asweet-confluent
I recently noticed that Elixir’s Logger defaults its primary log level to :debug when no :logger, :level application configuration is present.
In Logger.App, the default ultimately comes from this line:
Application.get_env(:logger, :level, :debug)
Would something like :info or even :warning be a more reasonable default?
I bring this up because I ran into an issue where someone changed our log level from :info to :warn and it resulted in log spam. While Logger is pretty good about changing :warn into :warning under the hood, we have some code that goes through :logger.set_handler_config, which doesn’t have that check and just returns an error. If you don’t catch that, you’re left on :debug.
I’m thinking about how to prevent this situation in the future, and while I can add error handling around every call into :logger, I don’t see a good way to structurally prevent this sort of thing from happening again - it seems like it just comes down to “remember to do it right”, which makes me think this is a footgun in Logger rather than something I should be solving.
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hauleth
Yes, it would be more reasonable default to use
:infoby default, but because of backward compatibility it needs to be:debug.jhogberg
The way to structurally prevent this from happening is having
:debugas a default: you noticed it, didn’t you?NobbZ
I hate logging systems that hide messages by default from me.
When initially developing I want to see all the messages without having to mind about configuration.
mat-hek
In Membrane, we have a
debug_verbose: booleanflag set via config, defaulting tofalse, and a correspondingdebug_verbosemacro. It’s intended for logs that are only useful for debugging the library itself, so we decided to hide them from the user by default.For the regular debugs, I’d prefer if they were also disabled by default, as they’re intended for, well, debugging
asweet-confluent
What’s the bar for breaking compatibility? There’s some precedent for doing so when it prevents confusion:
Changing the default log level to something safer for production doesn’t seem like a huge stretch by comparison.
It would be nice to have a deprecation path. Can
Loggerreliably distinguish between an explicitly configured log level and falling back to its implicit:debugdefault? If so, it seems like reliance on the implicit default could first be deprecated, giving users who actually want:debuga chance to configure it explicitly.Another interesting data point: Phoenix’s default production configuration sets the level to
:info. If Phoenix is as widely used as I think it is, I suspect this masks the problem since most people never have to deal with the consequences ofLogger’s defaults.hauleth
Yeah, I know, that is my work.
I 100% agree with you that default of
:debugis wrong and should be changed, ideally to match Erlang’s:notice, as it would make a lot of stuff much easier.Unfortunately - no. If that would be possible then I would propose that in the first place, but there is no way to detect that.
I believe that the default configuration of logger should match the production environment, not dev. Dev environment is form of special environment, and accidental leakage of private data (which may be logged in debug logs) is bigger issue IMHO.