3.K8s必知必会

Kubernetes
容器化
发布日期:   2021-03-09
文章字数:   4.9k
阅读时长:   24 分
阅读次数:  

1 Controllers

官网：https://kubernetes.io/docs/concepts/workloads/controllers/

ReplicationController(RC)

官网：https://kubernetes.io/docs/concepts/workloads/controllers/replicationcontroller/

A ReplicationController ensures that a specified number of pod replicas are running at any one time. In other words, a ReplicationController makes sure that a pod or a homogeneous set of pods is always up and available.

ReplicationController定义了一个期望的场景，即声明某种Pod的副本数量在任意时刻都符合某个预期值，所以RC的定义包含以下几个部分：

  • Pod期待的副本数（replicas）
  • 用于筛选目标Pod的Label Selector
  • 当Pod的副本数量小于预期数量时，用于创建新Pod的Pod模板（template）

也就是说通过RC实现了集群中Pod的高可用，减少了传统IT环境中手工运维的工作。

Have a try

kind：表示要新建对象的类型

spec.selector：表示需要管理的Pod的label，这里表示包含app: nginx的label的Pod都会被该RC管理

spec.replicas：表示受此RC管理的Pod需要运行的副本数

spec.template：表示用于定义Pod的模板，比如Pod名称、拥有的label以及Pod中运行的应用等

通过改变RC里Pod模板中的镜像版本，可以实现Pod的升级功能

kubectl apply -f nginx-pod.yaml，此时k8s会在所有可用的Node上，创建3个Pod，并且每个Pod都有一个app: nginx的label，同时每个Pod中都运行了一个nginx容器。

如果某个Pod发生问题，Controller Manager能够及时发现，然后根据RC的定义，创建一个新的Pod

扩缩容：kubectl scale rc nginx –replicas=5

example：

  1. 创建名为nginx_replication.yaml

    apiVersion: v1
kind: ReplicationController
metadata:
 name: nginx
spec:
 replicas: 3
 selector:
   app: nginx
 template:
   metadata:
     name: nginx
     labels:
       app: nginx
   spec:
     containers:
     - name: nginx
       image: nginx
       ports:
       - containerPort: 80

  2. 根据nginx_replication.yaml创建pod

    kubectl apply -f nginx_replication.yaml

  3. 查看pod

    kubectl get pods -o wide
  NAME      READY     STATUS
nginx-hksg8   1/1     Running   0          44s   192.168.80.195   w2   
nginx-q7bw5   1/1     Running   0          44s   192.168.190.67   w1  
nginx-zzwzl   1/1     Running   0          44s   192.168.190.68   w1    
kubectl get rc
NAME    DESIRED   CURRENT   READY   AGE
nginx   3         3         3       2m54s

  4. 尝试删除一个pod

    kubectl delete pods nginx-zzwzl
kubectl get pods

  5. 对pod进行扩缩容

    rc = ReplicationController 简写

    kubectl scale rc nginx --replicas=5
kubectl get pods
nginx-8fctt   0/1     ContainerCreating   0          2s
nginx-9pgwk   0/1     ContainerCreating   0          2s
nginx-hksg8   1/1     Running             0          6m50s
nginx-q7bw5   1/1     Running             0          6m50s
nginx-wzqkf   1/1     Running             0          99s

  6. 删除pod

    kubectl delete -f nginx_replication.yaml

ReplicaSet(RS)

官网：https://kubernetes.io/docs/concepts/workloads/controllers/replicaset/

A ReplicaSet’s purpose is to maintain a stable set of replica Pods running at any given time. As such, it is often used to guarantee the availability of a specified number of identical Pods.

在Kubernetes v1.2时，RC就升级成了另外一个概念：Replica Set，官方解释为 “下一代RC”

ReplicaSet和RC没有本质的区别，kubectl中绝大部分作用于RC的命令同样适用于RS

RS与RC唯一的区别是：RS支持基于集合的Label Sel ector（Set-based selector），而RC只支持基于等式的Label Selector（equality-based selector），这使得Replica Set的功能更强

Have a try

apiVersion: extensions/v1beta1
kind: ReplicaSet
metadata:
  name: frontend
spec:
  matchLabels: 
    tier: frontend
  matchExpressions: 
    - {key:tier,operator: In,values: [frontend]}
  template:
  ...

注意：一般情况下，我们很少单独使用Replica Set，它主要是被Deployment这个更高的资源对象所使用，从而形成一整套Pod创建、删除、更新的编排机制。当我们使用Deployment时，无须关心它是如何创建和维护Replica Set的，这一切都是自动发生的。同时，无需担心跟其他机制的不兼容问题（比如ReplicaSet不支持rolling-update但Deployment支持）。

Deployment

官网：https://kubernetes.io/docs/concepts/workloads/controllers/deployment/

A Deployment provides declarative updates for Pods and ReplicaSets.

You describe a desired state in a Deployment, and the Deployment Controller changes the actual state to the desired state at a controlled rate. You can define Deployments to create new ReplicaSets, or to remove existing Deployments and adopt all their resources with new Deployments.

Deployment相对RC最大的一个升级就是我们可以随时知道当前Pod“部署”的进度。

创建一个Deployment对象来生成对应的Replica Set并完成Pod副本的创建过程

检查Deploymnet的状态来看部署动作是否完成（Pod副本的数量是否达到预期的值）

example：

  1. 创建nginx_deployment.yaml文件

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-deployment
  labels: 
    app: nginx
spec:
  replicas: 3
  selector:
    matchLabels:
     app: nginx
  template:
    metadata:
     labels:
      app: nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

  2. 根据nginx_deployment.yaml文件创建pod

    kubectl apply -f nginx_deployment.yaml

  3. 查看pod

    kubectl get pods -o wide

    kubectl get deployment

    kubectl get rs

    kubectl get deployment -o wide

    nginx-deployment-6dd86d77d-f7dxb   1/1     Running   0      22s   192.168.80.198   w2 
nginx-deployment-6dd86d77d-npqxj   1/1     Running   0      22s   192.168.190.71   w1 
nginx-deployment-6dd86d77d-swt25   1/1     Running   0      22s   192.168.190.70   w1

    nginx-deployment[deployment]-6dd86d77d[replicaset]-f7dxb[pod]

  4. 当前nginx的版本

    kubectl get deployment -o wide
NAME    READY   UP-TO-DATE   AVAILABLE   AGE     CONTAINERS   IMAGES      SELECTOR
nginx-deployment   3/3         3     3  3m27s      nginx    nginx:1.7.9   app=nginx

  5. 更新nginx的image版本

    kubectl set image deployment nginx-deployment nginx=nginx:1.9.1

  6. 查询 replicaset 信息

    kubectl get rs -o wide

2 Labels and Selectors

在前面的yaml文件中，看到很多label，顾名思义，就是给一些资源打上标签的

官网：https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/

Labels are key/value pairs that are attached to objects, such as pods. 
apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  labels:
    app: nginx

表示名称为nginx-pod的pod，有一个label，key为app，value为nginx。

我们可以将具有同一个label的pod，交给selector管理

apiVersion: apps/v1
kind: Deployment
metadata: 
  name: nginx-deployment
  labels:
    app: nginx
spec:
  replicas: 3
  selector:             # 匹配具有同一个label属性的pod标签
    matchLabels:
      app: nginx         
  template:             # 定义pod的模板
    metadata:
      labels:
        app: nginx      # 定义当前pod的label属性，app为key，value为nginx
    spec:
      containers:
      - name: nginx
        image: nginx:1.7.9
        ports:
        - containerPort: 80

查看pod的label标签：kubectl get pods –show-labels

这里可以尝试一下selector匹配不上的结果

3 Namespace

kubectl get pods

kubectl get pods -n kube-system

比较一下，上述两行命令的输入是否一样，发现不一样，是因为Pod属于不同的Namespace。

查看一下当前的命名空间：kubectl get namespaces/ns

NAME              STATUS   AGE
default           Active   27m
kube-node-lease   Active   27m
kube-public       Active   27m
kube-system       Active   27m

其实说白了，命名空间就是为了隔离不同的资源，比如：Pod、Service、Deployment等。可以在输入命令的时候指定命名空间-n，如果不指定，则使用默认的命名空间：default。

创建命名空间

myns-namespace.yaml

apiVersion: v1
kind: Namespace
metadata:
  name: myns

kubectl apply -f myns-namespace.yaml

kubectl get namespaces/ns

NAME              STATUS   AGE
default           Active   38m
kube-node-lease   Active   38m
kube-public       Active   38m
kube-system       Active   38m
myns              Active   6s

指定命名空间下的资源

比如创建一个pod，属于myns命名空间下

vi nginx-pod.yaml

kubectl apply -f nginx-pod.yaml 

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  namespace: myns
spec:
  containers:
  - name: nginx-container
    image: nginx
    ports:
    - containerPort: 80

查看myns命名空间下的Pod和资源

kubectl get pods

kubectl get pods -n myns

kubectl get all -n myns

kubectl get pods –all-namespaces #查找所有命名空间下的pod

4 Network

4.1 同一个Pod中的容器通信

接下来就要说到跟Kubernetes网络通信相关的内容咯

我们都知道K8S最小的操作单位是Pod，先思考一下同一个Pod中多个容器要进行通信

由官网的这段话可以看出，同一个pod中的容器是共享网络ip地址和端口号的，通信显然没问题

Each Pod is assigned a unique IP address. Every container in a Pod shares the network namespace, including the IP address and network ports.

那如果是通过容器的名称进行通信呢？就需要将所有pod中的容器加入到同一个容器的网络中，我们把该容器称作为pod中的pause container。

4.2 集群内Pod之间的通信

接下来就聊聊K8S最小的操作单元，Pod之间的通信

我们都之间Pod会有独立的IP地址，这个IP地址是被Pod中所有的Container共享的

那多个Pod之间的通信能通过这个IP地址吗？

我认为需要分两个维度：一是集群中同一台机器中的Pod，二是集群中不同机器中的Pod

准备两个pod，一个nginx，一个busybox

nginx_pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: nginx-pod
  labels:
     app: nginx
spec:
  containers:
   - name: nginx-container
      image: nginx
      ports:
       - containerPort: 80

busybox_pod.yaml

apiVersion: v1
kind: Pod
metadata:
  name: busybox
  labels:
     app: busybox
spec:
  containers:
  - name: busybox
     image: busybox
     command: ['sh', '-c', 'echo The app is running! && sleep 3600']

将两个pod运行起来，并且查看运行情况

kubectl apply -f nginx_pod.yaml

kubectl apply -f busy_pod.yaml

kubectl get pods -o wide

NAME      READY  STATUS    RESTARTS   AGE         IP                NODE  
busybox    1/1   Running      0       49s    192.168.221.70   worker02-kubeadm-k8s   
nginx-pod  1/1   Running      0      7m46s   192.168.14.1     worker01-kubeadm-k8s

发现：nginx-pod的ip为192.168.14.1 busybox-pod的ip为192.168.221.70

同一个集群中同一台机器

(1)来到worker01：ping 192.168.14.1

PING 192.168.14.1 (192.168.14.1) 56(84) bytes of data.
64 bytes from 192.168.14.1: icmp_seq=1 ttl=64 time=0.063 ms
64 bytes from 192.168.14.1: icmp_seq=2 ttl=64 time=0.048 ms

(2)来到worker01：curl 192.168.14.1

<!DOCTYPE html>
<html>
<head>
<title>Welcome to nginx!</title>
<style>
    body {
        width: 35em;
        margin: 0 auto;
        font-family: Tahoma, Verdana, Arial, sans-serif;
    }
</style>

同一个集群中不同机器

(1)来到worker02：ping 192.168.14.1

[root@worker02-kubeadm-k8s ~]# ping 192.168.14.1
PING 192.168.14.1 (192.168.14.1) 56(84) bytes of data.
64 bytes from 192.168.14.1: icmp_seq=1 ttl=63 time=0.680 ms
64 bytes from 192.168.14.1: icmp_seq=2 ttl=63 time=0.306 ms
64 bytes from 192.168.14.1: icmp_seq=3 ttl=63 time=0.688 ms

(2)来到worker02：curl 192.168.14.1，同样可以访问nginx

(3)来到master：

ping/curl 192.168.14.1 访问的是worker01上的nginx-pod

ping 192.168.221.70 访问的是worker02上的busybox-pod

(4)来到worker01：ping 192.168.221.70 访问的是worker02上的busybox-pod

Calico 插件实现集群通信

How to implement the Kubernetes Cluster networking model–Calico

官网：https://kubernetes.io/docs/concepts/cluster-administration/networking/#the-kubernetes-network-model

  • pods on a node can communicate with all pods on all nodes without NAT
  • agents on a node (e.g. system daemons, kubelet) can communicate with all pods on that node
  • pods in the host network of a node can communicate with all pods on all nodes without NAT

4.3 集群内Service-Cluster IP

对于上述的Pod虽然实现了集群内部互相通信，但是Pod是不稳定的，比如通过Deployment管理Pod，随时可能对Pod进行扩缩容，这时候Pod的IP地址是变化的。能够有一个固定的IP，使得集群内能够访问。也就是之前在架构描述的时候所提到的，能够把相同或者具有关联的Pod，打上Label，组成Service。而Service有固定的IP，不管Pod怎么创建和销毁，都可以通过Service的IP进行访问

Service官网：https://kubernetes.io/docs/concepts/services-networking/service/

An abstract way to expose an application running on a set of Pods as a network service.
With Kubernetes you don’t need to modify your application to use an unfamiliar service discovery mechanism. Kubernetes gives Pods their own IP addresses and a single DNS name for a set of Pods, and can load-balance across them.

example：

  1. 创建whoami-deployment.yaml文件，并且apply

      apiVersion: apps/v1
  kind: Deployment
  metadata:
    name: whoami-deployment
    labels:
      app: whoami
  spec:
    replicas: 3
    selector:
      matchLabels:
        app: whoami
    template:
      metadata:
        labels:
          app: whoami
      spec:
        containers:
        - name: whoami
          image: jwilder/whoami
          ports:
          - containerPort: 8000

  2. 查看pod以及service

    whoami-deployment-5dd9ff5fd8-22k9n   192.168.221.80   worker02-kubeadm-k8s
whoami-deployment-5dd9ff5fd8-vbwzp   192.168.14.6     worker01-kubeadm-k8s
whoami-deployment-5dd9ff5fd8-zzf4d   192.168.14.7     worker01-kubeadm-k8s


    kubect get svc:可以发现目前并没有关于whoami的service

      NAME         TYPE        CLUSTER-IP   EXTERNAL-IP   PORT(S)   AGE
  kubernetes   ClusterIP   10.96.0.1            443/TCP   19h

    1. 在集群内正常访问

      curl 192.168.221.80:8000/192.168.14.6:8000/192.168.14.7:8000

  3. 创建whoami的service

    注意：该地址只能在集群内部访问

    kubectl expose deployment whoami-deployment
kubectl get svc    
删除svc   kubectl delete service whoami-deployment
[root@master-kubeadm-k8s ~]# kubectl get svc
NAME                TYPE        CLUSTER-IP       EXTERNAL-IP   PORT(S)    AGE
kubernetes          ClusterIP   10.96.0.1                443/TCP    19h
whoami-deployment   ClusterIP   10.105.147.59           8000/TCP   23s

    可以发现有一个Cluster IP类型的service，名称为whoami-deployment，IP地址为10.101.201.192

  4. 通过Service的Cluster IP访问

      [root@master-kubeadm-k8s ~]# curl 10.105.147.59:8000
  I'm whoami-deployment-678b64444d-b2695
  [root@master-kubeadm-k8s ~]# curl 10.105.147.59:8000
  I'm whoami-deployment-678b64444d-hgdrk
  [root@master-kubeadm-k8s ~]# curl 10.105.147.59:8000
  I'm whoami-deployment-678b64444d-65t88

  5. 具体查看一下whoami-deployment的详情信息，发现有一个Endpoints连接了具体3个Pod

      [root@master-kubeadm-k8s ~]# kubectl describe svc whoami-deployment
  Name:              whoami-deployment
  Namespace:         default
  Labels:            app=whoami
  Annotations:       
  Selector:          app=whoami
  Type:              ClusterIP
  IP:                10.105.147.59
  Port:                8000/TCP
  TargetPort:        8000/TCP
  Endpoints:         192.168.14.8:8000,192.168.221.81:8000,192.168.221.82:8000
  Session Affinity:  None
  Events:

  6. 不妨对whoami扩容成5个

      kubectl scale deployment whoami-deployment --replicas=5

  7. 再次访问：curl 10.105.147.59:8000

  8. 再次查看service具体信息：kubectl describe svc whoami-deployment

  9. 其实对于Service的创建，不仅仅可以使用kubectl expose，也可以定义一个yaml文件

    apiVersion: v1
kind: Service
metadata:
  name: my-service
spec:
  selector:
    app: MyApp
  ports:
    - protocol: TCP
      port: 80
      targetPort: 9376
  type: Cluster

    conclusion：其实Service存在的意义就是为了Pod的不稳定性，而上述探讨的就是关于Service的一种类型Cluster IP，只能供集群内访问

以Pod为中心，已经讨论了关于集群内的通信方式，接下来就是探讨集群中的Pod访问外部服务，以及外部服务访问集群中的Pod

4.4 Pod访问外部服务

比较简单，没太多好说的内容，直接访问即可

4.5 外部服务访问集群中的Pod

Service-NodePort

也是Service的一种类型，可以通过NodePort的方式

说白了，因为外部能够访问到集群的物理机器IP，所以就是在集群中每台物理机器上暴露一个相同的IP，比如32008

  1. 根据whoami-deployment.yaml创建pod

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: whoami-deployment
  labels:
    app: whoami
spec:
  replicas: 3
  selector:
    matchLabels:
      app: whoami
  template:
    metadata:
      labels:
        app: whoami
    spec:
      containers:
      - name: whoami
        image: jwilder/whoami
        ports:
        - containerPort: 8000

  2. 创建NodePort类型的service，名称为whoami-deployment

    kubectl delete svc whoami-deployment
kubectl expose deployment whoami-deployment --type=NodePort
[root@master-kubeadm-k8s ~]# kubectl get svc
NAME                TYPE        CLUSTER-IP     EXTERNAL-IP   PORT(S)          AGE
kubernetes          ClusterIP   10.96.0.1              443/TCP          21h
whoami-deployment   NodePort    10.99.108.82           8000:32041/TCP   7s

  3. 注意上述的端口32041，实际上就是暴露在集群中物理机器上的端口

    lsof -i tcp:32041
netstat -ntlp|grep 32041

  4. 浏览器通过物理机器的IP访问

    http://192.168.0.51:32041
curl 192.168.0.61:32041

conclusion：NodePort虽然能够实现外部访问Pod的需求，但是真的好吗？其实不好，占用了各个物理主机上的端口

Service-LoadBalance

通常需要第三方云提供商支持，有约束性

Ingress

官网：https://kubernetes.io/docs/concepts/services-networking/ingress/

An API object that manages external access to the services in a cluster, typically HTTP.

Ingress can provide load balancing, SSL termination and name-based virtual hosting.

可以发现，Ingress就是帮助我们访问集群内的服务的。不过在看Ingress之前，我们还是先以一个案例出发。

很简单，在K8S集群中部署tomcat

浏览器想要访问这个tomcat，也就是外部要访问该tomcat，用之前的Service-NodePort的方式是可以的，比如暴露一个32008端口，只需要访问192.168.0.61:32008即可。

vi my-tomcat.yaml

kubectl apply -f my-tomcat.yaml

kubectl get pods

kubectl get deployment

kubectl get svc

tomcat-service NodePort 10.105.51.97 <none> 80:31032/TCP 37s

apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deployment
  labels:
    app: tomcat
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tomcat
  template:
    metadata:
      labels:
        app: tomcat
    spec:
      containers:
      - name: tomcat
        image: tomcat
        ports:
        - containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat-service
spec:
  ports:
  - port: 80   
    protocol: TCP
    targetPort: 8080
  selector:
    app: tomcat
  type: NodePort

显然，Service-NodePort的方式生产环境不推荐使用，那接下来就基于上述需求，使用Ingress实现访问tomcat的需求。

官网Ingress: https://kubernetes.io/docs/concepts/services-networking/ingress/
GitHub Ingress Nginx: https://github.com/kubernetes/ingress-nginx
Nginx Ingress Controller: <https://kubernetes.github.io/ingress-nginx/

example：

  1. 下载 mandatory.yaml

    https://github.com/kubernetes/ingress-nginx/edit/master/deploy/static/mandatory.yaml

    apiVersion: v1
kind: Namespace
metadata:
  name: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---

kind: ConfigMap
apiVersion: v1
metadata:
  name: nginx-configuration
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
kind: ConfigMap
apiVersion: v1
metadata:
  name: tcp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
kind: ConfigMap
apiVersion: v1
metadata:
  name: udp-services
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
apiVersion: v1
kind: ServiceAccount
metadata:
  name: nginx-ingress-serviceaccount
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRole
metadata:
  name: nginx-ingress-clusterrole
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
rules:
  - apiGroups:
      - ""
    resources:
      - configmaps
      - endpoints
      - nodes
      - pods
      - secrets
    verbs:
      - list
      - watch
  - apiGroups:
      - ""
    resources:
      - nodes
    verbs:
      - get
  - apiGroups:
      - ""
    resources:
      - services
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - ""
    resources:
      - events
    verbs:
      - create
      - patch
  - apiGroups:
      - "extensions"
      - "networking.k8s.io"
    resources:
      - ingresses
    verbs:
      - get
      - list
      - watch
  - apiGroups:
      - "extensions"
      - "networking.k8s.io"
    resources:
      - ingresses/status
    verbs:
      - update

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: Role
metadata:
  name: nginx-ingress-role
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
rules:
  - apiGroups:
      - ""
    resources:
      - configmaps
      - pods
      - secrets
      - namespaces
    verbs:
      - get
  - apiGroups:
      - ""
    resources:
      - configmaps
    resourceNames:
      # Defaults to "<election-id>-<ingress-class>"
      # Here: "<ingress-controller-leader>-<nginx>"
      # This has to be adapted if you change either parameter
      # when launching the nginx-ingress-controller.
      - "ingress-controller-leader-nginx"
    verbs:
      - get
      - update
  - apiGroups:
      - ""
    resources:
      - configmaps
    verbs:
      - create
  - apiGroups:
      - ""
    resources:
      - endpoints
    verbs:
      - get

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: RoleBinding
metadata:
  name: nginx-ingress-role-nisa-binding
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: Role
  name: nginx-ingress-role
subjects:
  - kind: ServiceAccount
    name: nginx-ingress-serviceaccount
    namespace: ingress-nginx

---
apiVersion: rbac.authorization.k8s.io/v1beta1
kind: ClusterRoleBinding
metadata:
  name: nginx-ingress-clusterrole-nisa-binding
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
roleRef:
  apiGroup: rbac.authorization.k8s.io
  kind: ClusterRole
  name: nginx-ingress-clusterrole
subjects:
  - kind: ServiceAccount
    name: nginx-ingress-serviceaccount
    namespace: ingress-nginx

---

apiVersion: apps/v1
kind: Deployment
metadata:
  name: nginx-ingress-controller
  namespace: ingress-nginx
  labels:
    app.kubernetes.io/name: ingress-nginx
    app.kubernetes.io/part-of: ingress-nginx
spec:
  replicas: 1
  selector:
    matchLabels:
      app.kubernetes.io/name: ingress-nginx
      app.kubernetes.io/part-of: ingress-nginx
  template:
    metadata:
      labels:
        app.kubernetes.io/name: ingress-nginx
        app.kubernetes.io/part-of: ingress-nginx
      annotations:
        prometheus.io/port: "10254"
        prometheus.io/scrape: "true"
    spec:
      # wait up to five minutes for the drain of connections
      terminationGracePeriodSeconds: 300
      serviceAccountName: nginx-ingress-serviceaccount
      nodeSelector:
        kubernetes.io/os: linux
      containers:
        - name: nginx-ingress-controller
          image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.26.1
          args:
            - /nginx-ingress-controller
            - --configmap=$(POD_NAMESPACE)/nginx-configuration
            - --tcp-services-configmap=$(POD_NAMESPACE)/tcp-services
            - --udp-services-configmap=$(POD_NAMESPACE)/udp-services
            - --publish-service=$(POD_NAMESPACE)/ingress-nginx
            - --annotations-prefix=nginx.ingress.kubernetes.io
          securityContext:
            allowPrivilegeEscalation: true
            capabilities:
              drop:
                - ALL
              add:
                - NET_BIND_SERVICE
            # www-data -> 33
            runAsUser: 33
          env:
            - name: POD_NAME
              valueFrom:
                fieldRef:
                  fieldPath: metadata.name
            - name: POD_NAMESPACE
              valueFrom:
                fieldRef:
                  fieldPath: metadata.namespace
          ports:
            - name: http
              containerPort: 80
              protocol: TCP
            - name: https
              containerPort: 443
              protocol: TCP
          livenessProbe:
            failureThreshold: 3
            httpGet:
              path: /healthz
              port: 10254
              scheme: HTTP
            initialDelaySeconds: 10
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 10
          readinessProbe:
            failureThreshold: 3
            httpGet:
              path: /healthz
              port: 10254
              scheme: HTTP
            periodSeconds: 10
            successThreshold: 1
            timeoutSeconds: 10
          lifecycle:
            preStop:
              exec:
                command:
                  - /wait-shutdown

---

  2. 以Deployment方式创建Pod，该Pod为Ingress Nginx Controller，要想让外界访问，可以通过Service的NodePort或者HostPort方式，这里选择HostPort，比如指定worker01运行

    # 确保nginx-controller运行到w1节点上
kubectl label node w1 name=ingress   
# 使用HostPort方式运行，需要增加配置
hostNetwork: true
# 搜索nodeSelector，并且要确保w1节点上的80和443端口没有被占用，镜像拉取需要较长的时间，这块注意一下哦
# mandatory.yaml在网盘中的“课堂源码”目录
kubectl apply -f mandatory.yaml  
kubectl get all -n ingress-nginx

    新增如图所示配置，根据 name=ingress 选择运行的节点，hostNetwork=true 以 HostPort 的方式暴露端口

    执行 yaml 文件，并查看 namespace 下 pod

  3. 查看w1的80和443端口

    lsof -i tcp:80
lsof -i tcp:443

  4. 创建tomcat的pod和service

    记得将之前的tomcat删除：kubectl delete -f my-tomcat.yaml

    vi tomcat.yaml
kubectl apply -f tomcat.yaml
kubectl get svc 
kubectl get pods

    tomcat.yaml 内容：

    apiVersion: apps/v1
kind: Deployment
metadata:
  name: tomcat-deployment
  labels:
    app: tomcat
spec:
  replicas: 1
  selector:
    matchLabels:
      app: tomcat
  template:
    metadata:
      labels:
        app: tomcat
    spec:
      containers:
      - name: tomcat
        image: tomcat
        ports:
        - containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
  name: tomcat-service
spec:
  ports:
  - port: 80   
    protocol: TCP
    targetPort: 8080
  selector:
    app: tomcat
  type: NodePort

  5. 创建Ingress以及定义转发规则

    kubectl apply -f my-ingress.yaml
kubectl get ingress
kubectl describe ingress nginx-ingress

    my-ingress.yaml 内容：

    #ingress
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
 name: nginx-ingress
spec:
 rules:
 - host: tomcat.jack.com
   http:
     paths:
     - path: /
       backend:
         serviceName: tomcat-service
         servicePort: 80

    规则说明：访问 tomcat.jack.com 的根目录时，会被转发到下面的 tomcat-service 服务，tomcat服务的地址是 192.168.19.77:8080

  6. 修改win的hosts文件，添加dns解析

    192.168.8.61 tomcat.jack.com
# 这里配置 w1 节点的ip和域名对应（实际配置如下）
172.16.11.129   tomcat.jack.com

  7. 打开浏览器，访问tomcat.jack.com

总结：如果以后想要使用Ingress网络，其实只要定义ingress，service和pod即可，前提是要保证 nginx ingress controller 已经配置好了。

文章作者: Soulballad
文章链接: https://soulballad.github.io/posts/46512102
版权声明: 本博客所有文章除特別声明外，均采用 CC BY 4.0 许可协议。转载请注明来源 Soulballad !
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