Fix arity for template in eventlistener triggers

[madbence]

Changes

I think a inside an EventListener, you can only specify a single TriggerTemplate, eg. the following works:

apiVersion: triggers.tekton.dev/v1beta1
kind: EventListener
metadata:
  name: my-listener
spec:
  triggers:
    - bindings:
        - ref: my-binding
      template:
        ref: my-template

But this won't:

apiVersion: triggers.tekton.dev/v1beta1
kind: EventListener
metadata:
  name: my-listener
spec:
  triggers:
    - bindings:
        - ref: my-binding
      template:
        - ref: my-template
        - ref: my-template

I've got this error when I tried to apply it:

admission webhook "webhook.triggers.tekton.dev" denied the request: mutation failed: cannot decode incoming new object: json: cannot unmarshal array into Go struct field EventListenerTrigger.spec.triggers.template of type v1beta1.TriggerSpecTemplate

(the same happened for both triggers.tekton.dev/v1beta1 and triggers.tekton.dev/v1alpha1)

I'm definitely not an expert in tekton internals, but I found the following definitions, and it looks like that only a single TriggerTemplate is supported:

triggers/pkg/apis/triggers/v1alpha1/event_listener_types.go

Lines 87 to 102 in 7f0594e

	type EventListenerTrigger struct {
	Bindings []*EventListenerBinding `json:"bindings,omitempty"`
	Template *EventListenerTemplate `json:"template,omitempty"`
	TriggerRef string `json:"triggerRef,omitempty"`
	// +optional
	Name string `json:"name,omitempty"`
	Interceptors []*EventInterceptor `json:"interceptors,omitempty"`
	// ServiceAccountName optionally associates credentials with each trigger;
	// more granular authorization for
	// who is allowed to utilize the associated pipeline
	// vs. defaulting to whatever permissions are associated
	// with the entire EventListener and associated sink facilitates
	// multi-tenant model based scenarios
	// +optional
	ServiceAccountName string `json:"serviceAccountName,omitempty"`
	}

triggers/pkg/apis/triggers/v1beta1/event_listener_types.go

Lines 100 to 115 in 7f0594e

	type EventListenerTrigger struct {
	Bindings []*EventListenerBinding `json:"bindings,omitempty"`
	Template *EventListenerTemplate `json:"template,omitempty"`
	TriggerRef string `json:"triggerRef,omitempty"`
	// +optional
	Name string `json:"name,omitempty"`
	Interceptors []*EventInterceptor `json:"interceptors,omitempty"`
	// ServiceAccountName optionally associates credentials with each trigger;
	// more granular authorization for
	// who is allowed to utilize the associated pipeline
	// vs. defaulting to whatever permissions are associated
	// with the entire EventListener and associated sink facilitates
	// multi-tenant model based scenarios
	// +optional
	ServiceAccountName string `json:"serviceAccountName,omitempty"`
	}

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[tekton-robot]

Hi @madbence. Thanks for your PR.

I'm waiting for a tektoncd member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[savitaashture]

/ok-to-test

[savitaashture]

/lgtm

[tekton-robot]

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