k8s 搭建nginx实例（serviceconfigmap和deployment组合）

Posted 2020-12-20 落烨无痕

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环境：k8s v1.18.5

网络环境： calico，通过nodePort方式对外提供nginx服务

一、创建nginx的service

1.定义nginx的service（nginx-service.yml）

apiVersion: v1
kind: Service
metadata:
  name: nginx-service  #定义service名称为nginx-service
  labels:
    app: nginx-service   #为service打上app标签
spec:
  type: NodePort   #使用NodePort方式开通，在每个Node上分配一个端口作为外部访问入口
  selector:
    app: my-nginx
  ports:
  - port: 8000  #port是k8s集群内部访问service的端口，即通过clusterIP: port可以访问到某个service
    targetPort: 80  #targetPort是pod的端口，从port和nodePort来的流量经过kube-proxy流入到后端pod的targetPort上，最后进入容器
    nodePort: 32500  #nodePort是外部访问k8s集群中service的端口，通过nodeIP: nodePort可以从外部访问到某个service

端口type类型：

• ClusterIP：默认，分配一个集群内部可以访问的虚拟IP（VIP）
• NodePort：在每个Node上分配一个端口作为外部访问入口
• LoadBalancer：工作在特定的Cloud Provider上，例如Google Cloud，AWS，OpenStack

2.创建nginx-service服务

kubectl create -f nginx-service.yml

3.验证服务是否创建成功

kubectl get svc

二、创建ngixn的configmap配置文件(nginx-configmap.yml)

1.定义nginx的configmap配置

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-configmap
data:
  nginx_conf: |-
    #user  nobody;
    worker_processes  1;
    events {
        worker_connections  1024;
    }
    http {
        include       mime.types;
        default_type  application/octet-stream;
        sendfile        on;
        keepalive_timeout  65;
        server {
            listen       80;
            server_name  localhost;
            location / {
                root   html;
                index  index.html index.htm;
            }
            error_page   500 502 503 504  /50x.html;
            location = /50x.html {
                root   html;
            }
        }
    }

2.创建nginx-configmap

kubectl create -f nginx-configmap.yml

3.验证是否创建成功

kubectl get cm

三、创建nginx的deployment

1.定义nginx的deployment

apiVersion: apps/v1
kind: Deployment
metadata:
  name: my-nginx
spec:
  selector:
    matchLabels:
      app: my-nginx
  replicas: 2
  template:
    metadata:
      labels:
        app: my-nginx
    spec:
      containers:
      - name: my-nginx
        image: nginx
        ports:
        - containerPort: 80
        volumeMounts:
          - mountPath: /etc/nginx/nginx.conf
            name: nginx
            subPath: nginx.conf
      volumes:
        - name: nginx
          configMap:
            name: nginx-configmap
            items:
              - key: nginx_conf
                path: nginx.conf
        #resources:
        #  requests:
        #    cpu: 1
        #    memory: 500Mi
        #  limits:
        #    cpu: 2
        #    memory: 1024Mi

2.创建nginx的deployment

kubectl create -f nginx-deployment.yml

3.验证deployment是否创建成功

kubectl get deploy

my-nginx就是创建的deploy，但是ready状态是0，证明pod为能成功创建。后面排查发现，pod一直卡在了容器创建阶段

4.验证deployment对应的pod是否创建成功

kubectl get pod

容器一直卡在容器创建阶段，需排查问题。

通过查看某个容器的详细信息，发现是nginx的configmap的问题：

kubectl describe pod my-nginx-65b859bc7b-qvh2t

Events:
Type Reason Age From Message
---- ------ ---- ---- -------
Normal Scheduled 10m default-scheduler Successfully assigned default/my-nginx-546db9c8f7-wxtzl to k8s-slave1
Normal SandboxChanged 8m34s (x3 over 8m41s) kubelet, k8s-slave1 Pod sandbox changed, it will be killed and re-created.
Normal Pulling 6m36s (x3 over 10m) kubelet, k8s-slave1 Pulling image "nginx"
Warning Failed 5m20s (x3 over 8m41s) kubelet, k8s-slave1 Failed to pull image "nginx": rpc error: code = Unknown desc = context canceled
Warning Failed 5m20s (x3 over 8m41s) kubelet, k8s-slave1 Error: ErrImagePull
Warning Failed 4m44s (x7 over 8m38s) kubelet, k8s-slave1 Error: ImagePullBackOff
Normal BackOff 2s (x14 over 8m38s) kubelet, k8s-slave1 Back-off pulling image "nginx"

原因：拉取nginx的镜像失败

解决方法：手动通过docker pull nginx 拉一次镜像下来。若手动拉取也一直卡住，则尝试重启node节点主机（因为我是在虚拟机上搭建的，所以可以随意重启，哈哈）

5.验证nginx是否正常提供服务

5.1 通过nodePort（节点机ip）访问

http://192.168.152.13:32500，出来了nginx 404页面，证明nginx是正常提供服务的。只是页面静态文件路径没有配置正确而已。