How important is it to support runtime configuration change?

[hkupty]

Penna supports runtime configuration change at the moment. This means that, if you have access to the the ConfigManager, you can, during runtime, change a certain logger's (or a hierarchy of loggers) level.

However, if people feel like this is not important (i.e. it is cheap enough to update a config and restart the application), then removing this feature can greatly simplify the code.

Although I'm inclined to keep the feature, I'd like to hear what people think about it before making stronger commitments.

The implications of keeping the feature are:

• penna-yaml-config would need to support file watch (i.e. if penna's configuration is stored as a ConfigMap in kubernetes, they'd be automatically propagated upon update);
• The internal replace/update API would need to be reworked/stabilized (most likely a hard replace instead of an update);
• Given the API is shared between dev and core, maybe it should provide the default implementation which, if explicitly imported, could provide the runtime capabilities to manage the log levels, easing the burden on dev.

The implications of removing the feature are:

• The storage and the logger are going to be much simpler in code as there's no runtime config change.

[desiderantes]

Would say keep it because it's very common to have to change logger levels in something like a Spring App with Actuator (for example, Spring Boot Admin offers a nice gui to do that), and also to do things like on error threshold >= value, change log level for package.