k3sでingressを使う
はじめに
Kubernetesの機能であるIngressを使います．IngressはTCP/IPのLayer 7(つまりHTTP)のレベルでアクセスを制御するKubenetesの機能です．具体的には，URLルーティングを行います．これは http://example.com/hello と http://example.com/world で別のサーバ（コンテナ）を参照させることです．IngressにはKubenetesクラスタの内部に構築するものと，外部に構築するものがあります．今回は内部に構築するものを使います．
Nginx Ingressを動かす
Nginx Ingressを動かす． https://kubernetes.github.io/ingress-nginx/deploy/
インストール
$ sudo k3s kubectl apply -f https://raw.githubusercontent.com/kubernetes/ingress-nginx/controller-0.32.0/deploy/static/provider/baremetal/deploy.yaml
確認
$ alias k='sudo k3s kubectl' # これ便利です
$ k get pods -n ingress-nginx -l app.kubernetes.io/name=ingress-nginx --watch
NAME READY STATUS RESTARTS AGE
ingress-nginx-admission-patch-7hjpr 0/1 Completed 0 82s
ingress-nginx-admission-create-6gfst 0/1 Completed 0 82s
ingress-nginx-controller-f8d756996-bb6gz 1/1 Running 0 92s
Ingressを使ったデプロイ
以下のファイルをデプロイする．
$ k apply -f ingress-app.yaml
$ k apply -f ingress-controller.yaml
ingress-app.yaml
apiVersion: apps/v1
kind: Deployment
metadata:
name: get-my-host
labels:
app: hostname
spec:
replicas: 3
selector:
matchLabels:
app: hostname
template:
metadata:
labels:
app: hostname
spec:
containers:
- name: host-app
image: adongy/hostname-docker
ports:
- containerPort: 3000
---
apiVersion: v1
kind: Service
metadata:
name: get-my-host
spec:
type: NodePort
selector:
app: hostname
ports:
- name: "http-port"
protocol: "TCP"
port: 4000
targetPort: 3000
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: get-my-info
labels:
app: nginxdemo
spec:
replicas: 3
selector:
matchLabels:
app: nginxdemo
template:
metadata:
labels:
app: nginxdemo
spec:
containers:
- name: info-app
image: nginxdemos/hello
ports:
- containerPort: 80
---
apiVersion: v1
kind: Service
metadata:
name: get-my-info
spec:
type: NodePort
selector:
app: nginxdemo
ports:
- name: "http-port"
protocol: "TCP"
port: 4000
targetPort: 80
ingress-controller.yaml
---
apiVersion: extensions/v1beta1
kind: Ingress
metadata:
name: nginx-ingress
annotations:
ingress.kubernetes.io/ssl-redirect: "false"
ingress.kubernetes.io/rewrite-target: "/"
spec:
rules:
- http:
paths:
- path: /hello
backend:
serviceName: get-my-info
servicePort: 4000
- path: /world
backend:
serviceName: get-my-host
servicePort: 4000
うまく動いていた時
$ k get all
NAME READY STATUS RESTARTS AGE
pod/my-ingress-default 1/1 Running 0 11h
pod/get-my-info-6666748778-5gxnv 1/1 Running 0 5m1s
pod/get-my-host-7449f7cf55-6hjzg 1/1 Running 0 5m1s
pod/get-my-info-6666748778-nxlgs 1/1 Running 0 5m1s
pod/get-my-info-6666748778-vzmxx 1/1 Running 0 5m1s
pod/get-my-host-7449f7cf55-d8bm7 1/1 Running 0 5m1s
pod/get-my-host-7449f7cf55-ncrvz 1/1 Running 0 5m1s
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
service/kubernetes ClusterIP 10.43.0.1 <none> 443/TCP 13h
service/get-my-host NodePort 10.43.140.123 <none> 4000:32265/TCP 5m1s
service/get-my-info NodePort 10.43.73.32 <none> 4000:31270/TCP 5m1s
NAME READY UP-TO-DATE AVAILABLE AGE
deployment.apps/get-my-info 3/3 3 3 5m1s
deployment.apps/get-my-host 3/3 3 3 5m1s
NAME DESIRED CURRENT READY AGE
replicaset.apps/get-my-info-6666748778 3 3 3 5m1s
replicaset.apps/get-my-host-7449f7cf55 3 3 3 5m1s
$ k get ingress
NAME HOSTS ADDRESS PORTS AGE
nginx-ingress * 192.168.0.17 80 11h
ブラウザからアクセスしてみる．
ユーザのリクエストがコンテナに到達するまでのながれ
hnote over User: ブラウザからアクセス
User -> "ingress-endpoint \n[LoadBalancer Service]"
hnote over "ingress-endpoint \n[LoadBalancer Service]": L4(IP/ポート)\nロードバランサ\nDeploymentの選択
"ingress-endpoint \n[LoadBalancer Service]" -> "nginx-ingress-controller \n[Deployment]"
hnote over "nginx-ingress-controller \n[Deployment]": L7(HTTP)\nロードバランサ\nServiceの選択
"nginx-ingress-controller \n[Deployment]" -> "get-my-info \n[NodePort Service]"
hnote over "get-my-info \n[NodePort Service]": L4(IP/ポート)\nロードバランサ\nDeploymentの選択
"get-my-info \n[NodePort Service]" -> "get-my-info \n[Deployment]"
' "get-my-info \n[Deployment]" -> "get-my-info-xxx \n[ReplicaSet]"
' "get-my-info-xxx \n[ReplicaSet]" -> "get-my-info-yyy \n[Pod]"
Deploymentの内側
frame "deployment.apps/get-my-host" {
frame replicaset.apps/get-my-host-7449f7cf55 {
component "pod/get-my-host-7449f7cf55-6hjzg"
component "pod/get-my-host-7449f7cf55-d8bm7"
component "pod/get-my-host-7449f7cf55-ncrvz"
}
}
frame "deployment.apps/get-my-info" {
frame replicaset.apps/get-my-info-6666748778 {
component "pod/get-my-info-6666748778-5gxnv"
component "pod/get-my-info-6666748778-nxlgs"
component "pod/get-my-info-6666748778-vzmxx"
}
}
'deployment.apps/~get-my-host --> ~deployment.apps/get-my-info