TektonCD Demo a preview URL on PR

This will demo a preview URL for PR changes.

It installs a TektonCD Triggers Eventlistener to listen when new PR is created and deploy a PipelineRun which would :

comment-first: Set GitHUB Status and give a Tekton-Dashboard URL to follow the build
build - build the Dockerfile, which has a simple golang web server based on echo to server the static files.
push - push the image to the openshfit internal registry
deploy - deploy the imge to its own deployment (suffixed with the git sha commit of the change) and expose it publicaly with a route.
comment-last - Post the URL back on the Github issue comment and set the status as successfull.

Installs

Install TektonCD Pipelines and Triggers.

use the install.sh script on your cloud, it assumes you have your github token set in your /.gitconfig as :

[github]
	oauth-token = TOKEN

Configure your webhook to push PR events to your eventlistenner route, get your endpoint url with :

https://$(oc get route el-preview-url -o jsonpath='{.spec.host}')