CODEWITHSUNDEEP
rubylogging
scorpion35
scorpion35

Reputation: 1084

Ruby - Set different log levels for different targets

Wondering how to set different log levels for different targets. Below is my Ruby code that writes a line to both Console and File. 

# https://stackoverflow.com/a/6407200
class MultiIO
  def initialize(*targets)
    @targets = targets
  end

  def write(*args)
    @targets.each do |t|
      t.write(*args)
    end
  end

  def close
    @targets.each(&:close)
  end
end

module Logging
  def self.logger(logname, programname, debug = false)
    log_file = File.open(logname, "a")
    log_file.sync = true
    zlogger = Logger.new MultiIO.new(log_file, STDOUT)
    zlogger.level = Logger::INFO
    zlogger.progname = programname
    zlogger.formatter = proc do |serverity, datetime, progname, msg|
      "#{datetime.strftime('%Y-%m-%d %I:%M:%S %p %:::z %Z')} - #{serverity} - [#{progname}] | #{msg}\n"
    end

    zlogger
  end
end

I can set the level to Debug if a special env variable is found, $logger.level = Logger::DEBUG if ENV['enable_debug_logs'] == 'true'

But, not sure how to always write Debug lines to the log file and only Info lines to console.

Does anyone know? Any help is greatly appreciated!

Upvotes: 1

Views: 526

Answers (1)

Tom Lord
Tom Lord

Reputation: 28305

Since the log level is a property of the logger, not of the IO, it sounds to me like what you really need to do is define a MultiLogger rather than a MultiIO. Something along the lines of:

class MultiLogger
  attr_reader :default_level, :default_progname, :default_formatter

  def initialize(**args)
    @default_level = args[:default_level]
    @default_progname = args[:default_progname]
    @default_formatter = args[:default_formatter]
    @loggers = []

    Array(args[:loggers]).each { |logger| add_logger(logger) }
  end

  def add_logger(logger)
    logger.level = default_level if default_level
    logger.progname = default_progname if default_progname
    logger.formatter = default_formatter if default_formatter
    @loggers << logger
  end

  def close
    @loggers.map(&:close)
  end

  Logger::Severity.constants.each do |level|
    define_method(level.downcase) do |*args|                
      @loggers.each { |logger| logger.send(__method__, args) }
    end

    # These methods are a bit weird in the context of a "multi-logger" with varying levels,
    # since they are now returning an `Array`; never a falsey value.
    # You may want to define them differently, e.g. `@loggers.all? {...}`, or use a non-predicate method name here.
    define_method("#{level.downcase}?".to_sym) do
      @loggers.map(&__method__)
    end
  end
end

# Usage:

log_file = File.open(logname, "a")
log_file.sync = true 
file_logger = Logger.new(log_file)

console_logger = Logger.new(STDOUT)
console_logger.level = Logger::INFO

multi_logger = MultiLogger.new(
  default_progname: programname,
  default_formatter: proc do |severity, datetime, progname, msg|
      "#{datetime.strftime('%Y-%m-%d %I:%M:%S %p %:::z %Z')} - #{severity} - [#{progname}] | #{msg}\n"
    end,
  loggers: [file_logger, console_logger]
)

Upvotes: 2

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