PROPOSAL: Add metrics to Polly

[reisenberger]

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]

@dhabierre. Thank you for your interest. At the moment there is no eta for this feature (it is a major piece of work), and no alpha version. I have a full schedule until mid August, but will aim to assess next major items for Polly then unless I get any time earlier.

[lalitkale]

@reisenberger can you check possibility of using https://www.app-metrics.io/ for metrics work. App-metrics also support various data sourcesincluding Prometheus. Also, it has pre-existing grafana dashboard. That way, we don't need to do big legwork for adopting Metrics. It also fits with .NET core and Polly's Integration with HTTPClientFactory and overall microservices space. What are your thoughts.

[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.

[Kavignon]

@reisenberger What's the current status for Polly metrics?

[reisenberger]

Sadly I have not been able to get any time on this since last asked and can't envisage doing so at the moment. Unfortunately my current paid work is not overlapping with this, and I can't justify the unpaid hours.

(Which is not for want of continuing to donate unpaid hours to Polly in total - on many other features, and on user support.)

[Kavignon]

@reisenberger How could I get started to help out in this project?

[reisenberger]

@Kavignon . If the question is about contributing to Polly in general: we tag suitable issues with the up-for-grabs label. There aren't many at present, but 'watch' the project and more are likely to come up.

If the question is about metrics: the next best step would be for I or a community member to come up with enough of a proposal / proof-of-concept to kick-start some traction (as in eg here).

[reisenberger]

This is not a feature that I am able to deliver on an unpaid basis at present.

At the moment, I am not in a position to take on any extra paid work. However, if any organisation does want to fund this work at some future date, please feel free to contact me off-github (my email address is in my github profile), and I can advise further at that time.