目前k8s+docker算是运维必修了，docker能让我们的环境一键迁移，k8s能自动编排,还能保证服务高可用，两者结合自然是无敌，那我们要不要使用k8s呢？这要根据自身情况，任何技术的使用，都需要根据具体情况来定，就像你要杀鸡，却非要选牛刀，牛刀是很锋利，但还不够你折腾的
本文重点介绍k8s集群外如何访问集群内的服务，主要方式有：hostPort或hostNetwork、NodePort、Ingress
hostPort和hostNetwork 放在首位是因为大家很容易忽略它们，它们也可让集群外访问集群内应用，用法：
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: nginx
name: nginx-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
nodeSelector: # node节点选择器
role: master # node节点标签(Label)
hostNetwork: true # 使用node节点网络
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: nginx
ports:
- containerPort: 8080重点在和containers平级的hostNetwork: true,表示pod使用宿主机网络，配合nodeSelector，把pod实例化在固定节点，如上，我给mater节点加上标签role: master,通过nodeSelector,nginx就会实例化在master节点，这样就可以通过master节点的ip和8080端口访问这个nginx了
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: nginx
name: nginx-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
nodeSelector: # node节点选择器
role: master # node节点标签(Label)
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: nginx
ports:
- containerPort: 8080
hostPort: 80 #重点和hostNetwork相比多了映射能力，可以把容器端口映射为node节点不同端口，hostPort,当然也需要nodeSelector来固定节点，不然每次创建，节点不同，ip也会改变
访问方式：nodeSelector所选节点ip:hostPort, 如上：role=Master标签节点Ip:80
NodePort是最常见的提供集群外访问的方式之一，该方式使用Service提供集群外访问
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: nginx
name: nginx-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: nginx
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: nginx-pod-service
labels:
app: nginx #自身标签
spec:
type: NodePort # 类型ExternalName, ClusterIP, NodePort, and LoadBalancer
ports:
- port: 8080 # service在k8s集群内服务端口
targetPort: 8080 # 关联pod对外开放端口
nodePort: 30088 # 集群外访问端口，端口范围【30000-32767】
selector:
app: nginx # pod标签访问方式：集群内任意节点ip加nodePort所配端口号，如上：集群内任一节点ip:30088，即可访问nginx
Ingress基本生产必备，可以简单理解为部署了一个nginx服务，该服务使用hostNetwork或hostPort方式提供集群外访问，再根据配置的路由规则，路由的集群内部各个service
Ingress有各种实现版本，这里安装的为ingress-nginx,其yaml文件如下：ingress.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: #注意修改自己nodeSelector
role: master
hostNetwork: true
containers:
- name: nginx-ingress-controller
image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.30.0
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 -> 101
runAsUser: 101
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
---
apiVersion: v1
kind: LimitRange
metadata:
name: ingress-nginx
namespace: ingress-nginx
labels:
app.kubernetes.io/name: ingress-nginx
app.kubernetes.io/part-of: ingress-nginx
spec:
limits:
- min:
memory: 90Mi
cpu: 100m
type: Containerkubectl apply -f ingress.yaml该yaml会创建ingress-nginx命名空间，待对应pod进入running状态，ingress服务就安装完成了
apiVersion: apps/v1
kind: Deployment
metadata:
labels:
app: nginx
name: nginx-deployment
spec:
replicas: 1
selector:
matchLabels:
app: nginx
template:
metadata:
labels:
app: nginx
spec:
containers:
- image: nginx
imagePullPolicy: IfNotPresent
name: nginx
ports:
- containerPort: 8080
---
apiVersion: v1
kind: Service
metadata:
name: nginx-pod-service
labels:
app: nginx #自身标签
spec:
type: NodePort # 类型ExternalName, ClusterIP, NodePort, and LoadBalancer
ports:
- port: 8080 # service在k8s集群内服务端口
targetPort: 8080 # 关联pod对外开放端口
selector:
app: nginx # pod标签
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-ingress
labels:
app.kubernetes.io/version: v1
annotations:
nginx.ingress.kubernetes.io/rewrite-target: /
spec:
rules:
- host: nginx.test.com
http:
paths:
- path: /
backend:
serviceName: nginx-pod-service # 上面nginx Service配置的name
servicePort: 8080 # Service配置的port集群外配置好host
ingress服务部署节点的ip nginx.test.com 通过域名进行访问，且仅能通过域名
hostPort和hostNetwork直接使用节点网络，部署时节点需固定，访问ip也固定(也可以用host)，端口为正常端口
nodeport方式部署时不要求固定节点，可通过集群内任一ip进行访问，就是端口为30000以上，很多时候由于公司安全策略导致不能访问
ingress需要额外安装ingress模块，配置路由规则，且仅能通过所配置域名访问，配置好域名后，可以直接对外提供服务，和传统的nginx作用类似
可根据各自情况灵活使用