PROPOSAL: Add metrics to Polly

We are aiming to get some traction into getting metrics into Polly, a major milestone for the project.

Published to the wiki is an initial overview of the questions that we face (and some options for answers) :

• How should we structure events?
• What information should be included?
• How do we layer the architecture to provide flexibility to target multiple dashboards, rather than tie ourselves into a particular one?
• What kind of metrics/stats do we want?
• What metrics should we provide for the combined-strategy PolicyWrap?

The early-stage proposal is a series of ideas and questions.

We are also working bottom-upwards to sketch out solutions - for exploration/critique - in code.

We would love to hear community views on what would be important to you in metrics - what you want to see; how you think it should be done.

(comments equally welcome here, or comments/questions in the slack channel on the same topic)

[dhabierre]

Hi.

I am interesting in Polly metrics.

Any feedback about the implementtaion status, perthaps an alpha version? Do you have an approximate release date?

Thank you.

[reisenberger]

@lalitkale Yes, I think this is exactly what Polly should do. I’ve not had time to write up a revised proposal, but with the official deprecation of Hystrix Dashboard (and no ongoing support of Hystrix), coupled with the appearance of https://www.app-metrics.io/, Polly should abandon the Rx/Hystrix route and very likely target App-Metrics. App-Metrics looks very good: I read most of the codebase earlier in the year and see no reason why Polly metrics couldn’t target it.

The missing piece is emitting events from Polly policies in a way that can both be funnelled to App-Metrics and can support the integrated .NET Core logging requirements of IHttpClientFactory. My thinking is that policies should emit events (event streams) which are entirely generic, not tied to any particular event sink. Different sinks (App-Metrics; ILogger; others …) would then be pluggable subscribers. Deep policy event logging directly to ILogger is the missing part of the collaboration we did on Polly with the Microsoft ASP.NET teams earlier this year.