目录
序言
三言两语，不如细心探索。
今天整理了一下Eventing 相关知识点
- Parallel
- Sequence
希望此文，能帮助读者对Knative Eventing 的这两个知识点有一个初步的了解
文章标记颜色说明：
- 黄色：重要标题
- 红色：用来标记结论
- 绿色：用来标记一级论点
- 蓝色：用来标记二级论点
1.Parallel介绍
学习Parallel 的时候，看了很多资料，其中觉得比较全面的是：
Flows - Parallel - 《Knative v1.8 Documentation》
Parallel CRD provides a way to easily define a list of branches,
each receiving the same CloudEvent sent to the Parallel ingress channel.
Typically, each branch consists of a filter function guarding the execution of the branch.
Parallel creates
Channels andSubscriptions under the hood.
总结下来，就是支持根据不同的过滤条件对事件进行选择处理
1.1 Parallel Spec
Parallel 资源定义，典型的 Parallel Spec描述如下：
-
apiVersion: messaging.knative.dev/v1alpha1
-
kind: Parallel
-
metadata:
-
name: me-odd-even-parallel
-
spec:
-
channelTemplate:
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apiVersion: messaging.knative.dev/v1alpha1
-
kind: InMemoryChannel
-
cases:
-
- filter:
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uri:
"http://me-even-odd-switcher.default.svc.cluster.local/0"
-
subscriber:
-
ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: me-even-transformer
-
- filter:
-
uri:
"http://me-even-odd-switcher.default.svc.cluster.local/1"
-
subscriber:
-
ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: me-odd-transformer
-
reply:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: me-event-display
主要包括3个部分：
channelTemplate：定义了当前 Parallel 中使用的Channel类型
cases：定义了一系列 filter 和 subscriber。对于每个条件分支：
filter：首先判断filter， 当返回事件时，调用 subscriber。filter和subscriber要求都是可访问的。- subscriber： 执行返回的事件会发生到 reply。如果 reply 为空，则发送到
spec.replyreply：定义了全局响应的目标函数。为可选配置其架构流程如下图
2.Sequence
主要学习了该文章，感谢作者大大：
Knative Eventing 之 Sequence 介绍
Sequence 是Knative Eventing中提供了一个资源模型，主要是为了支持对一个事件进行分步骤多次处理的场景。简单说，用于事件Pipeline处理。概括下来，有以下2点：
- 一种资源模型
- 事件Pipeline处理
2.1.Sequence Spec
Sequence Spec 的demo示例
-
apiVersion: messaging.knative.dev/v1alpha1
-
kind: Sequence
-
metadata:
-
name: sequencetest
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spec:
-
channelTemplate:
-
apiVersion: messaging.knative.dev/v1alpha1
-
kind: InMemoryChannel
-
steps:
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: sequencetest1
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: sequencetest2
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: sequencetest3
-
reply:
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kind: Broker
-
apiVersion: eventing.knative.dev/v1alpha1
-
name: sequencetest4
从定义中可以看出：
Sequence Spec包括3个部分：
- channelTemplate：指定了具体使用的Channel
- steps： 定义了按照顺序执行的服务，而且每个服务会对应创建Subscription。这里定义了三个步骤。每个步骤执行不同的服务
- reply：定义了最后一个step返回结果的响应目标，这一步骤是可选
2.2适用场景
Sequence 在 Knative Eventing 中提供的如下 4 种使用场景：
Broker/Trigger
级联 Sequence
面向事件处理
直接访问 Service
2.3 Broker/Trigger
该类型是最复杂的一个场景：
事件源 cronjobsource 向 Broker 发送事件，通过 Trigger 将这些事件发送到由 多个 Service 调用的 Sequence 中。
Sequence 处理完之后将结果事件发送给 Broker，并最终由另一个 Trigger 发送给
event-displayService 显示事件结果。如下图所示：
2.4 代码示例
主要分为以下几步骤，分别创建：
- knative Service
- Sequence
- Broker
- 创建事件源
- Trigger 指向 Sequence
- 结果订阅 Trigger
1.创建knative Service
创建 3 个 Knative Service，用于 Sequence 中服务处理。
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--- 第一个service -one
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apiVersion: serving.knative.dev/v1alpha1
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kind: Service
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metadata:
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name: one
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spec:
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template:
-
spec:
-
containers:
-
- image: registry.cn-hangzhou.aliyuncs.com/knative-sample/probable-summer:2656f39a7fcb6afd9fc79e7a4e215d14d651dc674f38020d1d18c6f04b220700
-
env:
-
- name: STEP
-
value:
"1"
-
-
--- 第二个service - two
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
metadata:
-
name: two
-
spec:
-
template:
-
spec:
-
containers:
-
- image: registry.cn-hangzhou.aliyuncs.com/knative-sample/probable-summer:2656f39a7fcb6afd9fc79e7a4e215d14d651dc674f38020d1d18c6f04b220700
-
env:
-
- name: STEP
-
value:
"2"
-
--- 第三个
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apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
metadata:
-
name: three
-
spec:
-
template:
-
spec:
-
containers:
-
- image: registry.cn-hangzhou.aliyuncs.com/knative-sample/probable-summer:2656f39a7fcb6afd9fc79e7a4e215d14d651dc674f38020d1d18c6f04b220700
-
env:
-
- name: STEP
-
value:
"3"
2.创建 Sequence
创建 Sequence，依次顺序执行
one->two->three这 3 个服务。将最终处理的结果发送到
broker-test中。
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apiVersion: messaging.knative.dev/v1alpha1
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kind: Sequence
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metadata:
-
name: sequence
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spec:
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channelTemplate:
-
apiVersion: messaging.knative.dev/v1alpha1
-
kind: InMemoryChannel
-
steps:
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: one
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: two
-
- ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: three
-
reply:
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kind: Broker
-
apiVersion: eventing.knative.dev/v1alpha1
-
name: broker-test
3.创建broker
创建默认的broker
kubectl label namespace default knative-eventing-injection=enabled4.创建事件源
创建事件源指向 Broker
创建 CronjobSource，它将每隔 1 分钟发送一条
{"message": "Hello Knative Sequence!"}消息到 broker-test 中。
-
apiVersion: sources.eventing.knative.dev/v1alpha1
-
kind: CronJobSource
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metadata:
-
name: cronjob-source
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spec:
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schedule:
"*/1 * * * *"
-
data:
'{"message": "Hello Knative Sequence!"}'
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sink:
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apiVersion: eventing.knative.dev/v1alpha1
-
kind: Broker
-
name: broker-test
5.Trigger 指向 Sequence
创建订阅事件类型为
dev.knative.cronjob.event的 Trigger, 用于 Sequence 进行消费处理。
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apiVersion: eventing.knative.dev/v1alpha1
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kind: Trigger
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metadata:
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name: sequence-trigger
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spec:
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filter:
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sourceAndType:
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type: dev.knative.cronjob.event
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subscriber:
-
ref:
-
apiVersion: messaging.knative.dev/v1alpha1
-
kind: Sequence
-
name: sequence
6.结果订阅 Trigger
创建订阅
samples.http.mod3的事件类型 Trigger，将 Sequence 执行的结果发送给event-displayService 进行显示。
-
apiVersion: eventing.knative.dev/v1alpha1
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kind: Trigger
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metadata:
-
name: display-trigger
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spec:
-
filter:
-
sourceAndType:
-
type: samples.http.mod3
-
subscriber:
-
ref:
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
name: event-display
-
---
-
apiVersion: serving.knative.dev/v1alpha1
-
kind: Service
-
metadata:
-
name: event-display
-
spec:
-
template:
-
spec:
-
containers:
-
- image: registry.cn-hangzhou.aliyuncs.com/knative-release/event_display:bf45b3eb1e7fc4cb63d6a5a6416cf696295484a7662e0cf9ccdf5c080542c21d
-
---
参考：
3.投票
转载：https://blog.csdn.net/weixin_36755535/article/details/128106480