Another question that is bugging me. In `ktor-server-call-logging` <https://github.com/ktorio/ktor/b...

# ktor

[Satyam Agarwal]

Another question that is bugging me. In ktor-server-call-logging
https://github.com/ktorio/ktor/blob/main/ktor-server/ktor-server-plugins/ktor-server-call-logging/jvm/src/io/ktor/server/plugins/callloging/MDCProvider.kt#L12
Here mdc entries are registered in the plugin registry, but I couldn’t find out where they are extracted again back from the plugin registry to be used (they are however used from the pluginConfig, so I don’t see why these are being registered in pluginRegistry). Is this code redundant or is there any magic that I cant see 😅 ?

[Aleksei Tirman [JB]]

That’s magic https://github.com/ktorio/ktor/blob/d147142987a69cf80227161eb10ff6546db22ea6/ktor-server/ktor-server/jvm/src/io/ktor/server/logging/Logging.kt#L36

[Satyam Agarwal]

Ah I see. but eventually, all entries are evaluated for each call and its attributes, i guess ?

So If I register my attributes in pluginRegistry, will they be automatically be applied to each call instance, thus removing the need to set them up in CallSetup hook ?

[Satyam Agarwal]

Just trying to fish out the relevance of pluginRegistry, and possible usage of it 🙂

[Aleksei Tirman [JB]]

Could you please describe what problem are you trying to solve with the pluginRegistry?

[Satyam Agarwal]

Actually, I don't really have a use case. I wasn't aware about something like pluginRegistry. So I wanted to know more about it. Seems like a good way to register attributes that needs to be provided once and evaluated per call instance.
So I wanted to know more about it, the thought process behind it.

[Aleksei Tirman [JB]]

Generally, the plugin registry is used to store instances of installed plugins.

[Aleksei Tirman [JB]]

You can store attributes in the Application.attributes if you want to share data for all calls.