Enable TriggerBindings to validate requests

[khrm]

This PR resolves the issue #45.
It assumes that a task has been defined which can validate requests.
That task will receive header and payload as params.
Before the creation of resources, task will be called alongwith serviceaccount
which has github-secret used to create webhook.
Assumption:

1. Task is defined in such a way that it can use headers and payload received as params.
2. Apart from serviceaccount, payload and headers, task doesn't need anything else.
3. Task gives us non zero exit if validation failed. A sample task and main.go is provided.

PS: This is still a work in progress. Need to test out further. Will do on Tuesday as Monday is holiday.

Changes

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Release Notes

- API changes: Added Validate Trigger Struct
- Any changes in behavior: Factor-out execute trigger to run concurrently.

[akihikokuroda]

This is not a part of the assumptions but I believe that it is an useful capability.

Would you add functions that set params into the event listener and pass them to the validation task? Otherwise the param values must be hard coded into the task and task is not reusable.

Use case: I specify the secret name (that has the secret key of the github) when I create the eventlistener and the secret name is passed to the validation task as one of the params so that the task can mount the secret.

[khrm]

Good idea, will add that.

[dibyom]

I really like the approach especially the fact that we are reusing tasks and taskruns!! Added some comments on the polling approach for checking if the taskrun is complete. In addition, I'd like to see some basic docs around the TriggerValidate type as well as an example showing it in action. But overall, looking good 😃

[khrm]

@dibyom I feel second option as better. I want to avoid resources. I am changing it to that.

[dibyom]

@khrm cool, I like @vtereso 's idea as well:

Joining the array on space or some other delimiter was what I meant behind flattening. If we are limited by arrays, maybe this is preferable?

I do agree at the moment, resources are probably not we want but later when we are done with all the cool resource extensibility stuff, it is something we could consider using

[khrm]

I do agree at the moment, resources are probably not we want but later when we are done with all the cool resource extensibility stuff, it is something we could consider using

Yes, let's wait for resource extensibility. For now, I have done json encoding. Will update the docs with that instruction.

[dibyom]

Looks good to me. Holding so that @vtereso can take another look 👼

/lgtm
/hold

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[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dibyom, khrm, vtereso

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[vtereso]

/hold cancel