面向 Docker 用户的 kubectl

您可以使用 Kubernetes 命令行工具 kubectl 与 API Server 进行交互。如果您熟悉 Docker 命令行工具，使用 kubectl 会很简单。然而，Docker 命令和 kubectl 命令之间有一些区别。以下部分展示了 Docker 子命令并描述了等效的 kubectl 命令。

docker run

要运行一个 Nginx Deployment 并将其暴露，请参阅 kubectl create deployment。

Docker

docker run -d --restart=always -e DOMAIN=cluster --name nginx-app -p 80:80 nginx

55c103fa129692154a7652490236fee9be47d70a8dd562281ae7d2f9a339a6db

docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
55c103fa1296        nginx               "nginx -g 'daemon of…"   9 seconds ago       Up 9 seconds        0.0.0.0:80->80/tcp   nginx-app

kubectl

# start the pod running nginx
kubectl create deployment --image=nginx nginx-app

deployment.apps/nginx-app created

# add env to nginx-app
kubectl set env deployment/nginx-app  DOMAIN=cluster

deployment.apps/nginx-app env updated

# expose a port through with a service
kubectl expose deployment nginx-app --port=80 --name=nginx-http

service "nginx-http" exposed

通过使用 kubectl，您可以创建一个 Deployment，以确保 N 个 Pod 运行 Nginx，其中 N 是 Spec 中声明的副本数，默认为 1。您还可以创建一个带有与 Pod 标签匹配的选择器的 service。更多信息，请参阅 使用 Service 访问集群中的应用。

默认情况下，镜像在后台运行，类似于 docker run -d ...。要在前台运行，请使用 kubectl run 创建 Pod

kubectl run [-i] [--tty] --attach <name> --image=<image>

与 docker run ... 不同，如果您指定 --attach，则会附加到 stdin、stdout 和 stderr。您无法控制附加哪些流（docker -a ...）。要从容器中分离，可以键入转义序列 Ctrl+P，然后键入 Ctrl+Q。

docker ps

要列出当前正在运行的内容，请参阅 kubectl get。

Docker

docker ps -a

CONTAINER ID        IMAGE               COMMAND                  CREATED              STATUS                     PORTS                NAMES
14636241935f        ubuntu:16.04        "echo test"              5 seconds ago        Exited (0) 5 seconds ago                        cocky_fermi
55c103fa1296        nginx               "nginx -g 'daemon of…"   About a minute ago   Up About a minute          0.0.0.0:80->80/tcp   nginx-app

kubectl

kubectl get po

NAME                        READY     STATUS      RESTARTS   AGE
nginx-app-8df569cb7-4gd89   1/1       Running     0          3m
ubuntu                      0/1       Completed   0          20s

docker attach

要附加到容器中已经在运行的进程，请参阅 kubectl attach。

Docker

docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
55c103fa1296        nginx               "nginx -g 'daemon of…"   5 minutes ago       Up 5 minutes        0.0.0.0:80->80/tcp   nginx-app

docker attach 55c103fa1296
...

kubectl

kubectl get pods

NAME              READY     STATUS    RESTARTS   AGE
nginx-app-5jyvm   1/1       Running   0          10m

kubectl attach -it nginx-app-5jyvm
...

要从容器中分离，可以键入转义序列 Ctrl+P，然后键入 Ctrl+Q。

docker exec

要在容器中执行命令，请参阅 kubectl exec。

Docker

docker ps

CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                NAMES
55c103fa1296        nginx               "nginx -g 'daemon of…"   6 minutes ago       Up 6 minutes        0.0.0.0:80->80/tcp   nginx-app

docker exec 55c103fa1296 cat /etc/hostname

55c103fa1296

kubectl

kubectl get po

NAME              READY     STATUS    RESTARTS   AGE
nginx-app-5jyvm   1/1       Running   0          10m

kubectl exec nginx-app-5jyvm -- cat /etc/hostname

nginx-app-5jyvm

用于使用交互式命令。

Docker

docker exec -ti 55c103fa1296 /bin/sh
# exit

kubectl

kubectl exec -ti nginx-app-5jyvm -- /bin/sh
# exit

更多信息，请参阅 获取运行中容器的 Shell。

docker logs

要跟踪正在运行的进程的 stdout/stderr，请参阅 kubectl logs。

Docker

docker logs -f a9e

192.168.9.1 - - [14/Jul/2015:01:04:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.35.0" "-"
192.168.9.1 - - [14/Jul/2015:01:04:03 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.35.0" "-"

kubectl

kubectl logs -f nginx-app-zibvs

10.240.63.110 - - [14/Jul/2015:01:09:01 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"
10.240.63.110 - - [14/Jul/2015:01:09:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"

Pod 和容器之间存在细微差异；默认情况下，如果 Pod 中的进程退出，Pod 不会终止。相反，Pod 会重新启动进程。这类似于 Docker 的 --restart=always 选项，但有一个主要区别。在 Docker 中，进程的每次调用的输出是连接在一起的，但在 Kubernetes 中，每次调用是分开的。要在 Kubernetes 中查看上次运行的输出，请执行此操作

kubectl logs --previous nginx-app-zibvs

10.240.63.110 - - [14/Jul/2015:01:09:01 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"
10.240.63.110 - - [14/Jul/2015:01:09:02 +0000] "GET / HTTP/1.1" 200 612 "-" "curl/7.26.0" "-"

更多信息，请参阅 日志架构。

docker stop 和 docker rm

要停止并删除正在运行的进程，请参阅 kubectl delete。

Docker

docker ps

CONTAINER ID        IMAGE               COMMAND                CREATED             STATUS              PORTS                         NAMES
a9ec34d98787        nginx               "nginx -g 'daemon of"  22 hours ago        Up 22 hours         0.0.0.0:80->80/tcp, 443/tcp   nginx-app

docker stop a9ec34d98787

a9ec34d98787

docker rm a9ec34d98787

a9ec34d98787

kubectl

kubectl get deployment nginx-app

NAME         READY   UP-TO-DATE   AVAILABLE   AGE
nginx-app    1/1     1            1           2m

kubectl get po -l app=nginx-app

NAME                         READY     STATUS    RESTARTS   AGE
nginx-app-2883164633-aklf7   1/1       Running   0          2m

kubectl delete deployment nginx-app

deployment "nginx-app" deleted

kubectl get po -l app=nginx-app
# Return nothing

docker login

kubectl 中没有直接对应 docker login 的命令。如果您有兴趣将 Kubernetes 与私有镜像仓库一起使用，请参阅 使用私有镜像仓库。

docker version

要获取客户端和服务器的版本，请参阅 kubectl version。

Docker

docker version

Client version: 1.7.0
Client API version: 1.19
Go version (client): go1.4.2
Git commit (client): 0baf609
OS/Arch (client): linux/amd64
Server version: 1.7.0
Server API version: 1.19
Go version (server): go1.4.2
Git commit (server): 0baf609
OS/Arch (server): linux/amd64

kubectl

kubectl version

Client Version: version.Info{Major:"1", Minor:"6", GitVersion:"v1.6.9+a3d1dfa6f4335", GitCommit:"9b77fed11a9843ce3780f70dd251e92901c43072", GitTreeState:"dirty", BuildDate:"2017-08-29T20:32:58Z", OpenPaasKubernetesVersion:"v1.03.02", GoVersion:"go1.7.5", Compiler:"gc", Platform:"linux/amd64"}
Server Version: version.Info{Major:"1", Minor:"6", GitVersion:"v1.6.9+a3d1dfa6f4335", GitCommit:"9b77fed11a9843ce3780f70dd251e92901c43072", GitTreeState:"dirty", BuildDate:"2017-08-29T20:32:58Z", OpenPaasKubernetesVersion:"v1.03.02", GoVersion:"go1.7.5", Compiler:"gc", Platform:"linux/amd64"}

docker info

要获取有关环境和配置的杂项信息，请参阅 kubectl cluster-info。

Docker

docker info

Containers: 40
Images: 168
Storage Driver: aufs
 Root Dir: /usr/local/google/docker/aufs
 Backing Filesystem: extfs
 Dirs: 248
 Dirperm1 Supported: false
Execution Driver: native-0.2
Logging Driver: json-file
Kernel Version: 3.13.0-53-generic
Operating System: Ubuntu 14.04.2 LTS
CPUs: 12
Total Memory: 31.32 GiB
Name: k8s-is-fun.mtv.corp.google.com
ID: ADUV:GCYR:B3VJ:HMPO:LNPQ:KD5S:YKFQ:76VN:IANZ:7TFV:ZBF4:BYJO
WARNING: No swap limit support

kubectl

kubectl cluster-info

Kubernetes master is running at https://203.0.113.141
KubeDNS is running at https://203.0.113.141/api/v1/namespaces/kube-system/services/kube-dns/proxy
kubernetes-dashboard is running at https://203.0.113.141/api/v1/namespaces/kube-system/services/kubernetes-dashboard/proxy
Grafana is running at https://203.0.113.141/api/v1/namespaces/kube-system/services/monitoring-grafana/proxy
Heapster is running at https://203.0.113.141/api/v1/namespaces/kube-system/services/monitoring-heapster/proxy
InfluxDB is running at https://203.0.113.141/api/v1/namespaces/kube-system/services/monitoring-influxdb/proxy