Connecting to a remote IPython instance

Question

I would like to run an IPython instance on one machine and connect to it (over LAN) from a different process (to run some python commands). I understand that it is possible with zmq : http://ipython.org/ipython-doc/dev/development/ipythonzmq.html .

However, I can not find documentation on how to do it and whether it is even possible yet.

Any help would be appreciated!

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EDIT

I would like to be able to connect to IPython kernel instance and send it python commands. However, this should not be done via a graphic tool (qtconsole) , but I want to be able to connect to that kernel instance from within a different python script...

e.g.

external.py

somehow_connect_to_ipython_kernel_instance instance.run_command("a=6") 

Answer 1

If you want to run code in a kernel from another Python program, the easiest way is to connect a BlockingKernelManager. The best example of this right now is Paul Ivanov's vim-ipython client, or IPython's own terminal client.

The gist:

• ipython kernels write JSON connection files, in IPYTHONDIR/profile_<name>/security/kernel-<id>.json, which contain information necessary for various clients to connect and execute code.
• KernelManagers are the objects that are used to communicate with kernels (execute code, receive results, etc.). *

A working example:

In a shell, do ipython kernel (or ipython qtconsole, if you want to share a kernel with an already running GUI):

$> ipython kernel [IPKernelApp] To connect another client to this kernel, use: [IPKernelApp] --existing kernel-6759.json 

This wrote the 'kernel-6759.json' file

Then you can run this Python snippet to connect a KernelManager, and run some code:

from IPython.lib.kernel import find_connection_file from IPython.zmq.blockingkernelmanager import BlockingKernelManager  # this is a helper method for turning a fraction of a connection-file name # into a full path.  If you already know the full path, you can just use that cf = find_connection_file('6759')  km = BlockingKernelManager(connection_file=cf) # load connection info and init communication km.load_connection_file() km.start_channels()  def run_cell(km, code):     # now we can run code.  This is done on the shell channel     shell = km.shell_channel     print     print "running:"     print code      # execution is immediate and async, returning a UUID     msg_id = shell.execute(code)     # get_msg can block for a reply     reply = shell.get_msg()      status = reply['content']['status']     if status == 'ok':         print 'succeeded!'     elif status == 'error':         print 'failed!'         for line in reply['content']['traceback']:             print line  run_cell(km, 'a=5') run_cell(km, 'b=0') run_cell(km, 'c=a/b') 

The output of a run:

running: a=5 succeeded!  running: b=0 succeeded!  running: c=a/b failed! --------------------------------------------------------------------------- ZeroDivisionError                         Traceback (most recent call last) /Users/minrk/<ipython-input-11-fb3f79bd285b> in <module>() ----> 1 c=a/b  ZeroDivisionError: integer division or modulo by zero 

see the message spec for more information on how to interpret the reply. If relevant, stdout/err and display data will come over km.iopub_channel, and you can use the msg_id returned by shell.execute() to associate output with a given execution.

PS: I apologize for the quality of the documentation of these new features. We have a lot of writing to do.