Some Notes Regarding Rsyslog and Remote Logging for Rails Apps

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We use SyslogLogger gem in order to forward rails application log to system log.

in rails Gemfile:

group :production do
  gem "SyslogLogger", "~> 2.0", :require => 'syslog/logger'
end

in config/environments/production.rb

config.logger = Syslog::Logger.new "rails_application_name"

The problem was that logs actually were forwarded to syslog, messages and user.log and sent to remote server and written to syslog, messages and user.log there. I was asked to make things DRY(ier).

The issue was caused, of cource, by some nasty *.* patterns in rsyslog config. If you’re experiencing similar issues, check /etc/rsyslog.d directory which contains rsyslog configuration files. Make sure you have separate config file for your application and it has higher load priority, for example:

# ls -l

-rw-r--r-- 1 root root   98 Jan  2 16:36 40-rails_application_name.conf
-rw-r--r-- 1 root root 1605 Dec 10  2010 50-default.conf

rules in 40-rails_application_name.conf will be checked first. Contents of 40-rails_application_name.conf file on rails application server:

if $programname == 'rails_application_name' then @@your.logging.server.ip.com:61514
& ~

Note “& ~”, it means log entry will be sent using TCP to your.logging.server.ip.com:61514 and won’t be processed further. This was missing and entries were forwarded to local log files. If you do need to log to the local file, don’t add “& ~”.

rules in 40-rails_application_name.conf file on log server:

$ModLoad imtcp
$InputTCPServerRun 61514

if $programname == 'rails_application_name' then /var/log/rails_application_name.log
& ~

Now logs are stored correctly.

Here is a complete guide for those who needs more details regarding rsyslog configuration.