k8s资源对象-ingress通俗理解及配置使用
目录
理论
什么是ingress
简单理解，ingress就是将pod所提供的服务暴露出来，能够让k8s集群外部访问到对应的服务。
为什么要使用ingress？
除了可以使用ingress。我目前使用过的还有nodeport，nodeport直接映射集群中每台主机的端口，可以通过访问集群中任意一台主机的地址+端口来访问对应的服务。
用nodeport不好么？多出了这么个东西是为了解决什么问题？
我仔细琢磨了下，k8s的设计思想就是将整个k8s集群作为逻辑上的一台主机，每个pod相当于一个或一组相关进程。
对，我们一定可以这么理解：nodeport就相当于在Linux主机上的服务进程端口，用户访问时直接通过IP+端口可以访问；那么ingress（或许叫做ingress-controller更合适）就是一个nginx之类的反向代理，将需要反向代理的服务全部都塞到配置文件里，我们只需要访问ingress暴露出来的端口就可以（通过不同域名来区分，或者是根据url来区分）。
但是和Linux主机所不同的是：就算我们不是很理解，但是要知道一个事实，Linux主机上的服务进程端口就算用nginx做统一管理，统一反向代理；但是它自身不会减少主机暴露的端口，只是它会对用户层面隐藏掉。但是ingress就不一样了，它是真正减少暴露宿主机的端口的；我们创建pod提供服务，肯定要暴露出来端口啊，它是怎么做到的？这是当然，只不过笔者能力有限，我尝试着这样说明一下：创建pod提供必需要暴露端口，这是进程之间通信也好，用户访问也好，都需要的。只不过在k8s中，有了service这个概念，service的端口开放，但是不占用宿主机的，如果我们不做别的操作，它只能在集群内部进行访问。
ingress就是如此，接受到请求，根据配置转发，反向代理到后面的service
如上理论个人理解，不官方
撸部署撸配置
之前称呼的ingress有些不严谨，ingress相当于使用nginx的server段，而ingress-controller可以类比nginx自身，而ingress-controller有很多中，Nginx，HAProxy，Envoy，Traefik，只是nginx比较广泛，好理解。
部署一个ingress-nginx
官方yaml文件地址：https://raw.githubusercontent.com/kubernetes/ingress-nginx/nginx-0.30.0/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:0.30.0 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: Container
配置很多，原理很简单，这个Pod本身，就是一个监听Ingress对象以及它所代理的服务变化的控制器。当一个新的Ingress对象由用户创建后，nginx-ingress-controller就会根据Ingress对象里定义的内容，生成副本对应的Nginx配置文件（/etc/nginx/nginx.conf），并使用这个配置文件启动一个Nginx服务。
接下来的配置就相当于，我们创建了一个nginx，接下来要为它指定访问的入口，也就是定义service
apiVersion: v1 kind: Service metadata: name: ingress-nginx namespace: ingress-nginx labels: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx spec: type: NodePort ports: - name: http port: 80 targetPort: 80 protocol: TCP nodePort: 80 - name: https port: 443 targetPort: 443 protocol: TCP nodePort: 443 selector: app.kubernetes.io/name: ingress-nginx app.kubernetes.io/part-of: ingress-nginx如配置所写：我将宿主机的80映射到容器的默认80，443对应443，很方便
好，那再接下来，我们有了nginx反向代理，我们要配置它代理谁了；我这里又个后端的私有服务端口8080
不过在这之前，我想配置https了，我下面说说，https和http分别的配置
https：
? 首先将已有的crt和key文件创建成secret对象，以便使用
? ingress-secret.yml
apiVersion: v1 data: tls.crt: UVVITUFHR0dHaDBkSEE2Ckx5OXZZM053TG1kdlpHRmtaS #你的crt经过base64编码之后放到这里，我这只是示范，注意空格换行都不要。 #cat key | base64 | tr ‘\n‘ ‘ ‘ | sed ‘s/ //g‘ tls.key: xVWE3Q2FDbjNobis4QzkxM2FyOUNSNXZ #同上，值得注意的是tls.crt和tls.key这个字段，我之前以为只是一个名称，可以改写。但是这两个字段是关键词，死的，不能动。 kind: Secret metadata: name: ingress-secret namespace: default #注意名称空间，要和待会我创建的ingress在一个名称空间内，否则不生效 type: kubernetes.io/tls
? ingress.yml，创建ingress，和提供服务的pod的service端口必须对应。
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: keycloak namespace: default spec: tls: - hosts: - key.123456.com secretName: ingress-secret #之前的secretname字段必须相同 rules: - host: key.123456.com http: paths: - backend: serviceName: keycloak servicePort: 8080自行使用apply进行创建，并查看验证,严格注意名称空间
http:文件示例
apiVersion: extensions/v1beta1 kind: Ingress metadata: name: *** namespace: kube-system spec: rules: - host: dashboard.mritd.me http: paths: - backend: serviceName: kubernetes-dashboard servicePort: 80 - host: kibana.mritd.me http: paths: - backend: serviceName: kibana-logging servicePort: 5601
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