Feature request: Eventlistener should support customized podTemplate

[MartinForReal]

Expected Behavior

Event listener should accept customizable default pod template as what tekton pipeline did.
If we can add a field in CRD that would be better

Actual Behavior

Event listener is created using the default deployment template. But it doesn't comply with our schedule policy.

Additional Info

tektoncd/pipeline#1901

[MartinForReal]

/kind feature

[MartinForReal]

@bobcatfish @dibyom @vdemeester @ckadner @Tomcli

[MartinForReal]

/area api

[ncskier]

This issue sounds similar to #440. I wonder if we can address both issues in the same way?

[dibyom]

Yeah this seems like a very reasonable feature request. I'm for adding this

[dibyom]

I wonder if a podTemplate would be enough though....is there a need for customizing things such as number of replicas etc.?
Also, perhaps we might need to customize fields within the Service spec as well?

[vdemeester]

This would be really nice to have this to be able to configure "resource request" for the event-listener pod 👼

[vdemeester]

I wonder if a podTemplate would be enough though....is there a need for customizing things such as number of replicas etc.?
Also, perhaps we might need to customize fields within the Service spec as well?

That's a good point, maybe having a DeploymentTemplate that would be merged with the default (and be validated a bit differently than the default Deployment spec would work).

That said, I think we might want to consider Service and Deployment as implementation detail and try as much as we can to not make those info bubble up. This would mean, having a replicas field, and maybe a podTemplate (because in the end, it's a pod running) or maybe only part of what we are interested in the podTemplate, like limits, …

[dibyom]

From the WG discussion today:

1. We should think what adding something like a PodTemplate would mean for api compatibility...I know in Pipelines we have been trying to be careful about not adding Kubernetes primitives into the Tekton API (cc @imjasonh )

2. Also worth considering, what the exact use cases are. Do we need all of the knobs present in the Pipeline PodTemplate? Maybe we just need resourceLimits and maybe replicas?

[vdemeester]

From the WG discussion today:

1. We should think what adding something like a `PodTemplate` would mean for api compatibility...I know in Pipelines we have been trying to be careful about not adding Kubernetes primitives into the Tekton API (cc @ImJasonH )

2. Also worth considering, what the exact use cases are. Do we need all of the knobs present in the Pipeline PodTemplate? Maybe we just need `resourceLimits` and maybe `replicas`?

I do agree on both. I do prefer the approach on having the least kubernetes primitive in there. As far as I can, the only need we have right now are resource request/limits and replicas.

[MartinForReal]

We also need to add tolerations or nodeSelector