Allow configuring OTEL_ values from any source

[srogovtsev]

This fixes #151 by exposing already existing configuration delegate.

I thought about adding some tests, but there's no good seam to verify the behavior and the code is as simple as it could be.

[nblumhardt]

Thanks for the PR @srogovtsev!

In this sink, the top-level parameters on WriteTo.OpenTelemetry() are the simple/happy path. The rest go onto OpenTelemetrySinkOptions, which I think would be the best place for this one. Adding to the options type is usually not a breaking API change, and over time it's easier to manage these than a variety of overloads.

Could the setting instead be exposed as OpenTelemetrySinkOptions.GetEnvironmentVariable perhaps? Since the accepted values are the ones documented as environment variables in the OTel docs, I think this name would be reasonable (though GetOTelConfigurationVariable or similar could also work).

[srogovtsev]

Could the setting instead be exposed as OpenTelemetrySinkOptions.GetEnvironmentVariable perhaps?

I wouldn't mind that at all, but wouldn't it be somewhat roundabout: we get a setting from OpenTelemetrySinkOptions to then modify other settings in the same object? I personally have no objections to that, just somewhat curious.

Since the accepted values are the ones documented as environment variables in the OTel docs, I think this name would be reasonable (though GetOTelConfigurationVariable or similar could also work).

I'd prefer it to say "configuration", because the whole idea of this setting is to allow reading them from places other than environment, so I would find it confusing when the option GetEnvironmentVariable is set to, let's say, AppSettings.GetString.

[nblumhardt]

wouldn't it be somewhat roundabout

Looking again, I think your way is better, since it sets up a nice clear relationship between the new option and ignoreEnvironment 👍

I'd prefer it to say "configuration"

getConfigurationVariable might be the winner? 👍

[srogovtsev]

I have renamed the delegate parameter to getConfigurationVariable, as discussed.

[srogovtsev]

Changes in this file are purely cosmetic (renaming getEnvironmentVariable to getConfigurationVariable) and can be discarded if they seem redundant

[nblumhardt]

Couple of nitpicks but otherwise LGTM!

[nblumhardt]

Thanks @srogovtsev!