Provide a message explaining that metrics are disabled when running i…

[yrro]

…n the Flask development server with reloading enabled

I have to admit I'm not really sure why metrics are disabled--if you can suggest some better wording I'll update the message.

[rycus86]

You can check issue #4 for more context.
I agree it's a bit surprising when you want the opposite to happen.
Rather than overriding the HTTP endpoint, I think it may be better to log a warning when this is detected? (instead of silently bailing out there)

What do you think?

[yrro]

Makes sense to me. To be honest I have read that issue and the README a couple of times and I don't really get what's going on... the README says that with DEBUG_METRICS set & after 0.5.1, "you will get metrics for the latest reloaded code." - I don't really understand what the use case for this setting is, unless the metrics are incomplete or wrong or something like that?

[rycus86]

Sorry, I should have been clearer: I think we should log the warning here once, at startup, and just return then as before, so we don't even attempt registering the metrics endpoint that will be unavailable under the reloader anyway.

[rycus86]

I don't really understand what the use case for this setting is, unless the metrics are incomplete or wrong or something like that?

Yeah, it's been a little while ago, so I don't remember the exact details, but if I remember correctly, the metrics endpoint is somehow unavailable when you run Flask with the reloader.

[coveralls]

Coverage: 84.402% (-0.1%) from 84.526% when pulling b23d178 on yrro:debug-metrics-explainer into 73404e9 on rycus86:master.

[rycus86]

Thanks for this change! I'll merge this and release it later today if I get the chance.

[yrro]

Thanks :)