Tekton YAML TriggerTemplate - string substitution - triggers

Question

I have this kind of yaml file to define a trigger
`
apiVersion: triggers.tekton.dev/v1alpha1
kind: TriggerTemplate
metadata:
name: app-template-pr-deploy
spec:
params:
- name: target-branch
- name: commit
- name: actor
- name: pull-request-number
- name: namespace
resourcetemplates:
- apiVersion: tekton.dev/v1alpha1
kind: PipelineRun
metadata:
generateName: app-pr-$(tt.params.actor)-
labels:
actor: $(tt.params.actor)
spec:
serviceAccountName: myaccount
pipelineRef:
name: app-pr-deploy
podTemplate:
nodeSelector:
location: somelocation
params:
- name: branch
value: $(tt.params.target-branch)
** - name: namespace
value: $(tt.params.target-branch)**
- name: commit
value: $(tt.params.commit)
- name: pull-request-number
value: $(tt.params.pull-request-number)
resources:
- name: app-cluster
resourceRef:
name: app-location-cluster
`
The issue is that sometime target-branch is like "integration/feature" and then the namespace is not valid
I would like to check if there is an unvalid character in the value and replace it if there is.
Any way to do it ?
Didn't find any valuable way to do it beside creating a task to execute this via shell script later in the pipeline.

Answer 1

This is something you could do from your EventListener, using something such as:
apiVersion: triggers.tekton.dev/v1alpha1
kind: EventListener
metadata:
name: xx
spec:
triggers:
- name: demo
interceptors:
- name: addvar
ref:
name: cel
params:
- name: overlays
value:
- key: branch_name
expression: "body.ref.split('/')[2]"
bindings:
- ref: your-triggerbinding
template:
ref: your-triggertemplate
Then, from your TriggerTemplate, you would add the "branch_name" param, parsed from your EventListener.
Note: payload from git notification may vary. Sample above valid with github. Translating remote/origin/master into master, or abc/def/ghi/jkl into ghi.

Answer 2

I've created a separate task that is doing all the magic I needed and output a valid namespace name into a different variable.
Then instead of use namespace variable, i use valid-namespace all the way thru the pipeline.
apiVersion: tekton.dev/v1beta1
kind: Task
metadata:
name: validate-namespace-task-v1
spec:
description: >-
This task will validate namespaces
params:
- name: namespace
type: string
default: undefined
results:
- name: valid-namespace
description: this should be a valid namespace
steps:
- name: triage-validate-namespace
image: some-image:0.0.1
script: |
#!/bin/bash
echo -n "$(params.namespace)" | sed "s/[^[:alnum:]-]/-/g" | tr '[:upper:]' '[:lower:]'| tee $(results.valid-namespace.path)
Thanks