Ensure that the loaded config survives an application reload

[tompave]

Pass persistent: true to Application.put_env/4, so that the new config values will survive the application load and reload events.

Documented here. As example, it's used by Mix.Config.persist/1.

[mrluc]

That makes perfect sense to me as default behavior; I want it. But I'd like to make sure I think it through, because it seems like this could be breaking to some people.

Could you describe your use case?

I ask because we're already encouraging people to use DeferredConfig from the Application.start callback, which means that the app shouldn't be missing config due to an ordinary app stop/start, so is the use case related to hot code reloading and not getting overridden by eg. app resource files?

[tompave]

Hi, thanks for the quick reply.

To be honest I don't have a use case for this. I'm using this package for a project I'm working on, I was reading the sources and I noticed that no option was passed to Application.put_env/4. It's working great in development for the moment. 👍

I just thought that this makes sense because I imagine that — as you mentioned — with the current implementation hot-code-reloading would wipe out the dynamic configuration values.