环境说明

◼ PingSource负责生成event
◼ Event由Sequence中的各Step顺次处理
  ◆各Step都运行一个appender应用
  ◆分别向收到的数据尾部附加自定义的专有数据项
◼ 最终结果发往ksvc/event-display

环境示意图

创建名称空间

# kubectl create ns sequence-demo

namespace/sequence-demo created

创建 step

steps.yaml

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: first
  namespace: sequence-demo
spec:
  template:
    spec:
      containers:
        - image: gcr.dockerproxy.com/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 0"

---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: second
  namespace: sequence-demo
spec:
  template:
    spec:
      containers:
        - image: gcr.dockerproxy.com/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 1"
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: third
  namespace: sequence-demo
spec:
  template:
    spec:
      containers:
        - image: gcr.dockerproxy.com/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 2"

创建 steps 资源

# kubectl apply -f steps.yaml

service.serving.knative.dev/first created
service.serving.knative.dev/second created
service.serving.knative.dev/third created

查看 steps 资源

# kubectl get ksvc -n sequence-demo

NAME     URL                                         LATESTCREATED   LATESTREADY    READY   REASON
first    http://first.sequence-demo.svc.wgs.local    first-00001     first-00001    True    
second   http://second.sequence-demo.svc.wgs.local   second-00001    second-00001   True    
third    http://third.sequence-demo.svc.wgs.local    third-00001     third-00001    True  

创建 event-display

event-display.yaml

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: event-display
  namespace: sequence-demo
spec:
  template:
    metadata:
      annotations:
        autoscaling.knative.dev/min-scale: "1"
    spec:
      containers:
        - image: gcr.dockerproxy.com/knative-releases/knative.dev/eventing/cmd/event_display

创建 event-display 资源

# kubectl apply -f event-display.yaml

service.serving.knative.dev/event-display created

查看 event-display 资源

# kubectl get ksvc -n sequence-demo

NAME            URL                                                LATESTCREATED         LATESTREADY           READY   REASON
event-display   http://event-display.sequence-demo.svc.wgs.local   event-display-00001   event-display-00001   True    
first           http://first.sequence-demo.svc.wgs.local           first-00001           first-00001           True    
second          http://second.sequence-demo.svc.wgs.local          second-00001          second-00001          True    
third           http://third.sequence-demo.svc.wgs.local           third-00001           third-00001           True  

创建 sequence

sequence.yaml

apiVersion: flows.knative.dev/v1
kind: Sequence
metadata:
  name: sequence
  namespace: sequence-demo
spec:
  channelTemplate:
    apiVersion: messaging.knative.dev/v1
    kind: InMemoryChannel
  steps:
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: first
        namespace: sequence-demo
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: second
        namespace: sequence-demo
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: third
        namespace: sequence-demo
  reply:
    ref:
      kind: Service
      apiVersion: serving.knative.dev/v1
      name: event-display
      namespace: sequence-demo

创建 sequence 资源

# kubectl apply -f sequence.yaml

sequence.flows.knative.dev/sequence created

查看 sequence 资源

# kubectl get sequences -n sequence-demo

NAME       URL                                                                    AGE   READY   REASON
sequence   http://sequence-kn-sequence-0-kn-channel.sequence-demo.svc.wgs.local   69s   True    

创建 PingSource

ping-source.yaml

apiVersion: sources.knative.dev/v1
kind: PingSource
metadata:
  name: ping-source
  namespace: sequence-demo
spec:
  schedule: "*/2 * * * *"
  contentType: "application/json"
  data: '{"message": "Hello world!"}'
  sink:
    ref:
      apiVersion: flows.knative.dev/v1
      kind: Sequence
      name: sequence
      namespace: sequence-demo

创建 pingsource 资源

# kubectl apply -f ping-source.yaml

pingsource.sources.knative.dev/ping-source created

查看 pingsource 资源

# kubectl get PingSource -n sequence-demo

NAME          SINK                                                                   SCHEDULE      AGE   READY   REASON
ping-source   http://sequence-kn-sequence-0-kn-channel.sequence-demo.svc.wgs.local   */2 * * * *   64s   True    

验证结果

查看 pod

# kubectl get pod -n sequence-demo

NAME                                              READY   STATUS    RESTARTS   AGE
event-display-00002-deployment-5d884ddd6f-qhwpx   2/2     Running   0          32s

查看日志

# kubectl logs event-display-00002-deployment-5d884ddd6f-qhwpx  -c user-container -n sequence-demo

☁️  cloudevents.Event
Context Attributes,
  specversion: 1.0
  type: dev.knative.sources.ping
  source: /apis/v1/namespaces/sequence-demo/pingsources/ping-source
  id: 8df28a0b-2391-405b-a369-28c23882e6af
  time: 2023-11-19T13:44:00.245632902Z
  datacontenttype: application/json
Data,
  {
    "id": 0,
    "message": "Hello world! - Handled by 0 - Handled by 1 - Handled by 2"
  }

参考文档

https://knative.dev/docs/eventing/flows/sequence/