daeltar's

Capistrano task to generate Logrotate config

Motivation: your logs are growing request by request and your free disk space is smaller and smaller. Solution is log rotation with logrotate.

Requirements:

• nginx + passenger (installed in /opt/nginx)
• logrotate (aptitude install logrotate)
• capistrano (deploying into /home/web/YOUR_APPLICATION_NAME)
• logs to rotate (production.log, access.log, error.log, newrelic_agent.log, …)

Capistrano part

Logrotate configuration will be generated from ERB template:

# logrotate.erb.conf
# Logrotate config for <%= application %>
# Generated at <%= Time.now.strftime("%d.%m.%Y, %H:%M") %>
<%= shared_path %>/log/*.log {
  daily
  missingok
  rotate 30
  compress
  delaycompress
  sharedscripts
  olddir <%= shared_path %>/log/old
  postrotate
    test ! -f /opt/nginx/logs/nginx.pid || kill -USR1 `cat /opt/nginx/logs/nginx.pid`
  endscript
}

Notes:

• old logs moved under old directory, compressed and kept for 30 days
• no slow copytruncate, after rotation of all logs in directory (sharedscripts) send USR1 signal to nginx to reopen logs

To generate logrotate configuration use following capistrano task:

# logrotate.rb Capistrano task
namespace :logrotate do
  desc "Create logrotate configuration file"
  task :create_conf, :roles => :web do
    template = File.read(File.join(File.dirname(__FILE__), "logrotate.conf.erb"))
    buffer   = ERB.new(template).result(binding)
    put buffer, "#{shared_path}/config/logrotate.conf"
  end
end
after 'setup', 'logrotate:create_conf'

Server part

To include generated configuration file add following to server’s /etc/logrotate.conf

include /home/web/YOUR_APPLICATION_NAME/shared/config/logrotate.conf

To ensure periodic rotation logrotate relies on daily execution by cron. In Debian it is placed in /etc/cron.daily/logrotate.

Resume

I have seen examples promoting virtual host generation from ERB template by capistrano tasks but why not apply it to generating logrotate configuration? You got it bundled (and versioned) with your application sources and that is big win.