feat(core): Add SpEL Function Helpers for Resolved Trigger Artifacts

[evansb]

Fixes spinnaker/spinnaker#4783
This MR adds the following helper functions to Spinnaker Pipeline Expressions

#triggerResolvedArtifact(name) gets one resolved expected artifact that matches the provided name. I used name instead of type here to make it consistent with #stage(..).

#triggerResolvedArtifactByType(type) is similar to #triggerResolvedArtifact but uses type of the artifact.

[gnarea]

Thanks for implementing this functionality @evansb! 🙇 Since the changes to the doc have already been merged, I'm wondering what's blocking the merge of this PR?

[marchello2000]

I will review today

[marchello2000]

other than the nit, LGTM happy to merge it - you can "fix" the comment before or after with a separate PR

[marchello2000]

Thanks, @evansb : FYI, there is currently an issue with expressions that doesn't inject the execution in to the expressions - someone on our team is working on the fix

[evansb]

Hi @marchello2000 , just to make sure understand that correctly, does it mean that these expressions I introduced only work if the evaluation context is the stage (because they have execution field?).

So we can interpolate inside stages but not in pipeline notifications, for instance?

[marchello2000]

Right now there is an issue where calling the expression from the stage (or anywhere) will fail, if execution isn't passed in, e.g. normally you would:
${#triggerResolvedArtifact('myArtifact')} and under the covers, orca will interpolate it to:
${#triggerResolvedArtifact(execution, 'myArtifact')}

today, this interpolation is broken for new functions so if you want it to work in, you would have to write the expression as ${#triggerResolvedArtifact(execution, 'myArtifact')} - @srekapalli is fixing this

(this is a regression from #3071)

[evansb]

Got it, thanks a lot for the explanation

[gnarea]

FYI: This doesn't work for me: spinnaker/spinnaker#5105