基本使用
基本功能-serving
本小节会按照“从零开始写一个 go 应用”的流程，来梳理功能
编写 go 代码
$ cat hello.go
package main
import (
"fmt"
"log"
"net/http"
)
func handler(w http.ResponseWriter, r *http.Request) {
fmt.Fprintf(w, "hello, world!\n")
}
func main() {
http.HandleFunc("/", handler)
port := "8080"
log.Fatal(http.ListenAndServe(fmt.Sprintf(":%s", port), nil))
}在 serving 体系下编写 go 应用，跟常规 go web 开发并无区别
构造镜像
$ cat Dockerfile
FROM golang:1.13 as builder
WORKDIR /app
COPY . ./
RUN CGO_ENABLED=0 GOOS=linux go build -v -o server
FROM alpine:3
RUN apk add --no-cache ca-certificates
COPY --from=builder /app/server /server
CMD ["/server"]
$ docker build . -t dev.local/hello-go:serving常规编译，没什么要补充的
部署应用
$ cat service.yaml
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: hello-go
spec:
template:
spec:
containers:
- image: dev.local/hello-go:serving
$ kubectl apply -f service.yaml创建 ksvc 涉及的完整流程是：
创建了 ksvc
kubectl get ksvc NAME URL LATESTCREATED LATESTREADY READY REASON hello-go http://hello-go.default.example.com hello-go-6wdlw hello-go-6wdlw Truecontroller 依据 ksvc 创建了对应的 rt、cfg
$ kubectl get rt NAME URL READY REASON hello-go http://hello-go.default.example.com True $ kubectl get cfg NAME LATESTCREATED LATESTREADY READY REASON hello-go hello-go-6wdlw hello-go-6wdlw Truecontroller 依据 cfg 创建了对应的 rev
$ kubectl get rev NAME CONFIG NAME K8S SERVICE NAME GENERATION READY REASON hello-go-6wdlw hello-go hello-go-6wdlw 1 Truecontroller 依据 rt 创建了 king
$ kubectl get king NAME READY REASON hello-go Truenetworking-istio 依据 king 创建了 VirtualService(vs)，后者是 istio CRD，接下来就是 istio 的逻辑了，这里就不再展开
$ kubectl get vs NAME GATEWAYS HOSTS AGE hello-go-ingress [knative-serving/cluster-local-gateway knative-serving/knative-ingress-gateway] [hello-go.default hello-go.default.example.com hello-go.default.svc hello-go.default.svc.cluster.local] 2d20h hello-go-mesh [mesh] [hello-go.default hello-go.default.svc hello-go.default.svc.cluster.local] 2d20hcontroller 依据 rev 创建了 kpa
$ kubectl get kpa NAME DESIREDSCALE ACTUALSCALE READY REASON hello-go-6wdlw 0 0 False NoTrafficautoscaler 依据 kpa 创建了 sks
$ kubectl get sks NAME MODE ACTIVATORS SERVICENAME PRIVATESERVICENAME READY REASON hello-go-6wdlw Proxy 2 hello-go-6wdlw hello-go-6wdlw-private Unknown NoHealthyBackendscontroller 依据 rev 创建了 deploy
svc 的创建要稍微麻烦一些，实际上创建了3个 service
$ kubectl get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE hello-go ExternalName <none> cluster-local-gateway.istio-system.svc.cluster.local <none> 2d21h hello-go-6wdlw ClusterIP 10.96.213.237 <none> 80/TCP 2d21h hello-go-6wdlw-private ClusterIP 10.108.110.187 <none> 80/TCP,9090/TCP,9091/TCP,8022/TCP 2d21h我们的用例只用到了其中一个，其它的如 hello-go，是用于外部域名到内部域名映射用的，我们用例中不涉及
注意一些细节，比如：svc 是指向 activator 的；部分 svc 没有 selector（Knative 自己来同步）
$ kubectl get ep hello-go-6wdlw NAME ENDPOINTS AGE hello-go-6wdlw 10.244.0.71:8012 2d21h $ kubectl -n knative-serving get pod activator-68cbc9b5c7-6fsc2 -o wide NAME READY STATUS RESTARTS AGE IP NODE NOMINATED NODE READINESS GATES activator-68cbc9b5c7-6fsc2 1/1 Running 0 5d17h 10.244.0.71 n227-020-128 <none> <none>
访问应用
# 查看应用 URL 后访问
$ kubectl get ksvc
NAME URL LATESTCREATED LATESTREADY READY REASON
hello-go http://hello-go.default.example.com hello-go-6wdlw hello-go-6wdlw True
$ curl -H "Host: hello-go.default.example.com" http://$INTERNAL_INGRESS_HOST
hello, world!访问应用涉及的完整流程是：
访问请求发送到 istio gateway
istio 会完成域名到 k8s svc 的解析，访问请求转发到 activator
activator 触发 deploy 扩容
访问新建 pod，返回响应
如果是较为频繁的访问，则还会触发其它的逻辑
$ hey -n 1000000 -c 300 -m GET -host hello-go.default.example.com http://$INTERNAL_INGRESS_HOSTautoscaler 更新 sks
controller 更新 ep，由 activator 改为应用 pod
$ kubectl get ep hello-go-6wdlw NAME ENDPOINTS AGE hello-go-6wdlw 10.244.0.102:8012,10.244.0.103:8012,10.244.0.104:8012 + 1 more... 2d22h
小结
因为 serving 涉及的 CRD 比较多，这里再把它们统一放这里梳理一下，一图胜千言：
基本功能-eventing
本小节会按照“从零开始写一个 go 应用”的流程，来梳理功能
编写 go 代码
$ cat hello.go
package main
import (
"context"
"log"
cloudevents "github.com/cloudevents/sdk-go/v2"
)
type HelloWorld struct {
Msg string `json:"msg,omitempty"`
}
func receive(ctx context.Context, event cloudevents.Event) (*cloudevents.Event, cloudevents.Result) {
data := &HelloWorld{}
if err := event.DataAs(data); err != nil {
log.Printf("Error while extracting cloudevent Data: %s\n", err.Error())
return nil, cloudevents.NewHTTPResult(400, "failed to convert data: %s", err)
}
log.Printf("Hello World Message from received event %q", data.Msg)
return nil, nil
}
func main() {
c, err := cloudevents.NewDefaultClient()
if err != nil {
log.Fatalf("failed to create client, %v", err)
}
log.Fatal(c.StartReceiver(context.Background(), receive))
}
$ cat go.mod
module hello-eventing
go 1.13
require github.com/cloudevents/sdk-go/v2 v2.0.0-RC2在 eventing 体系下编写 go 应用，需要借助 cloudevents sdk
构造镜像
$ cat Dockerfile
FROM golang:1.13 as builder
WORKDIR /app
ENV GOPROXY https://goproxy.cn,direct
COPY go.* ./
RUN go mod download
COPY . ./
RUN CGO_ENABLED=0 GOOS=linux go build -v -o server
FROM alpine:3
RUN apk add --no-cache ca-certificates
COPY --from=builder /app/server /server
CMD ["/server"]
$ docker build . -t dev.local/hello-go:eventing常规编译，没什么要补充的
部署应用
$ cat app.yaml
apiVersion: v1
kind: Namespace
metadata:
name: knative-samples
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: hello-go
namespace: knative-samples
spec:
replicas: 1
selector:
matchLabels: &labels
app: hello-go
template:
metadata:
labels: *labels
spec:
containers:
- name: hello-go
image: dev.local/hello-go:eventing
---
apiVersion: v1
kind: Service
metadata:
name: hello-go
namespace: knative-samples
spec:
selector:
app: hello-go
ports:
- protocol: TCP
port: 80
targetPort: 8080这里部署的都是 k8s 原生对象，没什么要补充的
创建 broker
$ cat broker.yaml
apiVersion: eventing.knative.dev/v1
kind: Broker
metadata:
name: default
namespace: knative-samples
spec: {}
$ kubectl apply -f broker.yaml创建 broker 涉及的完整流程是：
创建了 broker
$ kubectl -n knative-samples get broker NAME URL AGE READY REASON default http://broker-ingress.knative-eventing.svc.cluster.local/knative-samples/default 4m31s Truemt-broker-controller 将 channel 地址填充到 broker status
$ kubectl -n knative-samples get broker default -o yaml | grep channelAddress knative.dev/channelAddress: http://default-kne-trigger-kn-channel.knative-samples.svc.cluster.local而这个地址实际上也就是指向了 imc-dispatcher
$ kubectl -n knative-samples get svc NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE default-kne-trigger-kn-channel ExternalName <none> imc-dispatcher.knative-eventing.svc.cluster.local <none> 16heventing-controller 依据 broker 创建了对应的 imc
$ kubectl -n knative-samples get imc NAME URL AGE READY REASON default-kne-trigger http://default-kne-trigger-kn-channel.knative-samples.svc.cluster.local 4m35s Trueimc 中将 broker-filter 作为 subscriber
$ kubectl -n knative-samples get imc default-kne-trigger -o yaml | grep subscriberUri subscriberUri: http://broker-filter.knative-eventing.svc.cluster.local/triggers/knative-samples/hello-go/b0532795-1042-4459-898f-d63afea8307d
创建 trigger
$ cat trigger.yaml
apiVersion: eventing.knative.dev/v1
kind: Trigger
metadata:
name: hello-go
namespace: knative-samples
spec:
broker: default
filter:
attributes:
type: dev.knative.samples.helloworld
source: dev.knative.samples/helloworldsource
subscriber:
ref:
apiVersion: v1
kind: Service
name: hello-go
$ kubectl apply -f trigger.yaml创建 trigger 涉及的完整流程是：
创建了 trigger
$ kubectl -n knative-samples get trigger NAME BROKER SUBSCRIBER_URI AGE READY REASON hello-go default http://hello-go.knative-samples.svc.cluster.local/ 2m40s Truemt-broker-controller 将应用地址填充到 trigger.status
kubectl -n knative-samples get trigger hello-go -o yaml | grep subscriberUri
访问应用
$ kubectl -n knative-samples run -it curl --image=radial/busyboxplus:curl
[ root@curl-69c656fd45-7v77f:/ ]$ curl "http://broker-ingress.knative-eventing.svc.cluster.local/knative-samples/default" -X POST -H "Ce-Id: xxx" -H "Ce-Specversion: 1.0" -H "Ce-Type: dev.knative.samples.helloworld" -H
"Ce-Source: dev.knative.samples/helloworldsource" -H "Content-Type: application/json" -d '{"msg":"hello, world!"}'
[ root@curl-69c656fd45-7v77f:/ ]$ exit
$ kubectl -n knative-samples logs -l app=hello-go
2020/09/02 12:20:09 Hello World Message from received event "hello, world!"访问应用涉及的完整流程是：
访问请求发送到 broker-ingress
broker-ingress 从 broker.status 里获取 channel 地址，转发 event 到 imc-dispatcher
imc-dispatcher 从 channel.spec 里获取 subscriber 地址，转发 event 到 broker-dispatcher
broker-dispatcher 从 trigger.spec 里获取 filter 配置，对 event 进行过滤
broker-dispatcher 从 trigger.status 里获取 subscriber 地址，转发 event 到应用
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