ws-repl

Arbitrary REPL in a web-page using websocketd.

Quick Start

• Get websocketd
• Copy the ws-repl.html file into a browsable location
• Edit your web-server config to expose the websocket (use the provided nginx-config fragment as a guide)
• Run the backend process in websocketd (see the examples.sh file for inspiration)
• Browse to the page

Widget detail

The javascript can be used as a widget on arbitrary web-pages. Just place <div id="repl"></div> wherever you want it to appear. It can be customised extensively (including changing the div's id from "repl") by passing parameters to the init function, for example:

wsrepl({socketProto: 'wss', bufferLines=300, replBorderStyle: 'dashed'});

See defArgs in ws-repl.js to see what can be customised.

Notes

• This just pipes STDIN/STDOUT from/to the browser, so any highly interactive process which uses terminal control-codes (e.g. ncurses) will of course not work.
• This presumes a relatively recent browser with the usual HTML5 capabilities, code has not been bloated to accomodate old browsers - that can easily be done with backwards-compat javascript shims.
• In the interests of simplicity this includes no security provisions, so if you use it in a public-facing web-page BE SURE to sandbox it if it does anything invasive or non-trivial, and/or include some form of password/token protection if you intend it for trusted users.
• Even then, if running anything more complex than a basic echo-server still think hard how much you trust your logged-in users to mess around with it.
• Lastly, don't run the backend websocketd as root. That would be profoundly silly.

Backend invocation examples

• picolisp REPL:

  websocketd --address=127.0.0.1 --port=8080 pil
  

• picolisp REPL (with sed to trim ': '):

  websocketd --address=127.0.0.1 --port=8080 sh -c 'pil | sed -u -e "s/^: //"'
  

• ruby REPL:

  websocketd --address=127.0.0.1 --port=8080 irb
  

• simple echo server:

  websocketd --address=127.0.0.1 --port=8080 sh -c 'while IFS= read -r input; do printf "You said: %s\\n" "${input}"; done'
  

• poor man's SSH if run over https with http-auth? (just kidding)

  websocketd --address=127.0.0.1 --port=8080 sh -c 'sh 2>&1'
  

Screenshots

Code

This can be found on github. Report bugs either through the issue-tracker there or by email to rowan at rowanthorpe dot com.