连接到另一个 Sequence 的 Sequence¶

我们将创建以下逻辑配置。我们创建了一个 PingSource，将事件馈送到 Sequence，然后获取该 Sequence 的输出并将其发送到第二个 Sequence，最后显示结果输出。

Logical Configuration

这些示例中使用的函数位于 https://github.com/knative/eventing/blob/main/cmd/appender/main.go 中。

先决条件¶

在本示例中，我们假设您已设置了 InMemoryChannel 以及 Knative Serving（用于我们的函数）。示例使用 default 命名空间，同样，如果您想部署到其他命名空间，则需要修改示例以反映这一点。

如果您想使用不同类型的 Channel，则必须修改 Sequence.Spec.ChannelTemplate 以创建适当的 Channel 资源。

设置¶

创建 Knative 服务¶

在以下命令中将 default 更改为您要创建资源的命名空间

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

---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: second
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 1"
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: third
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 2"
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: fourth
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 3"

---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: fifth
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 4"
---
apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: sixth
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/appender
          env:
            - name: MESSAGE
              value: " - Handled by 5"
---

kubectl -n default create -f ./steps.yaml

创建第一个 Sequence¶

sequence1.yaml 文件包含创建 Sequence 的规范。如果您使用的是不同类型的 Channel，则需要更改 spec.channelTemplate 以指向您所需的 Channel。

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

在以下命令中将 default 更改为您要创建 Sequence 的命名空间

kubectl -n default create -f ./sequence1.yaml

创建第二个 Sequence¶

sequence2.yaml 文件包含创建 Sequence 的规范。如果您使用的是不同类型的 Channel，则需要更改 spec.channelTemplate 以指向您所需的 Channel。

apiVersion: flows.knative.dev/v1
kind: Sequence
metadata:
  name: second-sequence
spec:
  channelTemplate:
    apiVersion: messaging.knative.dev/v1
    kind: InMemoryChannel
  steps:
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: fourth
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: fifth
    - ref:
        apiVersion: serving.knative.dev/v1
        kind: Service
        name: sixth
  reply:
    ref:
      kind: Service
      apiVersion: serving.knative.dev/v1
      name: event-display

kubectl -n default create -f ./sequence2.yaml

创建显示 Sequence 创建的事件的服务¶

apiVersion: serving.knative.dev/v1
kind: Service
metadata:
  name: event-display
spec:
  template:
    spec:
      containers:
        - image: gcr.io/knative-releases/knative.dev/eventing/cmd/event_display

在以下命令中将 default 更改为您要创建 Sequence 的命名空间

kubectl -n default create -f ./event-display.yaml

创建将 PingSource 定向到第一个 Sequence¶

这将创建一个 PingSource，它将每 2 分钟发送一次具有 {"message": "Hello world!"} 作为数据有效负载的 CloudEvent。

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

kubectl -n default create -f ./ping-source.yaml

检查结果¶

您现在可以通过检查 event-display pod 的日志来查看最终输出。

kubectl -n default get pods

然后查看 event-display pod 的日志

kubectl -n default logs -l serving.knative.dev/service=event-display -c user-container --tail=-1
☁️  cloudevents.Event
Validation: valid
Context Attributes,
  specversion: 1.0
  type: dev.knative.sources.ping
  source: /apis/v1/namespaces/default/pingsources/ping-source
  id: 29d531df-78d8-4d11-9ffd-ba24045241a9
  time: 2020-03-02T21:18:00.0011708Z
  datacontenttype: application/json
Extensions,
  knativehistory: first-sequence-kn-sequence-0-kn-channel.default.svc.cluster.local; first-sequence-kn-sequence-1-kn-channel.default.svc.cluster.local; first-sequence-kn-sequence-2-kn-channel.default.svc.cluster.local; second-sequence-kn-sequence-0-kn-channel.default.svc.cluster.local; second-sequence-kn-sequence-1-kn-channel.default.svc.cluster.local; second-sequence-kn-sequence-2-kn-channel.default.svc.cluster.local
  traceparent: 00-e5abc9de525a89ead80560b8f328de5c-fc12b64a6296f541-00
Data,
  {
    "id": 0,
    "message": "Hello world! - Handled by 0 - Handled by 1 - Handled by 2 - Handled by 3 - Handled by 4 - Handled by 5"
  }

您可以看到初始 PingSource 消息 ("Hello World!") 已通过 Sequence 中的每个步骤附加到它。