1. 什么是 kubectl
kubectl 是 Kubernetes 的命令行工具，通过 API server 与集群进行交互。
2. 配置 kubectl
kubectl 可以通过 ~/.kube/config 配置连接到一个或多个集群。具体如何配置可以参考: 配置对多集群的访问 。如果需要配置远程集群，可以参考: 搭建远程 Kubernetes 开发环境。查看配置的集群:
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kubectl config get-contexts
CURRENT NAME CLUSTER AUTHINFO NAMESPACE
* minikube minikube minikube
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选择某个集群:
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kubectl config set-context minikube
Context "minikube" modified.
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3. kubectl 命令
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kubectl
kubectl controls the Kubernetes cluster manager.
Find more information at: https://kubernetes.io/docs/reference/kubectl/overview/
Basic Commands (Beginner):
create Create a resource from a file or from stdin.
expose Take a replication controller, service, deployment or pod and expose it as a new Kubernetes Service
run Run a particular image on the cluster
set Set specific features on objects
run-container Run a particular image on the cluster. This command is deprecated, use "run" instead
Basic Commands (Intermediate):
get Display one or many resources
explain Documentation of resources
edit Edit a resource on the server
delete Delete resources by filenames, stdin, resources and names, or by resources and label selector
Deploy Commands:
rollout Manage the rollout of a resource
rolling-update Perform a rolling update of the given ReplicationController
scale Set a new size for a Deployment, ReplicaSet, Replication Controller, or Job
autoscale Auto-scale a Deployment, ReplicaSet, or ReplicationController
Cluster Management Commands:
certificate Modify certificate resources.
cluster-info Display cluster info
top Display Resource (CPU/Memory/Storage) usage.
cordon Mark node as unschedulable
uncordon Mark node as schedulable
drain Drain node in preparation for maintenance
taint Update the taints on one or more nodes
Troubleshooting and Debugging Commands:
describe Show details of a specific resource or group of resources
logs Print the logs for a container in a pod
attach Attach to a running container
exec Execute a command in a container
port-forward Forward one or more local ports to a pod
proxy Run a proxy to the Kubernetes API server
cp Copy files and directories to and from containers.
auth Inspect authorization
Advanced Commands:
apply Apply a configuration to a resource by filename or stdin
patch Update field(s) of a resource using strategic merge patch
replace Replace a resource by filename or stdin
convert Convert config files between different API versions
Settings Commands:
label Update the labels on a resource
annotate Update the annotations on a resource
completion Output shell completion code for the specified shell (bash or zsh)
Other Commands:
api-versions Print the supported API versions on the server, in the form of "group/version"
config Modify kubeconfig files
help Help about any command
plugin Runs a command-line plugin
version Print the client and server version information
Usage:
kubectl [flags] [options]
Use "kubectl <command> --help" for more information about a given command.
Use "kubectl options" for a list of global command-line options (applies to all commands).
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使用语法:
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kubectl [command] [TYPE] [NAME] [flags]
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- command，指定要对一个或多个资源执行的操作，例如
create、get、describe、delete。
- TYPE，指定资源类型。资源类型不区分大小写，可以指定单数、复数或缩写形式。例如:
kubectl get pod pod_name 。
- NAME，指定资源的名称。名称区分大小写。如果省略名称，则显示所有资源的详细信息。例如:
kubectl get pods 。
- flags，指定可选的参数。例如，可以使用 -s 或 -server 参数指定 Kubernetes API 服务器的地址和端口。
4. kubectl 部署 Jenkins
创建 Namespace ，隔离服务
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kubectl create namespace jenkins
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使用 Deployment 部署 Jenkins
新增 jenkins-deployment.yaml 文件。
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cat jenkins-deployment.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: jenkins-deployment
spec:
replicas: 1
selector:
matchLabels:
app: jenkins
template:
metadata:
labels:
app: jenkins
spec:
containers:
- name: jenkins
image: jenkins:2.60.3
ports:
- containerPort: 8080
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执行命令，部署 Deployment。
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kubectl create -f jenkins-deployment.yaml --namespace=jenkins
deployment.extensions/jenkins-deployment created
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查看相关信息
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kubectl describe deployments --namespace=jenkins
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创建 service 暴露服务
新增 jenkins-service.yaml 文件。
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cat jenkins-service.yaml
apiVersion: v1
kind: Service
metadata:
name: jenkins
spec:
type: NodePort
ports:
- port: 8080
targetPort: 8080
nodePort: 30000
selector:
app: jenkins
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执行命令，部署 service ，nodePort 参数指定对外的服务端口。
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kubectl create -f jenkins-service.yaml --namespace=jenkins
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访问服务
在浏览器打开链接: http://your_node_host_ip:30000 ，发现需要输入初始密码。
从日志获取访问初始密码
查看 Pod 名称:
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kubectl get pods --namespace=jenkins
NAME READY STATUS RESTARTS AGE
jenkins-deployment-868cc579df-42lpn 1/1 Running 0 21m
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获取密码:
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kubectl log jenkins-deployment-868cc579df-42lpn --namespace=jenkins
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在日志中，可以查看到初始化密码。
5. 重启 Kubernetes 中的 Job
以 CentOS 7 为例：
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yum install -y https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm
yum install -y jq
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kubectl get job
job_name
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kubectl get job job_name -o json | jq 'del(.spec.selector)' | jq 'del(.spec.template.metadata.labels)' | kubectl replace --force -f -
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6. 参考
- https://kubernetes.io/docs/reference/kubectl/overview/
- https://devopscube.com/setup-jenkins-on-kubernetes-cluster/
- https://serverfault.com/questions/809632/is-it-possible-to-rerun-kubernetes-job
