Trigger: add customized fields into cloudevent extension after the event passes a trigger filter

[xiaoajlszt]

Problem
broker --> trigger1 --> app --> ...
--> trigger2 --> app --> ...
--> trigger3 --> app --> ...

Similar to the event delivery process above, since we reuse apps (three apps are actually one app), we need to know the location of the event (that is, which app in the workflow) based on some fields in the event. Then we obtain the corresponding configuration according to the location to process the event, and continue to deliver the event.

So I hope to add customized fields into cloudevent extension after the event passes a trigger filter. Maybe You can add a kv map in the trigger spec. thx!

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[pierDipi]

For sources, we have something similar to what you're describing https://knative.dev/docs/eventing/sources/apiserversource/reference/#cloudevent-overrides but it's not based on some fields in the event.

Can you expand a bit more on the based on some fields in the event with a few examples?

[xiaoajlszt]

For example, when we handle an abnormal event, we usually need to go through multiple processing steps, which form a workflow.

We may reuse some steps (these steps are run by the same pod, while each step has its own configuration).

During the delivery of events, we save the current step's position(in the workflow) in the cloudevent extension, and the pod can obtain the configuration of current step by the position in the cloudevent.

[Cali0707]

Hey @xiaoajlszt - in your use case, do you send the new event back to the broker by replying to the original request sent from the trigger, or is it a fully new request to the broker?