Skip to content

Latest commit

 

History

History
107 lines (83 loc) · 3.16 KB

0024-embedded-trigger-templates.md

File metadata and controls

107 lines (83 loc) · 3.16 KB
title authors creation-date last-updated status
embedded-trigger-templates
@dibyom
2020-10-01
2020-10-01
implementable

TEP-0024: Embedded TriggerTemplates

Summary

This TEP proposes an addition to the Triggers API spec to allow users to embed TriggerTemplate resources inside a Trigger/EventListener.

Motivation

Embedding a resource inside another is a popular pattern in Tekton. While being able to reference other resources has many uses e.g. resuability, embedding resources makes it simple (and less verbose) to express workflows in Tekton. This is especially true for simple use cases, examples, and documentation where reusability is less of a concern. For instance, Task specs can be embedded inside TaskRuns (see the examples).

Within a Trigger, at the moment, only bindings can be embedded while Templates always have to be referenced. Allowing embedded templates will make it easier for users to create simple Triggers as well as make our examples and documentation less verbose and easier to understand.

Goals

  • Make an additive change to the Triggers API to support embedded TriggerTemplate specs.

Non-Goals

  • Changes to the TriggerTemplate Spec itself.

Proposal

There are two changes proposed to the Trigger spec:

  1. Add an optional spec field of type TriggerTemplateSpec to a Trigger's spec.Template. Example:
template:
  spec: 
    params:
    - name: "name"
    resourceTemplates:
    - apiVersion: "tekton.dev/v1beta1"
      kind: TaskRun
      metadata:
        generateName: "pr-run-"
      spec:
        taskSpec:
          steps:
          - image: ubuntu
            script: echo "hello there $(tt.params.name)"
  1. Deprecate the name field for reffering to TriggerTemplate objects in favor of a new ref field. This is for consistency as we use usually use ref to refer to other resources (see bindings as an example). Example: 
    # DEPRECATED
template:
  name: "my-tt"
# NEW
template:
 ref: "my-tt"

Upgrade & Migration Strategy

For the name to ref change, we'll make the upgrade process backwards compatible:

  1. For the next release, we'll support both name and ref fields while marking name as deprecated.

  2. We'll use a mutating admission webhook to change name fields to ref for any newly created/updated Triggers/EventListeners.

  3. In a future release, we'll remove the name field from the spec.

References

  1. GitHub issue: tektoncd/triggers#616

  2. Embedded Bindings: https://github.com/tektoncd/community/blob/master/teps/0016-concise-trigger-bindings.md