=networking.k8s.io

# check contaner statuses
kubectl get pod nginx-0 -n default -o jsonpath="{.status.containerStatuses}" | jq

# get events for a certainer pod
kubectl get event --namespace default --field-selector involvedObject.name=nginx-0

# run a mysql client pod to troubleshoot database issue:
kubectl run myclient --rm -i --tty --image mysql:5.7 -- bash

# run a postgres client pod to troubleshoot database issue:
kubectl run pgclient --rm -i --tty --image postgres:13-alpine -- bash

# run a mongo client pod to troubleshoot mongodb issue:
kubectl run mongoclient --rm -i --tty --image mongo:5 -- bash

# run a busybox pod to troubleshoot network or http issue
kubectl run debugger --rm -i --tty --image nicolaka/netshoot:latest -- bash

# run a netshoot pod to troubleshoot network or http issue
kubectl run debugger --rm -i --tty --image nicolaka/netshoot:latest -- bash

# disable healthcheck if you want to troubleshoot healthcheck failure
# --type json, use json patch(RFC 6902), check official docs
kubectl patch deployment nginx --type json -p='[{"op": "remove", "path": "/spec/template/spec/containers/0/livenessProbe"}]'

# increase initialDelaySeconds to 3600
kubectl patch deploy nginx --type json \
  -p='[{"op": "replace", "path": "/spec/template/spec/containers/0/livenessProbe/initialDelaySeconds", "value": 3600}]
      {"op": "replace", "path": "/spec/template/spec/containers/0/readinessProbe/initialDelaySeconds", "value": 3600}]'

# change "command" to "sleep 1000" to troubleshoot entrypoint command error
kubectl patch deployment nginx --type json -p='[{"op": "replace", "path": "/spec/template/spec/containers/0/command", "value":["sleep", "1000"]}]'

# change image to troubleshoot software version issue
kubectl patch deployment nginx --type='json' -p='[{"op": "replace", "path": "/spec/template/spec/containers/0/image", "value":"nginx:1.21"}]'

# or with set image sub cmd
kubectl set image deployment/nginx nginx=nginx:1.21 # {containerName}=${image}

# scale a deployment
kubectl scale --replicas=2 deploy/nginx
# scale a statefulset
kubectl scale --replicas=2 statefulset/nginx
# scale multiple deployments
kubectl scale --replicas=2 deploy/nginx1 deploy/nginx2 deploy/nginx3
# scale with kubctl patch
kubectl patch deploy nginx --patch '{"spec": {"replicas": 2}}'

# restart container inside your pod without chaging pod name and pod ip
kubectl exec -it nginx-0 -- /bin/sh -c "kill 1"

# run a test nginx deployment
kubectl create deployment nginx --image=nginx

# delete
kubectl delete deploy nginx

# run a test busybox deployment
kubectl create deployment busybox --image=busybox -- sleep 1000

# delete
kubectl delete deploy busybox 

# create nginx statefulset
export APP_NAME=nginx
export IMAGE=nginx:latest

cat <<EOF | kubectl apply -f -
apiVersion: v1
kind: Service
metadata:
  name: ${APP_NAME}
  labels:
    app: ${APP_NAME}
spec:
  ports:
  - port: 80
    name: web
  clusterIP: None
  selector:
    app: ${APP_NAME}
---
apiVersion: apps/v1
kind: StatefulSet
metadata:
  name: ${APP_NAME}
spec:
  serviceName: ${APP_NAME}
  replicas: 1
  selector:
    matchLabels:
      app: ${APP_NAME}
  template:
    metadata:
      labels:
        app: ${APP_NAME}
    spec:
      containers:
      - name: ${APP_NAME}
        image: ${IMAGE}
        ports:
        - containerPort: 80
          name: web
#         volumeMounts:
#         - name: www
#           mountPath: /usr/share/nginx/html
#   volumeClaimTemplates:
#   - metadata:
#       name: www
#     spec:
#       accessModes: [ "ReadWriteOnce" ]
#       resources:
#         requests:
#           storage: 1Gi
EOF

kubeval /tmp/a.yaml 
PASS - /tmp/a.yaml contains a valid Service (nginx)
PASS - /tmp/a.yaml contains a valid StatefulSet (nginx)