Ruby Logger
Well like most languages Ruby has an inbuilt logger Class to do just that. log, and in my case this comes in handy for logging the trail of destruction my Ruby code imparts in the irb compiler.
One thing to note is that you will need to add
require "logger"
At the start of all of your scripts, but let’s get going, fire up irb in your terminal and paste in below:
require "logger"
logger = Logger.new(STDOUT)
logger.debug("I'm a debug log")
and you will get below back
D, [2021-11-23T20:41:26.551530 #127047] DEBUG -- : I'm a debug log
That’s grand 🔥 as you can see we have a time-stamp, the log type in this case DEBUG and the message.
Attributes we can also change out of the box
logger.level
logger.level = Logger::WARN
There are 6 levels of logging heaven which you can set your log to :
Logger::DEBUG, Logger::INFO, Logger::WARN, Logger::Error, Logger::FATAL, and Logger::UNKOWN
Important note, once you set a level of log, the logger will NOT record logs at a ‘lower’ alert level
logger.datetime_format
logger.datetime_format = "%Y-%m-%d %H:%M"
Using your favourite strftime site you can setup your time stamp to read just have you like.
logger.progname
logger.progname = 'home-of-log'
Set the progname of the log to help you find that needle in the haystack, and label just where the log came from in your programing misadventure.
Let’s put all that together using .tap which I stumbled onto today.
logger.tap do |attribute|
attribute.level = Logger::DEBUG
attribute.datetime_format = '%d %m %Y %H:%M:%S'
attribute.progname = 'log-of-the-day'
end
format ahoy
Every log needs a custom format surely, you can use a proc to setup a formatter for your logs.
logger.formatter = proc do |severity, datetime, progname, msg|
date_format = datetime.strftime('%Y-%m-%d %H:%M:%S')
"#{progname} date=[#{date_format}] severity=#{severity.ljust(5)} pid=##{Process.pid} message='#{msg}'\n"
end
save me..
In order to save your logs into an actual file you need to pass those requirements onto the Logger.new instance like below
logger = Logger.new('i_like_to_log_it.log')
or pass in custom args to slice up, or remove your log after an amount of time, or size.
# Keep data for the current week.
Logger.new('my_weekly_logs.log', 'weekly')
# Keep data for today and the past 2 months.
Logger.new('my_latest_2_months_logs.log', 2, 'monthly')
# Restarts the log over when it exceeds 26GB in size.
Logger.new('my_custom_logs.log', 0, 20 * 1024 * 1024 * 1024)
here’s one I’ve prepared earlier
Ok, it’s that time of the blog post where you put the code block into your iterm and everything ( hopefully ).. works.
End result should be a lovely formated log just like below 😁 🥵
# Logfile created on 2021-11-23 21:59:40 +1100 by logger.rb/v1.4.3
ITS-HERE--> date=[2021-11-23 21:59:40] severity=DEBUG pid=145879 message='I'm a debug log'
ITS-HERE--> date=[2021-11-23 21:59:40] severity=INFO pid=145879 message='I'm an info log'
ITS-HERE--> date=[2021-11-23 21:59:40] severity=WARN pid=145879 message='I'm a warn log'
ITS-HERE--> date=[2021-11-23 21:59:40] severity=ERROR pid=145879 message='I'm an error log: error message'
ITS-HERE--> date=[2021-11-23 21:59:42] severity=FATAL pid=145879 message='I'm a fatal log'
Copy below and then check in your code editor for the 'i_like_to_log_it.log' log file.
require "logger"
logger = Logger.new('i_like_to_log_it.log')
logger.tap do |attribute|
attribute.level = Logger::DEBUG
attribute.datetime_format = '%d %m %Y %H:%M:%S'
attribute.progname = 'ITS-HERE-->'
end
logger.formatter = proc do |severity, datetime, progname, msg|
date_format = datetime.strftime('%Y-%m-%d %H:%M:%S')
"#{progname} date=[#{date_format}] severity=#{severity.ljust(5)} pid=#{Process.pid} message='#{msg}'\n"
end
### here comes the logs..
logger.debug("I'm a debug log")
logger.info("I'm an info log")
logger.warn("I'm a warn log")
logger.error("I'm an error log: error message")
logger.fatal("I'm a fatal log")
that’s a log for now..
Thank you sticking around to check out logs and I’ll see you at next weeks topic.