[Feature Request] Add a replacement for dot in EnvironmentVariablesConfigurationProvider

[0x53A]

Currently EnvironmentVariablesConfigurationProvider replaces __ with :.

https://github.com/aspnet/Extensions/blob/192abfdf3e73106e40d7651eecfb621e4f78c344/src/Configuration/Config.EnvironmentVariables/src/EnvironmentVariablesConfigurationProvider.cs#L67-L70

I propose to do something similar for dot.

Use case:

I need to configure logging in an asp.net core app hosted in Azure Container Instance.

I want to set one specific logger to Trace, so I need to set the configuration key Logging:LogLevel:Company.Namespace.MyCustomMiddleware = Trace.

Locally on my windows PC I can run
set Logging__LogLevel__Company.Namespace.MyCustomMiddleware=Trace
and everything works.

When I try to do it in Azure App Service, it doesn't allow me to create the container, even though it is a windows container:

Request: Please add a replacement for ., similar to :.

Workaround: I can do a code change to change the name of the logger, this works as long as it is first party code, not third party.

[analogrelay]

Putting in the list of possible 5.0 candidates (no guarantees!). The fact that logging can't be fully configured via environment variables because of this is a compelling reason to consider this.

[analogrelay]

Triage: We think the right approach here is to see if App Service can resolve this blockage. Adding a new replacement pattern would be extremely breaking.

[analogrelay]

Turns out macOS and Linux don't support . in env vars either though, so we may need to find a deeper solution for the Logging problem specifically. The problem is it's also breaking to use a replacement token in Logging because logger names can be any string (they tend to be based on type names but don't have to be).

[ericstj]

There appear to be lots of characters that aren't allowed here. Here are some that I tried: #^+&|;, does this require some generic escaping rule?