puts vs logger in rails rake tasks

In a rake task if I use puts command then I see the output on console. However I will not see that message in log file when app is deployed on production.

However if I say Rails.logger.info then in development mode I see nothing on console. I need to go to log file and tail that.

I would ideally like to use Rails.logger.info and in development mode inside the rake task, the output from logger should also be sent to console.

Is there a way to achieve that?

Put this in application.rb, or in a rake task initialize code

if defined?(Rails) && (Rails.env == 'development')
  Rails.logger = Logger.new(STDOUT)
end

This is Rails 3 code. Note that this will override logging to development.log. If you want both STDOUT and development.log you'll need a wrapper function.

If you'd like this behaviour only in the Rails console, place the same block of code in your ~/.irbrc.

You could create a new rake task to get this to work.

desc "switch logger to stdout"
task :to_stdout => [:environment] do
 Rails.logger = Logger.new(STDOUT)
end

This way when you execute your rake task you can add to_stdout first to get stdout log messages or don't include it to have messages sent to the default log file

rake to_stdout some_task

Rake tasks are run by a user, on a command-line. Anything they need to know right away ("processed 5 rows") should be output on the terminal with puts.

Anything that needs to be kept for posterity ("sent warning email to [email protected]") should be sent to the Rails.logger.

Code

For Rails 4 and newer, you can use Logger broadcast.

If you want to get both STDOUT and file logging for rake tasks in development mode, you can add this code into config/environments/development.rb :

  if File.basename($0) == 'rake'
    # http://stackoverflow.com/questions/2246141/puts-vs-logger-in-rails-rake-tasks
    log_file     = Rails.root.join("log", "#{Rails.env}.log")
    Rails.logger = ActiveSupport::Logger.new(log_file)
    Rails.logger.extend(ActiveSupport::Logger.broadcast(ActiveSupport::Logger.new(STDOUT)))
  end

Test

Here's a small Rake task to test the above code :

# lib/tasks/stdout_and_log.rake
namespace :stdout_and_log do
  desc "Test if Rails.logger outputs to STDOUT and log file"
  task :test => :environment do
    puts "HELLO FROM PUTS"
    Rails.logger.info "HELLO FROM LOGGER"
  end
end

Running rake stdout_and_log:test outputs

HELLO FROM PUTS
HELLO FROM LOGGER

while

HELLO FROM LOGGER

has been added to log/development.log.

Running rake stdout_and_log:test RAILS_ENV=production outputs

HELLO FROM PUTS

while

HELLO FROM LOGGER

has been added to log/production.log.

I'd say that using Rails.logger.info is the way to go.

You won't be able to see it in the server console because it won't run via the server. Just open up a new console and tail -f the log file, it'll do the trick.

> Many users are aware of the UNIX® > command 'tail', which can be used to > display the last few lines of a large > file. This can be useful for viewing > log files, etc. > > Even more useful in some situations, > is the '-f' parameter to the 'tail' > command. This causes tail to 'follow' > the output of the file. Initially, the > response will be the same as for > 'tail' on its own - the last few lines > of the file will be displayed. > However, the command does not return > to the prompt, and instead, continues > to 'follow' the file. When additional > lines are added to the file, they will > be displayed on the terminal. This is > very useful for watching log files, or > any other file which may be appended > over time. Type 'man tail' for more > details on this and other tail > options.

(via)

Execute a background job with '&' and open script/console or whatever.. That way you can run multiple commands in the same window.

tail -f log/development.log &
script/console
Loading development environment (Rails 2.3.5)
>> Product.all
2011-03-10 11:56:00 18062 DEBUG  Product Load (6.0ms)  SELECT * FROM "products"
[<Product.1>,<Product.2>]

note Can get sloppy quickly when there is a lot of logging output.

In Rails 2.X to redirect the logger to STDOUT in models:

ActiveRecord::Base.logger = Logger.new(STDOUT)

To redirect logger in controllers:

ActionController::Base.logger = Logger.new(STDOUT)

How about creating an application helper which detects which environment is running and does the right thing?

def output_debug(info)
   if RAILS_ENV == "development"
      puts info
   else
      logger.info info
   end
end

Then call output_debug instead of puts or logger.info