k8s Ingress 服务部署方式
通常情况下，service和pod仅可在集群内部网络中通过IP地址访问。所有到达边界路由器的流量或被丢弃或被转发到其他地方
官网对 Ingress 的定义为管理对外服务到集群内服务之间规则的集合，通俗点讲就是它定义规则来允许进入集群的请求被转发到集群中对应服务上，从来实现服务暴漏。Ingress 能把集群内 Service 配置成外网能够访问的 URL，流量负载均衡，终止SSL，提供基于域名访问的虚拟主机等等。
Ingress
Ingress 使用开源的反向代理负载均衡器来实现对外暴漏服务，比如 Nginx、Apache、Haproxy等。Nginx Ingress 一般有三个组件组成：
Nginx 反向代理负载均衡器
Ingress Controller
Ingress Controller 可以理解为控制器，它通过不断的跟 Kubernetes API 交互，实时获取后端 Service、Pod 等的变化，比如新增、删除等，然后结合 Ingress 定义的规则生成配置，然后动态更新上边的 Nginx 负载均衡器，并刷新使配置生效，来达到服务自动发现的作用。
Ingress
Ingress 则是定义规则，通过它定义某个域名的请求过来之后转发到集群中指定的 Service。它可以通过 Yaml 文件定义，可以给一个或多个 Service 定义一个或多个 Ingress 规则。
以上三者有机的协调配合起来，就可以完成 Kubernetes 集群服务的暴漏
Kubernetes 使用 Nginx Ingress 暴漏tomcat服务，前提我们需要有一个正常运行的集群服务，根据之前创建的的kubernetes集群，进行测试
使用到的镜像
gcr.io/google_containers/defaultbackend:1.4
quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.18.0
ingress-nginx组件有几个部分组成：
configmap.yaml:提供configmap可以在线更行nginx的配置
default-backend.yaml:提供一个缺省的后台错误页面 404
namespace.yaml:创建一个独立的命名空间 ingress-nginx
rbac.yaml:创建对应的role rolebinding 用于rbac
tcp-services-configmap.yaml:修改L4负载均衡配置的configmap
udp-services-configmap.yaml:修改L4负载均衡配置的configmap
nginx-ingress-controller.yaml:有应用rbac的nginx-ingress-controller组件
YAML配置文件
namespace.yaml
apiVersion: v1
kind: Namespace
metadata:
name: ingress-nginx
default-backend.yaml
apiVersion: extensions/v1beta1
kind: Deployment
metadata:
name: default-http-backend
labels:
app.kubernetes.io/name: default-http-backend
app.kubernetes.io/part-of: ingress-nginx
namespace: ingress-nginx
spec:
replicas: 1
selector:
matchLabels:
app.kubernetes.io/name: default-http-backend
app.kubernetes.io/part-of: ingress-nginx
template:
metadata:
labels:
app.kubernetes.io/name: default-http-backend
app.kubernetes.io/part-of: ingress-nginx
spec:
terminationGracePeriodSeconds: 60
containers:
- name: default-http-backend
image: googlecontainer/defaultbackend-amd64:1.4
#image:
livenessProbe:
httpGet:
path: /healthz
port: 8080
scheme: HTTP
initialDelaySeconds: 30
timeoutSeconds: 5
ports:
- containerPort: 8080
resources:
limits:
cpu: 10m
memory: 20Mi
requests:
cpu: 10m
memory: 20Mi
---
apiVersion: v1
kind: Service
metadata:
name: default-http-backend
namespace: ingress-nginx
labels:
app.kubernetes.io/name: default-http-backend
app.kubernetes.io/part-of: ingress-nginx
spec:
ports:
- port: 80
targetPort: 8080
selector:
app.kubernetes.io/name: default-http-backend
app.kubernetes.io/part-of: ingress-nginx
---
configmap.yaml
kind: ConfigMap
apiVersion: v1
metadata:
name: nginx-configuration
namespace: ingress-nginx
labels:
app: ingress-nginx
tcp-services-configmap.yaml
kind: ConfigMap
apiVersion: v1
metadata:
name: tcp-services
namespace: ingress-nginx
udp-services-configmap.yaml
kind: ConfigMap
apiVersion: v1
metadata:
name: udp-services
namespace: ingress-nginx
rbac.yaml
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:
- "extensions"
resources:
- ingresses
verbs:
- get
- list
- watch
- apiGroups:
- ""
resources:
- events
verbs:
- create
- patch
- apiGroups:
- "extensions"
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
---
nginx-ingress-controller.yaml
apiVersion: extensions/v1beta1
kind: DaemonSet
metadata:
name: nginx-ingress-controller
namespace: ingress-nginx
spec:
selector:
matchLabels:
app: ingress-nginx
template:
metadata:
labels:
app: ingress-nginx
annotations:
prometheus.io/port: '10254'
prometheus.io/scrape: 'true'
spec:
serviceAccountName: nginx-ingress-serviceaccount
hostNetwork: true
containers:
- name: nginx-ingress-controller
image: quay.io/kubernetes-ingress-controller/nginx-ingress-controller:0.18.0
args:
- /nginx-ingress-controller
- --default-backend-service=$(POD_NAMESPACE)/default-http-backend
- --configmap=$(POD_NAMESPACE)/nginx-configuration
- --tcp-services-configmap=$(POD_NAMESPACE)/tcp-services
- --udp-services-configmap=$(POD_NAMESPACE)/udp-services
- --annotations-prefix=nginx.ingress.kubernetes.io
env:
- name: POD_NAME
valueFrom:
fieldRef:
fieldPath: metadata.name
- name: POD_NAMESPACE
valueFrom:
fieldRef:
fieldPath: metadata.namespace
ports:
- name: http
containerPort: 80
- name: https
containerPort: 443
livenessProbe:
failureThreshold: 3
httpGet:
path: /healthz
port: 10254
scheme: HTTP
initialDelaySeconds: 10
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
readinessProbe:
failureThreshold: 3
httpGet:
path: /healthz
port: 10254
scheme: HTTP
periodSeconds: 10
successThreshold: 1
timeoutSeconds: 1
#nodeSelector:
#custom/ingress-controller-ready: "true"
说明：
kind: DaemonSet：官方文档给的是deployment，replicate 为 1，这样将会在某一台节点上启动对应的nginx-ingress-controller pod。外部流量访问至该节点，由该节点负载分担至内部的service。测试环境考虑防止单点故障，改为DaemonSet，配合亲和性部署在制定节点上启动nginx-ingress-controller pod，确保有多个节点启动nginx-ingress-controller pod，后续将这些节点加入到外部硬件负载均衡组实现高可用性。
hostNetwork: true：添加该字段，暴露nginx-ingress-controller pod的服务端口（80）
nodeSelector: 加入亲和性部署，有custom/ingress-controller-ready label的才会部署该DaemonSet（未使用）
加载yaml文件
kubectl create -f .
查看pod创建情况
#kubectl get pod,svc,deployment -n ingress-nginx -o wide
在上面已经部署了 ingress-nginx，下面我们部署一个tomcat作为对外暴露的服务
使用ingress部署一个对外暴露的服务包含一个pod和一个service
创建tomcat service yaml
vi tomcat-deploy.yaml
复制下面的内容：
apiVersion: v1
kind: Service
metadata:
name: tomcat
namespace: default
spec:
selector:
app: tomcat
release: canary
ports:
- name: http
targetPort: 8080
port: 8080
- name: ajp
targetPort: 8009
port: 8009
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: tomcat-deploy
namespace: default
spec:
replicas: 1
selector:
matchLabels:
app: tomcat
release: canary
template:
metadata:
labels:
app: tomcat
release: canary
spec:
containers:
- name: tomcat
image: tomcat
ports:
- name: http
containerPort: 8080
创建tomcat pod yaml文件
vi ingress-tomcat.yaml
复制下面内容：
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: ingress-tomcat
namespace: default
annotations:
kubernetes.io/ingress.class: "nginx"
spec:
rules:
- host: k8s.master ##这个地方使用主机名或者域名，不能使用IP地址
http:
paths:
- path:
backend:
serviceName: tomcat
servicePort: 8080
然后执行：
kubectl apply -f tomcat-deploy.yaml
kubectl apply -f ingress-tomcat.yaml
服务启动以后就可以通过上面配置的主机名或者域名进行访问tomcat 了
