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Kubectl-CLI

Kubectl 자동 완성​

BASH​

source <(kubectl completion bash) # bash-completion 패키지를 먼저 설치한 후, bash의 자동 완성을 현재 셸에 설정한다
echo "source <(kubectl completion bash)" >> ~/.bashrc # 자동 완성을 bash 셸에 영구적으로 추가한다

ZSH​

source <(kubectl completion zsh)  # 현재 셸에 zsh의 자동 완성 설정
echo "[[ $commands[kubectl] ]] && source <(kubectl completion zsh)" >> ~/.zshrc # 자동 완성을 zsh 셸에 영구적으로 추가한다.

Basic​

kubectl create​

deployment

## Usage
kubectl create deployment NAME --image=image -- [COMMAND] [args...]

## Create a deployment named my-dep that runs the nginx image with 3 replicas
kubectl create deployment my-dep --image=nginx --replicas=3

## Create a deployment named my-dep that runs the busybox image and expose port 5701
kubectl create deployment my-dep --image=busybox --port=5701

namespace

## Usage
kubectl create namespace NAME [--dry-run=server|client|none]

## Create a new namespace named my-namespace
kubectl create namespace my-namespace

kubectl get​

간단한 정보를 확인할 수 있다

## 네임스페이스 내 모든 파드의 목록 조회
kubectl get pods
kubectl get po

## 라벨과 함께 파드 목록 조회
kubectl get pods --show-labels

## 모든 네임스페이스 내 모든 파드의 목록 조회
kubectl get pods --all-namespaces

## kube-system 네임스페이스 내 모든 파드의 목록 조회
kubectl get pod -n kube-system

## 해당하는 네임스페이스 내 모든 파드의 상세 목록 조회
kubectl get pods -o wide

## 네임스페이스 내 모든 서비스의 목록 조회
kubectl get services
kubectl get svc

kubectl get pod --all-namespaces

kubectl run​

Usage

$ kubectl run NAME --image=image [--env="key=value"] [--port=port] [--dry-run=server|client] [--overrides=inline-json] [--command] -- [COMMAND] [args...]
## Start a hazelcast pod and let the container expose port 5701
kubectl run hazelcast --image=hazelcast/hazelcast --port=5701

## Dry run; print the corresponding API objects without creating them
kubectl run nginx --image=nginx --dry-run=client

## Start the nginx pod using the default command, but use custom arguments (arg1 .. argN) for that command
kubectl run nginx --image=nginx -- <arg1> <arg2> ... <argN>

## Start the nginx pod using a different command and custom arguments
kubectl run nginx --image=nginx --command -- <cmd> <arg1> ... <argN

kubectl expose​

Usage

$ kubectl expose (-f FILENAME | TYPE NAME) [--port=port] [--protocol=TCP|UDP|SCTP] [--target-port=number-or-name] [--name=name] [--external-ip=external-ip-of-service] [--type=type]
kubectl expose deployment http-go --port=8080 --target-port=8080 --type=LoadBalancer

## Create a service for a pod valid-pod, which serves on port 444 with the name "frontend"
kubectl expose pod valid-pod --port=444 --name=frontend

## Create a service for a replicated nginx using replica set, which serves on port 80 and connects to the containers on port 8000
kubectl expose rs nginx --port=80 --target-port=8000

## Create a service for an nginx deployment, which serves on port 80 and connects to the containers on port 8000
kubectl expose deployment nginx --port=80 --target-port=8000

kubectl delete​

## webapp pod 삭제
kubectl delete pod webapp

## name=myLabel 라벨을 가진 파드와 서비스 삭제
kubectl delete pods,services -l name=myLabel

## deployment.yaml과 service.yaml 설정 파일을 사용하여 리소스 삭제
kubectl delete -f deployment.yaml -f service.yaml

## "production" 네임스페이스 삭제 (네임스페이스 삭제 시 네임스페이스에 존재하는 모든 리소스 또한 삭제된다)
kubectl delete namespace production

APP Management​

kubectl apply​

apply는 쿠버네티스 리소스를 정의하는 파일을 통해 애플리케이션을 관리한다. kubectl apply를 실행하여 클러스터에 리소스를 생성하고 업데이트한다. 이것은 프로덕션 환경에서 쿠버네티스 애플리케이션을 관리할 때 권장된다.

  • 쿠버네티스 매니페스트는 JSON이나 YAML로 정의된다.
  • 파일 확장자는 .yaml , .yml, .json 이 사용된다.
## 리소스 생성
kubectl apply -f ./my-manifest.yaml

kubectl edit​

kubectl edit pod redis

kubectl label​

## new-label=awesome 라벨 추가
kubectl label pods my-pod new-label=awesome

## new-label=awesome 라벨 삭제
kubectl label pods my-pod new-label-

kubectl rollout​

## 완료될 때까지 "frontend" 디플로이먼트의 롤링 업데이트 상태를 감시
kubectl rollout status -w deployment/frontend   

## 이전 디플로이먼트로 롤백
kubectl rollout undo deployment/frontend

## 현 리비전을 포함한 디플로이먼트의 이력을 체크
kubectl rollout history deployment/frontendkubectl rollout history deployment/first-app --revision=1

## 특정 리비전으로 롤백
kubectl rollout undo deployment/frontend --to-revision=2

kubectl scale​

## 'foo'라는 레플리카셋을 3으로 스케일
kubectl scale --replicas=3 rs/foo

## 'foo'라는 deployment를 1으로 스케일
kubectl scale --replicas=1 deployment foo

## "foo.yaml"에 지정된 리소스의 크기를 3으로 스케일
kubectl scale --replicas=3 -f foo.yaml

kubectl set​

## "frontend" 디플로이먼트의 "www" 컨테이너 이미지를 업데이트하는 롤링 업데이트
kubectl set image deployment/frontend www=image:v2

## "my-nginx-depolyment" deployment의 "nginx"라는 이름을 가지는 컨테이너의 이미지를 "nginx:1.11"로 변경
kubectl set image deployment my-nginx-deployment nginx=nginx:1.11 --record

## Update deployment 'registry' with a new environment variable
kubectl set env deployment/registry STORAGE_DIR=/local

Working with apps​

kubectl describe​

생성된 리소스의 자세한 정보를 확인할 수 있다

## my-nginx-pod의 자세한 정보 조회하기
kubectl describe pods my-nginx-pod

kubectl exec​

Usage

$ kubectl exec (POD | TYPE/NAME) [-c CONTAINER] [flags] -- COMMAND [args...]
## Get output from running the 'date' command from pod mypod, using the first container by default
kubectl exec mypod -- date

## Get output from running the 'date' command in ruby-container from pod mypod
kubectl exec mypod -c ruby-container -- date

## Switch to raw terminal mode; sends stdin to 'bash' in ruby-container from pod mypod # and sends stdout/stderr from 'bash' back to the client
kubectl exec mypod -c ruby-container -i -t -- bash -il

## 동작 중인 컨테이너의 셸 접근
kubectl exec --stdin --tty shell-demo -- /bin/bash

kubectl logs​

Usage

$ kubectl logs [-f] [-p] (POD | TYPE/NAME) [-c CONTAINER]
## 파드 로그 덤프 (stdout)
kubectl logs my-pod

## 이전 켄테이너 로그 확인
kubectl logs my-pod --previous

## Return snapshot logs from pod nginx with multi containers
kubectl logs nginx --all-containers=true

## Begin streaming the logs of the ruby container in pod web-1
kubectl logs -f -c ruby web-1

## Display only the most recent 20 lines of output in pod nginx
kubectl logs --tail=20 nginx

## Show all logs from pod nginx written in the last hour
kubectl logs --since=1h nginx

Flags

NameShorthandDefaultUsage
all-containersfalseGet all containers' logs in the pod(s).
containercPrint the logs of this container
followffalseSpecify if the logs should be streamed.
ignore-errorsfalseIf watching / following pod logs, allow for any errors that occur to be non-fatal
insecure-skip-tls-verify-backendfalseSkip verifying the identity of the kubelet that logs are requested from. In theory, an attacker could provide invalid log content back. You might want to use this if your kubelet serving certificates have expired.
limit-bytes0Maximum bytes of logs to return. Defaults to no limit.
max-log-requests5Specify maximum number of concurrent logs to follow when using by a selector. Defaults to 5.
pod-running-timeout20sThe length of time (like 5s, 2m, or 3h, higher than zero) to wait until at least one pod is running
prefixfalsePrefix each log line with the log source (pod name and container name)
previouspfalseIf true, print the logs for the previous instance of the container in a pod if it exists.
selectorlSelector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2). Matching objects must satisfy all of the specified label constraints.
since0sOnly return logs newer than a relative duration like 5s, 2m, or 3h. Defaults to all logs. Only one of since-time / since may be used.
since-timeOnly return logs after a specific date (RFC3339). Defaults to all logs. Only one of since-time / since may be used.
tail-1Lines of recent log file to display. Defaults to -1 with no selector, showing all log lines otherwise 10, if a selector is provided.
timestampsfalseInclude timestamps on each line in the log output

kubectl top​

  • Display resource (CPU/memory) usage of nodes.
  • The top-node command allows you to see the resource consumption of nodes.
kubectl top node
## Show metrics for all pods in the default namespace 
kubectl top pod

Cluster Management​

kubectl cordon​

  • Mark node as unschedulable.

Usage

$ kubectl cordon NODE

kubectl drain​

  • 레퍼런스
  • 노드를 비우고 노드를 unschedulable로 표시한다.

Usage

$ kubectl drain NODE
#Drain node "foo", even if there are pods not managed by a replication controller, replica set, job, daemon set or stateful set on it
kubectl drain foo --force

#As above, but abort if there are pods not managed by a replication controller, replica set, job, daemon set or stateful set, and use a grace period of 15 minutes
kubectl drain foo --grace-period=900

Flags

NameShorthandDefaultUsage
chunk-size500Return large lists in chunks rather than all at once. Pass 0 to disable. This flag is beta and may change in the future.
delete-emptydir-datafalseContinue even if there are pods using emptyDir (local data that will be deleted when the node is drained).
delete-local-datafalseContinue even if there are pods using emptyDir (local data that will be deleted when the node is drained).
disable-evictionfalseForce drain to use delete, even if eviction is supported. This will bypass checking PodDisruptionBudgets, use with caution.
dry-runnoneMust be "none", "server", or "client". If client strategy, only print the object that would be sent, without sending it. If server strategy, submit server-side request without persisting the resource.
forcefalseContinue even if there are pods that do not declare a controller.
grace-period-1Period of time in seconds given to each pod to terminate gracefully. If negative, the default value specified in the pod will be used.
ignore-daemonsetsfalseIgnore DaemonSet-managed pods.
pod-selectorLabel selector to filter pods on the node
selectorlSelector (label query) to filter on, supports '=', '==', and '!='.(e.g. -l key1=value1,key2=value2). Matching objects must satisfy all of the specified label constraints.
skip-wait-for-delete-timeout0If pod DeletionTimestamp older than N seconds, skip waiting for the pod. Seconds must be greater than 0 to skip.
timeout0sThe length of time to wait before giving up, zero means infinite

kubectl taint​

Usage

$ kubectl taint NODE NAME KEY_1=VAL_1:TAINT_EFFECT_1 ... KEY_N=VAL_N:TAINT_EFFECT_N
#Update node 'foo' with a taint with key 'dedicated' and value 'special-user' and effect 'NoSchedule' # If a taint with that key and effect already exists, its value is replaced as specified
kubectl taint nodes foo dedicated=special-user:NoSchedule

## remove from node 'foo' the taint with key 'dedicated' and effect 'NoSchedule' if one exists
kubectl taint nodes foo dedicated:NoSchedule-

kubectl uncordon​

  • Mark node as schedulable.

Usage

$ kubectl uncordon NODE

KUBECTL SETTINGS AND USAGE​

kubectl explain​

USAGE

kubectl explain RESOURCE
#Get the documentation of the resource and its fields
$kubectl explain pods
KIND:     Pod
VERSION:  v1

DESCRIPTION:
     Pod is a collection of containers that can run on a host. This resource is
     created by clients and scheduled onto hosts.

FIELDS:
   apiVersion	<string>
     APIVersion defines the versioned schema of this representation of an
     object. Servers should convert recognized schemas to the latest internal
     value, and may reject unrecognized values. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#resources

   kind	<string>
     Kind is a string value representing the REST resource this object
     represents. Servers may infer this from the endpoint the client submits
     requests to. Cannot be updated. In CamelCase. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#types-kinds

   metadata	<Object>
     Standard object's metadata. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#metadata

   spec	<Object>
     Specification of the desired behavior of the pod. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status

   status	<Object>
     Most recently observed status of the pod. This data may not be up to date.
     Populated by the system. Read-only. More info:
     https://git.k8s.io/community/contributors/devel/sig-architecture/api-conventions.md#spec-and-status
     
## Get the documentation of a specific field of a resource
kubectl explain pods.spec.containers

참고