SLIME and SWANK are incredible. Start a SWANK server in your application and Whammo! You've can connect to it from the comfort of Emacs. From there you can tinker with its insides to your heart's content. This is a beta-testing dream!
Except when it isn't. Recently I deployed a Common Lisp web application where I ran into some trouble.
Trouble The First: Connection Error
So say that my service is running on
server.com and SWANK is listening on port
4040. Then to connect to it I have been using ssh port forwarding:
ssh -L 4040:localhost:4040 firstname.lastname@example.org
So that I can then do
4040 as its arguments.
You might be surprised, however if you were to have used the following ssh command, which lists the local host ip of
127.0.0.1, instead of
ssh -L 4040:127.0.0.1:4040 email@example.com
For whatever reason, this fails: ssh reports a connection error. So, I had to use
Trouble The Second: SWANK-REQUIRE
The second, and more irksome issue comes up when I actually succeed at connecting via
slime-connect: I immediately drop into the slime debugger. The issue seems to be that
SWANK is trying to load some code upon connection. Obviously, it is not going to be able to load code unless that code is present and available on the server.
In order to get the required code into the deployed binary, I do the following prior to executing
(swank:swank-require '(SWANK-IO-PACKAGE::SWANK-INDENTATION SWANK-IO-PACKAGE::SWANK-TRACE-DIALOG SWANK-IO-PACKAGE::SWANK-PACKAGE-FU SWANK-IO-PACKAGE::SWANK-PRESENTATIONS SWANK-IO-PACKAGE::SWANK-MACROSTEP SWANK-IO-PACKAGE::SWANK-FUZZY SWANK-IO-PACKAGE::SWANK-FANCY-INSPECTOR SWANK-IO-PACKAGE::SWANK-C-P-C SWANK-IO-PACKAGE::SWANK-ARGLISTS SWANK-IO-PACKAGE::SWANK-REPL))
I got the list of required modules directly from the
SLIME debugger. I recompiled, redeployed, and ta-dah! It works!