Update istio mapped metrics

[bobbytables]

Updates mapped metrics to use the new names in the templated Prometheus handler in Istio 1.0.

What does this PR do?

Istio updated their Prometheus handler config in 1.0 that changes the names of the metrics. This project is using the older defaulted names from 0.8 and when upgrading to Istio 1.0 this breaks.

Obviously this change is not backwards compatible with 0.8, but moving forward this change helps not go down the rabbit hole that we just went down.

Here is where the metric name changed: https://github.com/istio/istio/blob/master/install/kubernetes/helm/istio/charts/mixer/templates/config.yaml#L455

The change was made in this commit: istio/istio@f883fbf

Motivation

Our graphs broke in DataDog for Istio related metrics when upgrading to Istio 1.0

[gmmeyer]

Hey @bobbytables! Thanks a lot for your contribution! This PR is pretty good but we need to remain compatible with prior versions of istio. Can you update the map to include both? Can you also update the tests so that it tests v1.0 as well as the prior version?

[bobbytables]

Hey @bobbytables! Thanks a lot for your contribution! This PR is pretty good but we need to remain compatible with prior versions of istio. Can you update the map to include both? Can you also update the tests so that it tests v1.0 as well as the prior version?

Yeah I was being lazy 😛 I'll add those right now.

[bobbytables]

Tbh I don't write python and not sure where to start to support both. It's mostly the pytest that is messing with me and don't quite have time to learn..

[shraykay]

I'll assist! (bobby's coworker)

[gmmeyer]

Thank you! 😄

If you have any questions I'm happy to help!

[gmmeyer]

Hey @bobbytables @shraykay!

Thanks again for this contribution, it's really great. We were about to investigate whether there were metric changes with 1.0 when you submitted this.

This is something we wanna get out asap. If you want any help on it we're very happy to help. If you're on our public slack you can reach out to me there (greg.meyer) and I can help you. Otherwise, you can join our public slack.

If you'd like us to take over this Pull Request, I am also happy to do that.

[shraykay]

Will take a stab at this today, sorry for the delay!

[bobbytables]

@gmmeyer @shraykay did the rest.

[gmmeyer]

looks good to me! Thank you both very much!!