Tekton trigger flow from github - tekton

Question

I am learning Tekton (for business), coming from github actions (private).
The Tekton docs (or any other tutorial I could find) have instructions on how to automatically start a pipeline from a github push. Basically they all somewhat follow the below flow: (I am aware of PipelineRun/TaskRun etc)
Eventlistener - Trigger - TriggerTemplate - Pipeline
All above steps are basically configuration steps you need to take (and files to create and maintain), one easier than the other but as far as I can see they also need to be taken for every single repo you're maintaining. Compared to github actions where I just need 1 file in my repo describing everything I need this seems very elaborate (if not cumbersome).
Am I missing something ? Or is this just the way to go ?
Thanks !

Answer 1

they also need to be taken for every single repo you're maintaining
You're mistaken here.
The EventListener receives the payload of your webhook.
Based on your TriggerBinding, you may map fields from that GitHub payload, to variables, such as your input repository name/URL, a branch or ref to work with, ...
For GitHub push events, one way to do it would be with a TriggerBinding such as the following:
apiVersion: triggers.tekton.dev/v1alpha1
kind: TriggerBinding
metadata:
name: github-push
spec:
params:
- name: gitbranch
value: $(extensions.branch_name) # uses CEL interceptor, see EL below
- name: gitrevision
value: $(body.after) # uses body from webhook payload
- name: gitrepositoryname
value: $(body.repository.name)
- name: gitrepositoryurl
value: $(body.repository.clone_url)
We may re-use those params within our TriggerTemplate, passing them to our Pipelines / Tasks:
apiVersion: triggers.tekton.dev/v1alpha1
kind: TriggerTemplate
metadata:
name: github-pipelinerun
spec:
params:
- name: gitbranch
- name: gitrevision
- name: gitrepositoryname
- name: gitrepositoryurl
resourcetemplates:
- apiVersion: tekton.dev/v1beta1
kind: PipelineRun
metadata:
generateName: github-job-
spec:
params:
- name: identifier
value: "demo-$(tt.params.gitrevision)"
pipelineRef:
name: ci-docker-build
resources:
- name: app-git
resourceSpec:
type: git
params:
- name: revision
value: $(tt.params.gitrevision)
- name: url
value: $(tt.params.gitrepositoryurl)
- name: ci-image
resourceSpec:
type: image
params:
- name: url
value: registry.registry.svc.cluster.local:5000/ci/$(tt.params.gitrepositoryname):$(tt.params.gitrevision)
- name: target-image
resourceSpec:
type: image
params:
- name: url
value: registry.registry.svc.cluster.local:5000/ci/$(tt.params.gitrepositoryname):$(tt.params.gitbranch)
timeout: 2h0m0s
Using the following EventListener:
apiVersion: triggers.tekton.dev/v1alpha1
kind: EventListener
metadata:
name: github-listener
spec:
triggers:
- name: github-push-listener
interceptors:
- name: GitHub push payload check
github:
secretRef:
secretName: github-secret # a Secret you would create (option)
secretKey: secretToken # the secretToken in my Secret matches to secret configured in GitHub, for my webhook
eventTypes:
- push
- name: CEL extracts branch name
ref:
name: cel
params:
- name: overlays
value:
- key: truncated_sha
expression: "body.after.truncate(7)"
- key: branch_name
expression: "body.ref.split('/')[2]"
bindings:
- ref: github-push
template:
ref: github-pipelinerun
And now, you can expose that EventListener, with an Ingress, to receive notifications from any of your GitHub repository.