How to create a ssh tunnel in ruby and then connect to mysql server on the remote host

Question

I would like to create a ruby script that I can run mysql commands on a remote server through a ssh tunnel.

Right now I have a manual process to do this:

1. Create a tunnel -> ssh -L 3307:127.0.0.1:3306
2. run ruby script.
3. Close tunnel.

I would love to be able to automate this so I can just run the script.

example:

require 'rubygems'   
require 'net/ssh/gateway'  
require 'mysql'  


#make the ssh connection -> I don't think I am doing this right.

Net::SSH.start('server','user') do |session|

  session.forward.local(3307,'127.0.0.1', 3306)<br>
  mysql = Mysql.connect("127.0.0.1","root","","",3307)

  dbs = mysql.list_dbs<br>
  dbs.each do |db|<br>
    puts db <br>
  end

  session.loop(0){true}<br>
end

An update - 2010-11-10:
I'm really close with this code:

require 'rubygems'  
require 'mysql'  
require 'net/ssh/gateway'  

gateway = Net::SSH::Gateway.new("host","user",{:verbose => :debug})
port = gateway.open("127.0.0.1",3306,3307)

#  mysql = Mysql.connect("127.0.0.1","user","password","mysql",3307)  
#  puts "here"  
#  mysql.close  

sleep(10)  
gateway.close(port)

When its sleeping, I am able to open a terminal window and connect to mysql on the remote host. This verifies the tunnel is created and working.

The problem now is when I uncomment the 3 lines, it just hangs.

Answer 1

I was able to get this to work without a fork using the mysql2 gem

require 'rubygems'
require 'mysql2'
require 'net/ssh/gateway'

gateway = Net::SSH::Gateway.new(
  'remotehost.com',
  'username'
 )
port = gateway.open('127.0.0.1', 3306, 3307)

client = Mysql2::Client.new(
  host: "127.0.0.1",
  username: 'dbuser',
  password: 'dbpass',
  database: 'dbname',
  port: port
)
results = client.query("SELECT * FROM projects")
results.each do |row|
  p row
end
client.close

Answer 2

This might be one possible solution:

require 'rubygems'  
require 'mysql'  
require 'net/ssh/gateway'  


gateway = Net::SSH::Gateway.new("server","user")  
port = gateway.open("127.0.0.1",3306,3307)

  child = fork do  
    mysql = Mysql.connect("127.0.0.1","user","password","mysql",port)  
    sql = "select sleep(5)"  
    mysql.query(sql)  
    mysql.close  
    exit  
  end  
  puts "child: #{child}"  
Process.wait  
gateway.close(port)  

Maybe there is a better way, but this works for what I was trying to do.