Using paramiko to tunnel an MySql port when django starts - django

Question

I am trying to connect to a remote MySql server from my local machine.
I want to run it whenever the DEBUG constant is set to true.
Here's the script:
import select
import SocketServer
import sys
import threading
import paramiko
SSH_PORT = 22
DEFAULT_PORT = 4000
g_verbose = True
class ForwardServer (SocketServer.ThreadingTCPServer):
daemon_threads = True
allow_reuse_address = True
class Handler (SocketServer.BaseRequestHandler):
def handle(self):
try:
chan = self.ssh_transport.open_channel('direct-tcpip',
(self.chain_host, self.chain_port),
self.request.getpeername())
except Exception, e:
verbose('Incoming request to %s:%d failed: %s' % (self.chain_host,
self.chain_port,
repr(e)))
return
if chan is None:
verbose('Incoming request to %s:%d was rejected by the SSH server.' %
(self.chain_host, self.chain_port))
return
verbose('Connected! Tunnel open %r -> %r -> %r' % (self.request.getpeername(),
chan.getpeername(), (self.chain_host, self.chain_port)))
while True:
r, w, x = select.select([self.request, chan], [], [])
if self.request in r:
data = self.request.recv(1024)
if len(data) == 0:
break
chan.send(data)
if chan in r:
data = chan.recv(1024)
if len(data) == 0:
break
self.request.send(data)
chan.close()
self.request.close()
verbose('Tunnel closed from %r' % (self.request.getpeername(),))
def forward_tunnel(local_port, remote_host, remote_port, transport):
# this is a little convoluted, but lets me configure things for the Handler
# object. (SocketServer doesn't give Handlers any way to access the outer
# server normally.)
class SubHander (Handler):
chain_host = remote_host
chain_port = remote_port
ssh_transport = transport
ForwardServer(('', local_port), SubHander).serve_forever()
def verbose(s):
if g_verbose:
print s
HELP = """\
Set up a forward tunnel across an SSH server, using paramiko. A local port
(given with -p) is forwarded across an SSH session to an address:port from
the SSH server. This is similar to the openssh -L option.
"""
def forward():
client = paramiko.SSHClient()
client.load_system_host_keys()
client.set_missing_host_key_policy(paramiko.WarningPolicy())
try:
print 'connecting'
client.connect('*******', username='***', password='****!')
print 'connected'
except Exception, e:
print '*** Failed to connect to %s:%d: %r' % ('*****', 22, e)
sys.exit(1)
try:
forward_tunnel(3306, '127.0.0.1', 3306, client.get_transport())
except SystemExit:
print 'C-c: Port forwarding stopped.'
sys.exit(0)
I have two problems here:
1) I don't know how and when to call my forward function when django raises.
2) When I access django locally and run the script from the console I get the following exception:
exception happened during
processing of request from
('127.0.0.1', 41872) Traceback (most
recent call last): File
"/usr/lib/python2.6/SocketServer.py",
line 558, in process_request_thread
self.finish_request(request, client_address) File
"/usr/lib/python2.6/SocketServer.py",
line 320, in finish_request
self.RequestHandlerClass(request, client_address, self) File
"/usr/lib/python2.6/SocketServer.py",
line 615, in init
self.handle() File "/home/omer/Aptana Studio 3
Workspace/Website/src/ssh_tunnel/tunnel.py",
line 51, in handle
verbose('Tunnel closed from %r' % (self.request.getpeername(),)) File
"", line 1, in getpeername
File "/usr/lib/python2.6/socket.py",
line 165, in _dummy
raise error(EBADF, 'Bad file descriptor') error: [Errno 9] Bad file
descriptor
Was this a bad idea to begin with?
Should I do this manually every time?

Answer 1

I don't think it's a bad idea.
I don't think you need to do it manually.
The exception is a bug in paramiko's forward code sample. This has been addressed by jhalcrow in the pull request here:
https://github.com/paramiko/paramiko/pull/36
This post has some code to do it in a more event driven way, i.e if you wanted to call it via some web event hooks in your django code or the like:
Paramiko SSH Tunnel Shutdown Issue

Answer 2

humm, i didn't try this, but if you are on linux, could you run
ssh -L 3306:localhost:3306 remote.host.ip
through python system call when DEBUG is set?
also if you are on Windows, try putty with port forwarding