Ruby - Set different log levels for different targets - ruby

Question

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!

Answer 1

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]
)