OpenShift 4.3 之Knative-Tutorial(6) Eventing之Channel和Subscription
文章目录
- 概念
- 操作
- 参考
概念
Knative Eventing中的Channel和Subscription类似JMS消息体系中的Topic/Subscribe机制。Event Source是消息的发布者（类似JMS的Publisher），Channle是传送消息的通道（类似JMS的Topic），而Subscription通过订阅Channel获取到相关的Event，并且使用Knative Serving的服务处理消息。
操作
- 创建如下内容的channel.yaml文件，其中定义了名为eventinghello-ch的Channel类型的对象。
apiVersion: messaging.knative.dev/v1alpha1
kind: Channel
metadata:
name: eventinghello-ch
- 执行命令生成Channel对象，然后查看eventinghello-ch状态为READY=true。
$ oc -n knativetutorial apply -f channel.yaml
$ oc -n knativetutorial get channel
NAME READY REASON URL AGE
eventinghello-ch True http://eventinghello-ch-kn-channel.knativetutorial.svc.cluster.local 34s
$ oc -n knativetutorial get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
eventinghello-ch-kn-channel ExternalName <none> imc-dispatcher.knative-eventing.svc.cluster.local <none> 40s
- 创建如下内容的event-source.yaml文件，其中定义了名为my-cjs的CronJobSource类型的对象，它每2秒产生一次事件。事件发送目标Sink为eventinghello-ch的Channel。
apiVersion: sources.eventing.knative.dev/v1alpha1
kind: CronJobSource
metadata:
name: my-cjs
spec:
schedule: "*/2 * * * *"
data: '{"message": "From CronJob Source"}'
sink:
ref:
apiVersion: messaging.knative.dev/v1alpha1
kind: Channel
name: eventinghello-ch
- 执行命令生成CronJobSource对象，然后查看my-cjs状态为READY=true。说明：如果接收事件的目标Sink没有Ready，那么my-cjs的状态也不会Ready。
$ oc -n knativetutorial apply -f event-source.yaml
cronjobsource.sources.eventing.knative.dev/event-greeter-cronjob-source created
$ oc -n knativetutorial get cronjobsources
NAME READY AGE
my-cjs True 76s
$ oc -n knativetutorial get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
cronjobsource-my-cjs-bf3f1b8f-fc05-46d0-ae5c-a5bd9c7377b0 1/1 1 1 44m
- 分别创建eventing-helloa-sink.yaml和eventing-hellob-sink.yaml文件，内容如下。它们分别定义了名为eventinghelloa和eventinghellob的Service。
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: eventinghelloa
spec:
template:
metadata:
name: eventinghelloa-v1
annotations:
autoscaling.knative.dev/target: "1"
spec:
containers:
- image: quay.io/burrsutter/eventinghello:0.0.1
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
name: eventinghellob
spec:
template:
metadata:
name: eventinghellob-v1
annotations:
autoscaling.knative.dev/target: "1"
spec:
containers:
- image: quay.io/burrsutter/eventinghello:0.0.1
- 执行命令，创建eventinghelloa和eventinghellob服务。然后查看和eventinghelloa和eventinghellob相关的Deployment和Serivce。
$ oc apply -n knativetutorial -f eventing-helloa-sink.yaml
$ oc apply -n knativetutorial -f eventing-hellob-sink.yaml
$ oc -n knativetutorial get deployment
NAME READY UP-TO-DATE AVAILABLE AGE
cronjobsource-my-cjs-bf3f1b8f-fc05-46d0-ae5c-a5bd9c7377b0 1/1 1 1 44m
eventinghelloa-v1-deployment 0/0 0 0 24m
eventinghellob-v1-deployment 0/0 0 0 24m
$ oc -n knativetutorial get svc
NAME TYPE CLUSTER-IP EXTERNAL-IP PORT(S) AGE
eventinghello-ch-kn-channel ExternalName <none> imc-dispatcher.knative-eventing.svc.cluster.local <none> 53m
eventinghelloa ExternalName <none> kourier-internal.knative-serving-ingress.svc.cluster.local <none> 12s
eventinghelloa-v1 ClusterIP 172.30.177.109 <none> 80/TCP 22s
eventinghelloa-v1-private ClusterIP 172.30.210.190 <none> 80/TCP,9090/TCP,9091/TCP,8022/TCP 22s
eventinghellob ExternalName <none> kourier-internal.knative-serving-ingress.svc.cluster.local <none> 11s
eventinghellob-v1 ClusterIP 172.30.116.241 <none> 80/TCP 21s
eventinghellob-v1-private ClusterIP 172.30.45.121 <none> 80/TCP,9090/TCP,9091/TCP,8022/TCP 21s
- 创建eventing-helloa-sub.yaml和eventing-hellob-sub.yaml文件，内容分别如下。他们分别定义了名为eventinghelloa-sub和eventinghellob-sub的Subscription。这两个Subscription都是从名为eventinghello-ch的Channel获取消息，只不过一个用名为eventinghelloa的Service处理，另一个用名为eventinghellob的Service处理。
apiVersion: messaging.knative.dev/v1alpha1
kind: Subscription
metadata:
name: eventinghelloa-sub
spec:
channel:
apiVersion: messaging.knative.dev/v1alpha1
kind: Channel
name: eventinghello-ch
subscriber:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: eventinghelloa
apiVersion: messaging.knative.dev/v1alpha1
kind: Subscription
metadata:
name: eventinghellob-sub
spec:
channel:
apiVersion: messaging.knative.dev/v1alpha1
kind: Channel
name: eventinghello-ch
subscriber:
ref:
apiVersion: serving.knative.dev/v1
kind: Service
name: eventinghellob
- 执行命令，分别创建名为eventinghelloa-sub和eventinghellob-sub的Subscription，然后查看它们的状态变为READY=True。
$ oc -n knativetutorial apply -f eventing-helloa-sub.yaml
$ oc -n knativetutorial apply -f eventing-hellob-sub.yaml
$ oc -n knativetutorial get subscriptions.messaging.knative.dev
NAME READY REASON AGE
eventinghelloa-sub True 7m11s
eventinghellob-sub True 7m11s
- 在控制台查看运行情况。可以看到eventinghelloa和eventinghellob的实例数会在0和1之间变化。
- 执行命令，清理环境。
oc -n knativetutorial delete -f channel.yaml
oc -n knativetutorial delete -f event-source.yaml
oc -n knativetutorial delete -f eventing-helloa-sink.yaml
oc -n knativetutorial delete -f eventing-hellob-sink.yaml
oc -n knativetutorial delete -f eventing-helloa-sub.yaml
oc -n knativetutorial delete -f eventing-hellob-sub.yaml
参考
- https://github.com/RedHatWorkshops/knative-on-ocp4/blob/master/6.AddingChannelsAndSubscriptions.md