may be trying changing the name of backend?

config :logger,
  backends: [{LoggerFileBackend, :info_log},
             {LoggerFileBackend, :error_log}]

config :logger, :info_log,
  path: "/path/to/info.log",
  level: :info

config :logger, :error_log,
  path: "/path/to/error.log",
  level: :error

Still works fine only for error logs.

Looking at the docs https://github.com/onkel-dirtus/logger_file_backend, I think that adding metadata_filter that corresponds to {LoggerFileBackend, :info} should work:

config :logger, :info,
  path: "info.log",
  level: :info,
  metadata_filter: [application: :info]

wouldn’t that force you add a metadata for each log message?
as in

Logger.info("log log log",application: :info)

Now it doen’t even create the files.

@ayhan.rashidov looks like you caught a bug.

your config is from their github.
https://github.com/onkel-dirtus/logger_file_backend#application-config-for-multiple-log-files

It seems to work fine using the third example.

# in a config file:
config :logger,
  backends: [{LoggerFileBackend, :device_1}]

config :logger, :device_1
  path: "/path/to/device_1.log",
  level: :debug,
  metadata_filter: [device: 1]

# Usage:
# anywhere in the code:
Logger.info("statement", device: 1)

Yes, seems my assumption is wrong :(. Seems that metadata_filter works only when you add the metadata directly in the log message.

err, @ayhan.rashidov I am wrong, this is not a bug. Actually, the data you see is 100% correct. When you mention logging level info all the logs that are less or equal to the verbosity will be logged regardless of the backend.

Verbosity levels:
debug > info > warn > error

so “info” level will log all info, warn and error logs and “warn” will log all warn & error logs ., etc.

if you really want only error logs to a file and only info logs in one log ( I would advice against it) . you can use metadata.

config :logger,
  backends: [{LoggerFileBackend, :info},
             {LoggerFileBackend, :error}]

config :logger, :info,
  path: "/path/to/info.log",
  level: :info,
  metadata_filter: [level: :info]

config :logger, :error,
  path: "/path/to/error.log",
  level: :error,
  metadata_filter: [level: :error]

and you may use like –

Logger.info("This is info log",level: :info)
Logger.error("This is info log",level: :error)