run tail on remote servers with ease

rt.rb

#!/usr/bin/env ruby
require 'rubygems'
require 'yaml'
require 'erb'

ConfigFilePath = File.expand_path("~/.remote-tail.yml")

SampleConfig=<<EOS
---
defaults: &defaults
  host: c3
foonginx:
  file: /var/log/nginx/*.log
barapp:
  host: foo@bar.com
  file: /var/www/apps/railsfooapp/shared/log/*.log
EOS

Usage=<<EOS
Usage:
  1. cd to into the directory whose name is the same as the name of the config and run
     rt

  2. rt <name of the app>

  3. rt <host> <file>
EOS

def tail(opts)
  cmd = "ssh #{opts['host']} 'tail -f #{opts['file']}'"
  puts "running: '#{cmd}'"
  system(cmd)
end

def config(app)
  puts "using app:#{app}"
  config = YAML::load_file ConfigFilePath
  return config[app] if config[app]
  puts "app:#{app} not found in #{ConfigFilePath}"
  puts Usage
  exit 2
end

def setup
  return if File.exist? ConfigFilePath
  puts "creating a sample config at: #{ConfigFilePath}"
  File.open(ConfigFilePath, 'w') do |f|
    f.print SampleConfig
  end
end

def init
  setup
  case ARGV.length
  when 0
    #usage:
    #cd to the app root directory, usually this would be the name with which you
    #setup the configuration and run
    #$ rt
    tail config(File.basename(Dir.pwd))
  when 1
    #usage:
    #from any directory
    #$ rt <name of the app>
    tail config(ARGV.first)
  when 2
    #usage:
    #from any directory
    #$ rt <host> <file>
    tail :host => ARGV.first, :file => ARGV.last
  else
    puts "Invalid number of arguments"
    puts Usage
    exit 1
  end
end

init