Add trigger name to slack notification about cloud-build-notifiers

[LOZORD]

Hi all! We on Cloud Build are aware of this need but want to have a standardized implementation for all notifiers, so I filed #95. We're currently waiting on our PM to share a doc in this repo for this set of features. I can't give a timeline, but I was told Soon ™️ . The implementation will be open to the community to code up.

[jrissler]

+1 this is really useful project. This feature would be ultra useful - otherwise given you have multiple apps being triggered doesn't appear to be a way to distinguish them.

[LOZORD]

You're welcome 😄 I totally agree - for silly reasons we don't include the trigger name in the Pub/Sub payload (or Build resource for that matter). Until we provide the trigger name in the payload or provide it as an available substitution, the best alternative is to stick a GCB gRPC (or JSON) client in the notifier and call GetBuildTrigger, which should include the trigger name.

Please feel free to send a PR for this functionality as others would definitely benefit!

[bouk]

PR submitted #91

[vicpadilla]

You can use {{.Build.Substitutions.TRIGGER_NAME}} in the template to get the trigger name.