Azure-functions-host: Switch to multi-dimensional metrics

[tomkerkhove]

As of today, Azure Functions provide an individual metric per function for the same scope such as {function name} AvgDurationMs.

This means that if we have 100 functions, we'll have n * 100 metrics where n is the number of different metrics Azure Functions provides.

Describe the solution you'd like

Would be great if Azure Functions runtime would move to multi-dimensional metrics in Azure Monitor and label every metric measurement with the name of the function.

This would give the following benefits:

• Reduce the number of metrics to n, regardless of the amount of functions.
• Allow metric consumers to filter & split the metric and more easily create dashboards
• Create one alert on a given metric for all functions

All kudos go to @jcorioland

[jeffhollan]

/cc @dariagrigoriu @ahmedelnably

[tomkerkhove]

Bump