Exposing services on csclub.uwaterloo.ca

I will admit I didn't get very much out of the University of Waterloo other than layers of geese shit caked under my shoes, but the computer science club is a gem.

If you're a current student or alumni, I highly recommend paying for the termly membership -- at the time of writing, it's 2 dollars a term. I've given them a decent chunk of cash at some point so I won't have to keep thinking about renewing.

The CSC generously gives you some web space. It should be accessible at csclub.uwaterloo.ca/~WATIAM, but don't go to mine because I've very sinfully hardcoded my domain name so things will be broken.

Throwing html in your ~/www folder will be immediately accessible at the above URL, but what if you want to run a server?

First, choose a high port number nobody's using. Say, 33333.

Then, log into caffeine.csclub.uwaterloo.ca, the webserver. In your ~/www folder, make a file called .htaccess and add the following:

Options +FollowSymLinks                                                      
RewriteEngine On

RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f
RewriteRule "^test/(.*)$" "http://localhost:33333/$1" [P]

I don't know much about Apache's .htaccess configuration language, but you can think of "^test/(.*)$" like a regex that looks for urls of the form csclub.uwaterloo.ca/~WATIAM/test/------- and maps them to http://localhost:33333/$1 where $1 is all the stuff that comes after ~WATIAM/test/

We're in caffeine, the server that's processing the requests, so let's run a simple python server to test this out. Run

/usr/bin/python3 -m http.server 33333

(or instead of 33333, whatever high port number you've chosen)

This creates a small server running at localhost:33333 that displays all the stuff in the directory you ran the program from.

Now, head to http://csclub.uwaterloo.ca/~WATIAM/test/ (trailing slash!!) and voila! A real live program exposed to the internet! You should probably shut it down before someone mucks through all your files.

At the time of writing, this is how my parking ticket visualizer dynamically responds to requests.

There's a bit more involved if you want to keep your service running, and for longer. I won't pretend to have it all figured it out, but for starters

• Use a real web server! One that can handle lots of requests (e.g., not your built-in Flask/Django development server). For python, try gunicorn.
• If your service is heavy, offload it to one of the CSC's other servers. I currently use an SSH reverse proxy to have caffeine see my service (on hfcs) as if it's on localhost. I really think there has to be a better way, but.. I don't know how! Please, if you have any ideas, I'm all ears! Shoot me an email!

Exercises!

• Host your own blog on the csclub!
• Can you expose a jupyter notebook instance?
• How would you proxy services to caffeine?

This is mostly parroted from the CSC's wiki page, I suggest you also read that.

Happy hosting!