Kubernetes
minikube 安装
https://minikube.sigs.k8s.io/docs/start/
以 ubuntu 22 为例
创建 docker 用户并安装 docker
sudo useradd -m -s /bin/bash docker
sudo passwd docker
sudo usermod -aG sudo docker
安装 docker
https://docs.docker.com/engine/install/ubuntu/
# Add Docker's official GPG key:
sudo apt-get update
sudo apt-get install ca-certificates curl
sudo install -m 0755 -d /etc/apt/keyrings
sudo curl -fsSL https://download.docker.com/linux/ubuntu/gpg -o /etc/apt/keyrings/docker.asc
sudo chmod a+r /etc/apt/keyrings/docker.asc
# Add the repository to Apt sources:
echo \
"deb [arch=$(dpkg --print-architecture) signed-by=/etc/apt/keyrings/docker.asc] https://download.docker.com/linux/ubuntu \
$(. /etc/os-release && echo "$VERSION_CODENAME") stable" | \
sudo tee /etc/apt/sources.list.d/docker.list > /dev/null
sudo apt-get update
# Install Docker
sudo apt-get install docker-ce docker-ce-cli containerd.io docker-buildx-plugin docker-compose-plugin
# Verify Installation
sudo docker run hello-world
curl -LO https://github.com/kubernetes/minikube/releases/latest/download/minikube-linux-amd64
sudo install minikube-linux-amd64 /usr/local/bin/minikube && rm minikube-linux-amd64
启动和停止
minikube start
minikube stop
安装 kubectl
https://kubernetes.io/docs/tasks/tools/install-kubectl-linux/
curl -LO "https://dl.k8s.io/release/$(curl -L -s https://dl.k8s.io/release/stable.txt)/bin/linux/amd64/kubectl"
sudo install -o root -g root -m 0755 kubectl /usr/local/bin/kubectl
kubectl version --client
Client Version: v1.32.1
Kustomize Version: v5.5.0
查看节点
kubectl get nodes
NAME STATUS ROLES AGE VERSION
minikube Ready control-plane 127m v1.32.0
查看服务
kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 128m
查看 pod
kubectl get po -A
NAMESPACE NAME READY STATUS RESTARTS AGE
kube-system coredns-668d6bf9bc-bwj9m 1/1 Running 0 56s
kube-system etcd-minikube 1/1 Running 0 61s
kube-system kube-apiserver-minikube 1/1 Running 0 61s
kube-system kube-controller-manager-minikube 1/1 Running 0 61s
kube-system kube-proxy-cmmfw 1/1 Running 0 56s
kube-system kube-scheduler-minikube 1/1 Running 0 62s
kube-system storage-provisioner 1/1 Running 1 (26s ago) 59s
apiVersion: apps/v1
apiVersion: apps/v1
kind: Deployment
metadata:
name: nginx
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- name: nginx
image: nginx:1.26
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: nginx
spec:
selector:
app: nginx
ports:
- protocol: TCP
port: 80
targetPort: 80
nodePort: 10000
type: NodePort
secret
docker@GreenCloud:~$ echo '1234' > pass.txt
docker@GreenCloud:~$ kubectl create secret generic pass --from-file=pass.txt
secret/pass created
docker@GreenCloud:~$ kubectl get secrets
NAME TYPE DATA AGE
pass Opaque 1 7s
Pod 与容器
kubernetes 中最小的调度单元。
常见使用方式有 2 中：运行单个容器的 pod 和运行多个协同容器的 pod
但通常不会直接管理 pod ，而是通过 deployment 和 job 等负载管理，如果要跟踪状态则用 statefulSet
查询 pod
# 查询 pod （默认命名空间）
kubectl get po|pod|pods
# 查询所有命名空间
kubectl get pod -A
# 查询详细信息
kubectl get pod -o wide
# 监控状态
kubectl get pod -w
# 指定命名空间
kubectl get pod -n kube-system
# 查看帮助
kubectl get pod --help
手动创建一个 pod
kubectl run mynginx --image=nginx:1.27.3
查看详细信息
kubectl describe pod mynginx
便携 mynginx.yml 文件
# api 版本
apiVersion: v1
# 类型
kind: Pod
# 元数据
metadata:
name: mynginx
spec:
containers:
- name: nginx
image: nginx:1.27.3
ports:
- containerPort: 80
通过 yml 文件创建 pod ，使用 kubectl create/apply 命令， create 只能创建一次，apply 不存在会创建，存在则更新
$ kubectl apply -f nginx-pod.yml
pod/mynginx created
删除 pod
kubectl delete pod mynginx
kubectl delete -f nginx-pod.yml
进入 pod 的容器
kubectl exec -it <pod name> -c <container name> -- <command>
# 不指定容器则进入 pod 的第一个容器
kubectl exec -it mynginx -- /bin/bash
查看日志
kubectl logs -f mynginx
创建包含多个容器的 pod
apiVersion: v1
kind: Pod
metadata:
name: nginx-redis
labels:
env: dev
name: nginx-redis
spec:
containers:
- name: nginx
image: nginx:1.27.3
ports:
- containerPort: 80
- name: redis
image: redis:7.4
ports:
- containerPort: 6379
查看 pod
$ kubectl get pod
NAME READY STATUS RESTARTS AGE
nginx-redis 2/2 Running 0 7s
查看日志
# redis 容器日志
kubectl logs -f nginx-redis -c redis
# nginx 容器日志
kubectl logs -f nginx-redis -c nginx
标签
标签的值为 0-63 个字符，支持大小写，数字，下划线，横岗，点，需要以字母开头
可以在刚才的 yml 文件中添加自定义标签
apiVersion: v1
kind: Pod
metadata:
name: nginx-redis
labels:
env: dev
name: nginx-redis
查看 pod
$ kubectl get po --show-labels
NAME READY STATUS RESTARTS AGE LABELS
nginx-redis 2/2 Running 0 11s env=dev,name=nginx-redis
Pod 的生命周期
起始 Pending，正常启动 Running ，成功或失败结束的 Succeed Faild ，unknown 位置状态，通常是与节点通信失败
容器的生命周期：Waiting 仍然没有完全启动， Running 正在运行，且 postStart 回调已经执行， Terminated 已终止且 preStop 已经执行
apiVersion: v1
kind: Pod
metadata:
name: life
spec:
containers:
- name: nginx
image: nginx:1.27.3
lifecycle:
postStart:
exec:
command: ["/bin/sh", "-c", "echo postStart >> /start.txt"]
preStop:
exec:
command: ["/bin/sh", "-c", "echo preStop >> /stop.txt && sleep 50"]
ports:
- containerPort: 80
重启策略
通过 spec.restartPolicy 字段配置重启策略，适用于所有容器。Always 总是重启， OnFailure 异常退出状态非 0 时重启，Nerver 不重启，默认 Always
创建一个 pod 用于测试
apiVersion: v1
kind: Pod
metadata:
name: policy
spec:
containers:
- name: nginx
image: nginx:1.27.3
restartPolicy: Always
查看容器。另外打开一个 terminal ，进入容器并停止 nginx -s stop，可以看到一个 pod 重新启动
$ kubectl get po -w
NAME READY STATUS RESTARTS AGE
policy 1/1 Running 0 10s
policy 0/1 Completed 0 45s
policy 1/1 Running 1 (2s ago) 47s
如果设为 Never ，可以观察到
$ kubectl get po -w
NAME READY STATUS RESTARTS AGE
policy 1/1 Running 0 1s
policy 0/1 Completed 0 17s
policy 0/1 Completed 0 18s
传递启动参数
Kubernetes 可以通过 command 和 args 来修改容器启动默认命令和传递参数
开启 redis 容器的持久化，使用 redis-server --appendonly yes 作为启动命令
apiVersion: v1
kind: Pod
metadata:
name: redis-command
spec:
containers:
- name: redis
image: redis:7.4
command: ["redis-server"]
args: ["--appendonly yes"]
验证
$ kubectl exec -it redis-command -- ls
appendonlydir
资源限制
可以对 cpu 和内存进行资源限制，有 2 种限制：request 可以使用的基础资源， limit 可以使用的最大资源，超过最大资源会被 kill
apiVersion: v1
kind: Pod
metadata:
name: nginx-limit
spec:
containers:
- name: nginx
image: nginx:1.27.3
resources:
requests:
memory: "100Mi"
cpu: "500m"
limits:
memory: "200Mi"
cpu: "1"
Init 容器
在 pod 内容器启动之前运行，进行一些前置操作。如果 Init 容器失败，kubernetes 会不断重启知道成功为止。
apiVersion: v1
kind: Pod
metadata:
name: testinit
spec:
containers:
- name: init
image: busybox:1.36
command: ["sh", "-c", "echo the app is running! && sleep 3600"]
imagePullPolicy: IfNotPresent
initContainers:
- name: init-service
image: busybox:1.36
command: ["sh", "-c", "echo init service is running && sleep 5"]
- name: init-db
image: busybox:1.36
command: ["sh", "-c", "echo init db is running && sleep 5"]
运行
$ kubectl apply -f testinit.yml
pod/testinit created
$ kubectl get po -w
NAME READY STATUS RESTARTS AGE
testinit 0/1 Init:1/2 0 7s
testinit 0/1 Init:1/2 0 7s
testinit 0/1 PodInitializing 0 12s
testinit 1/1 Running 0 13s
$ kubectl describe pod testinit
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 83s default-scheduler Successfully assigned default/testinit to minikube
Normal Pulled 83s kubelet Container image "busybox:1.36" already present on machine
Normal Created 83s kubelet Created container: init-service
Normal Started 83s kubelet Started container init-service
Normal Pulled 77s kubelet Container image "busybox:1.36" already present on machine
Normal Created 77s kubelet Created container: init-db
Normal Started 77s kubelet Started container init-db
Normal Pulled 71s kubelet Container image "busybox:1.36" already present on machine
Normal Created 71s kubelet Created container: init
Normal Started 71s kubelet Started container init
Controller
控制器监控集群的状态，并致力于将当前状态转变为期望的状态
常见的 Controller ：Deployment, Job, Daemonset, StatefulSet
Deployment 最常用的 Controller
Daemonset 最多只运行一个 pod 副本的场景
Statefulset pod 的名称在整个生命周期不变，保证副本按照顺序启动，更新，删除
Job 运行结束就删除
Controller 通过 label 关联 pod