rails loggers调试日志

Question

I've inheritted a medium sized Rails app with lots of different logging approaches spread across the codebase. It's a bit of a mess and I'm lost why some logs are outputed and why some not.

Is there a way for the loggers to "announce themselves"/log some status information when being created? In a similar way to what logback does when you set debug="true"

SLF4J: Class path contains multiple SLF4J bindings.
SLF4J: Found binding in [jar:file:/Users/aleksander.sumowski/.m2/repository/ch/qos/logback/logback-classic/1.2.3/logback-classic-1.2.3.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: Found binding in [jar:file:/Users/aleksander.sumowski/.m2/repository/org/slf4j/slf4j-log4j12/1.6.1/slf4j-log4j12-1.6.1.jar!/org/slf4j/impl/StaticLoggerBinder.class]
SLF4J: See http://www.slf4j.org/codes.html#multiple_bindings for an explanation.
11:28:33,076 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback-test.xml]
11:28:33,076 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Could NOT find resource [logback.groovy]
11:28:33,076 |-INFO in ch.qos.logback.classic.LoggerContext[default] - Found resource [logback.xml] at [file:/Users/aleksander.sumowski/projects/insurance/car-insurance-aggregator/resources/logback.xml]
11:28:33,168 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - Will scan for changes in [file:/Users/aleksander.sumowski/projects/insurance/car-insurance-aggregator/resources/logback.xml]
11:28:33,168 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - Setting ReconfigureOnChangeTask scanning period to 1 seconds
11:28:33,172 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.ConsoleAppender]
11:28:33,175 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [STDOUT]
11:28:33,179 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
11:28:33,214 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - About to instantiate appender of type [ch.qos.logback.core.rolling.RollingFileAppender]
11:28:33,218 |-INFO in ch.qos.logback.core.joran.action.AppenderAction - Naming appender as [FILE]
11:28:33,225 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy@1006624255 - Will use gz compression
11:28:33,228 |-INFO in c.q.l.core.rolling.TimeBasedRollingPolicy@1006624255 - Will use the pattern log/archive/car-insurance-aggregator.%d{yyyy-MM-dd}.log for the active file
11:28:33,231 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - The date pattern is 'yyyy-MM-dd' from file name pattern 'log/archive/car-insurance-aggregator.%d{yyyy-MM-dd}.log.gz'.
11:28:33,231 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - Roll-over at midnight.
11:28:33,234 |-INFO in c.q.l.core.rolling.DefaultTimeBasedFileNamingAndTriggeringPolicy - Setting initial period to Wed Nov 22 11:28:33 UTC 2017
11:28:33,235 |-INFO in ch.qos.logback.core.joran.action.NestedComplexPropertyIA - Assuming default type [ch.qos.logback.classic.encoder.PatternLayoutEncoder] for [encoder] property
11:28:33,236 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - Active log file name: log/car-insurance-aggregator.log
11:28:33,236 |-INFO in ch.qos.logback.core.rolling.RollingFileAppender[FILE] - File property is set to [log/car-insurance-aggregator.log]
11:28:33,238 |-INFO in ch.qos.logback.classic.joran.action.LoggerAction - Setting level of logger [business_events] to INFO
11:28:33,238 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [FILE] to Logger[business_events]
11:28:33,238 |-INFO in ch.qos.logback.classic.joran.action.RootLoggerAction - Setting level of ROOT logger to INFO
11:28:33,238 |-INFO in ch.qos.logback.core.joran.action.AppenderRefAction - Attaching appender named [STDOUT] to Logger[ROOT]
11:28:33,238 |-INFO in ch.qos.logback.classic.joran.action.ConfigurationAction - End of configuration.
11:28:33,239 |-INFO in ch.qos.logback.classic.joran.JoranConfigurator@6ea1bcdc - Registering current configuration as safe fallback point
SLF4J: Actual binding is of type [ch.qos.logback.classic.util.ContextSelectorStaticBinder]
2017-11-22 11:28:34,266 [main] INFO  org.eclipse.jetty.util.log - Logging initialized @3093ms

Answer 1

Yeah, this is the beauty and the pain of ruby. I would start with overriding Rails.logger= method in config/application.rb with some (like you say) "announce".

Just add to config/application.rb something like that and watch the logs:

Rails.singleton_class.send('alias_method', :old_logger=, :logger=)
module Rails
  def self.logger=(value)
    puts "Hey logger '#{value.inspect}' starting!"
    self.old_logger = value
  end
end

Or what about just investigating of value of Rails.logger ?

Answer 2

Don't know if it's this you're looking for, but Rails has 5 different log levels ( http://guides.rubyonrails.org/debugging_rails_applications.html ):

2.2 Log Levels

When something is logged, it's printed into the corresponding log if the log level of the message is equal to or higher than the configured log level. If you want to know the current log level, you can call the Rails.logger.level method.

The available log levels are: :debug, :info, :warn, :error, :fatal, and :unknown, corresponding to the log level numbers from 0 up to 5, respectively. To change the default log level, use

config.log_level = :warn