快速创建一个可访问的服务
快速创建一个可访问的服务
1 创建一个 k8s 集群
安装 Docker Desktop，并在设置中开启Kubernetes 功能 
这时，你会得到一个单节点的 k8s 集群
通过 kubectl get nodes 查看，会输出以下内容：
➜ qsk-book git:(main) ✗ kubectl get nodes
NAME STATUS ROLES AGE VERSION
docker-desktop Ready control-plane 14h v1.30.2
现在启动了一个名为 docker-desktop 的 control-plane （控制面） 节点
2 将应用部署到 k8s
下载示例文件（示例文件是《Kubernetes 快速入门》一书的附带内容）：
git clone https://github.com/nigelpoulton/qsk-book.git
cd qsk-book
ls -l
# 输出内容
total 24
drwxr-xr-x 7 wudanyang 224 10 13 15:50 App
drwxr-xr-x 8 wudanyang 256 10 13 15:50 Appv1.1
-rw-r--r-- 1 wudanyang 509 10 14 13:04 deploy.yml
-rw-r--r-- 1 wudanyang 225 10 13 15:50 pod.yml
-rw-r--r-- 1 wudanyang 929 10 13 15:50 readme.md
-rw-r--r-- 1 wudanyang 509 10 13 15:50 rolling-update.yml
-rw-r--r-- 1 wudanyang 178 10 13 15:50 svc-cloud.yml
-rw-r--r-- 1 wudanyang 217 10 13 15:50 svc-local.yml
部署 Pod：
kubectl apply -f pod.yml
➜ qsk-book git:(main) ✗ kubectl get pods
NAME READY STATUS RESTARTS AGE
first-pod 1/1 Running 0 6s
查看部署的 Pod
kubectl describe pod first-pod
可以看到，现在 Pod 是运行中了，端口号监听的是 8080
Name: first-pod
Namespace: default
Priority: 0
Service Account: default
Node: docker-desktop/192.168.65.3
Start Time: Mon, 14 Oct 2024 14:49:56 +0800
Labels: project=qsk-book
Annotations: <none>
Status: Running
IP: 10.1.0.27
IPs:
IP: 10.1.0.27
Containers:
web-ctr:
Container ID: docker://d06da3abd9e749933edc798a99571e3540bf8a16059823a78e4483530157e323
Image: nigelpoulton/qsk-book:latest
Image ID: docker-pullable://nigelpoulton/qsk-book@sha256:ea4422925917a5d957aab20603bbd2521e811088dc68ca3f5703458966733d72
Port: 8080/TCP
Host Port: 0/TCP
State: Running
Started: Mon, 14 Oct 2024 14:50:00 +0800
Ready: True
Restart Count: 0
Environment: <none>
Mounts:
/var/run/secrets/kubernetes.io/serviceaccount from kube-api-access-j8kn6 (ro)
Conditions:
Type Status
PodReadyToStartContainers True
Initialized True
Ready True
ContainersReady True
PodScheduled True
Volumes:
kube-api-access-j8kn6:
Type: Projected (a volume that contains injected data from multiple sources)
TokenExpirationSeconds: 3607
ConfigMapName: kube-root-ca.crt
ConfigMapOptional: <nil>
DownwardAPI: true
QoS Class: BestEffort
Node-Selectors: <none>
Tolerations: node.kubernetes.io/not-ready:NoExecute op=Exists for 300s
node.kubernetes.io/unreachable:NoExecute op=Exists for 300s
Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 16m default-scheduler Successfully assigned default/first-pod to docker-desktop
Normal Pulling 16m kubelet Pulling image "nigelpoulton/qsk-book:latest"
Normal Pulled 16m kubelet Successfully pulled image "nigelpoulton/qsk-book:latest" in 3.231s (3.231s including waiting). Image size: 193578060 bytes.
Normal Created 16m kubelet Created container web-ctr
Normal Started 16m kubelet Started container web-ctr
3 连接到应用
如果只是部署了一个应用，那么在外部是不能访问到这个应用的，因为它的网络只工作在 k8s 的内部
要想在外部访问应用，还得使用 Service 才行
使用 svc-local.yml 文件部署一个 Service 对象
➜ qsk-book git:(main) ✗ kubectl apply -f svc-local.yml
service/svc-local created
# 2022 version
apiVersion: v1
kind: Service
metadata:
name: svc-local
spec:
type: NodePort
ports:
- port: 8080
protocol: TCP
targetPort: 8080
nodePort: 31111
selector:
project: qsk-book
配置文件的内容大概意思就是将 label 为 project: qsk-book 的应用的8080 端口映射到节点的 31111 端口，细节再去看书
➜ qsk-book git:(main) ✗ kubectl get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
kubernetes ClusterIP 10.96.0.1 <none> 443/TCP 15h
svc-local NodePort 10.101.54.180 <none> 8080:31111/TCP 2m34s
出现下面的情况，就代表访问通了
4 清理应用
kubectl delete pod first-pod
5 应用自我修复
自我修复需要一个新的对象：Deployment
kubectl apply -f deploy.yml
- replicas 副本数 5 个
# 2022 version
apiVersion: apps/v1
kind: Deployment
metadata:
name: qsk-deploy
spec:
replicas: 5
selector:
matchLabels:
project: qsk-book
strategy:
type: RollingUpdate
rollingUpdate:
maxSurge: 1
maxUnavailable: 0
template:
metadata:
labels:
project: qsk-book
spec:
containers:
- name: qsk-pod
imagePullPolicy: Always
ports:
- containerPort: 8080
image: nigelpoulton/qsk-book:1.1
➜ qsk-book git:(main) ✗ kubectl get deploy
NAME READY UP-TO-DATE AVAILABLE AGE
qsk-deploy 5/5 5 5 4h5m
➜ qsk-book git:(main) ✗ kubectl get pods
NAME READY STATUS RESTARTS AGE
qsk-deploy-668c8bdb95-6cw5d 1/1 Running 0 141m
qsk-deploy-668c8bdb95-dgtx5 1/1 Running 0 140m
qsk-deploy-668c8bdb95-f97mk 1/1 Running 0 140m
qsk-deploy-668c8bdb95-qhzl4 1/1 Running 0 141m
qsk-deploy-668c8bdb95-xssrf 1/1 Running 0 141m
5.1 Pod 故障重新拉起
使用命令删除掉一个 pod，模拟有一个 pod 故障了
kubectl delete pod qsk-deploy-668c8bdb95-6cw5d
可以看到立刻有一个 pod 被创建
➜ qsk-book git:(main) ✗ kubectl get pods
NAME READY STATUS RESTARTS AGE
qsk-deploy-668c8bdb95-6cw5d 1/1 Terminating 0 143m
qsk-deploy-668c8bdb95-dgtx5 1/1 Running 0 141m
qsk-deploy-668c8bdb95-f97mk 1/1 Running 0 141m
qsk-deploy-668c8bdb95-qbhtg 0/1 ContainerCreating 0 3s
qsk-deploy-668c8bdb95-qhzl4 1/1 Running 0 142m
qsk-deploy-668c8bdb95-xssrf 1/1 Running 0 142m
5.2 工作节点故障重新部署
本地没有多节点环境，所以无法模拟
具体现象是，如果故障节点上面有 2 个 pod，那么这 2 个 pod 会被部署到仍存在的节点上
如果节点机器提供者也有故障恢复，那么故障的节点会重新加入到 k8s 集群中，但是已经被迁移走的 pod 不会重新回来
6 应用扩缩容
修改 deploy.yml 将 replicas 修改成你想要的数量
重新执行： kubectl apply -f deploy.yml
扩容时，会重新创建新 pod
➜ qsk-book git:(main) ✗ kubectl get pods
NAME READY STATUS RESTARTS AGE
qsk-deploy-668c8bdb95-dgtx5 1/1 Running 0 148m
qsk-deploy-668c8bdb95-f97mk 1/1 Running 0 149m
qsk-deploy-668c8bdb95-fxh4n 0/1 ContainerCreating 0 4s
qsk-deploy-668c8bdb95-hn5bq 0/1 ContainerCreating 0 4s
qsk-deploy-668c8bdb95-qbhtg 1/1 Running 0 7m8s
qsk-deploy-668c8bdb95-qhzl4 1/1 Running 0 149m
qsk-deploy-668c8bdb95-tj4wv 0/1 ContainerCreating 0 4s
qsk-deploy-668c8bdb95-xssrf 1/1 Running 0 149m
缩容时，会将多余的 pod 删掉（我发现都是删除的运行时间比较短的 pod）
➜ qsk-book git:(main) ✗ kubectl get pods
NAME READY STATUS RESTARTS AGE
qsk-deploy-668c8bdb95-dgtx5 1/1 Running 0 149m
qsk-deploy-668c8bdb95-f97mk 1/1 Terminating 0 149m
qsk-deploy-668c8bdb95-fxh4n 1/1 Terminating 0 48s
qsk-deploy-668c8bdb95-hn5bq 1/1 Terminating 0 48s
qsk-deploy-668c8bdb95-qbhtg 1/1 Terminating 0 7m52s
qsk-deploy-668c8bdb95-qhzl4 1/1 Running 0 150m
qsk-deploy-668c8bdb95-tj4wv 1/1 Terminating 0 48s
qsk-deploy-668c8bdb95-xssrf 1/1 Running 0 150m
7 应用滚动更新
kubectl apply -f rolling-update.yml
rolling-update.yml 和 原来的配置的区别：
执行之后，会新创建一个新的 Pod，将老的 pod 删掉
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