This document discusses using Ruby on embedded devices. It notes that while Ruby has good network libraries and is platform independent, using gems can be problematic due to dependencies. It recommends using alternative languages for specific tasks, like C for performance critical code, Bash for portable scripts, Flex for pattern matching, and Go for networking. It also recommends using jit to compile scripts to native binaries for performance. The document promotes UN*X tools over rebuilding functionality in Ruby and ends by mentioning they are crowdfunding their project at https://getkinko.com.

1. Ruby on Embedded
Devices

3. What is kinko.me
4 PGP-based email encryption
4 for your desktop and your mobiles
4 with your current email address
Also
4 comes on a dedicated device

4. ssshhh...
as of this afternoon we are crowdfunding.
Feel invited to check https://getkinko.com

5. Hardware
4 A10 1GHz Cortex-A8 ARMv7 CPU, VFPv3,
NEON, Mali 400 GPU, CedarX VPU
4 512MB DDR3 RAM memory
4 SD storage

6. Compared to modern machines
4 CPU: 10x
4 IO throughput: ~50x
(RAM is ok, though)

7. Is this good enough?
4 Compared to Intel 386: yes
4 Compared with servers: a different usage
patterns
4 low traffic volume
4 few requests to HTTPS frontend

8. Herding cats

9. Existing projects
4 nginx/dovecot: HTTP + IMAP servers (C)
4 GnuPG: PGP encryption (C)
4 imapsync: IMAP synchronization
(Python)
4 bonjour, monit (C)
4 OpenSSH: tunnelling (C/ruby)
4 roundcube webmail: Webmail (PHP)

10. + not so secret sauce
4 imapsync patch (Python)
4 configuration frontend (Ruby)
4 smtp server + client (Go)
4 installer (Ruby+Shell)
4 gluing code: (Ruby, Shell, C, Flex)

11. Why Ruby?

12. 4 greatest language in the world
4 good network libraries
4 platform independent, kind of
4 Sinatra rocks

13. Why not Ruby?

14. gems + bundler
gems, bundler and all that mess
4 gems are platform independent. Well,
mostly.
4 bundler: hard to manage over accounts

15. Performance
4 once started performance is ok:
4 ~10 to 20 pages rendered per second
4 startup performance is really bad:
4 starting a sinatra/ActiveRecord app:
~15 seconds

16. Performance Ruby vs C
# ~30 msecs
date
# ~150 msecs
ruby -e 'puts Time.now'

17. Lessons learned
4 Configuration UI in ruby/sinatra (for
now)
4 everything else: mostly not.

18. Tipps & Tricks

19. 1. UN*X is your friend

20. UN*X is your friend
4 caching: file system cache
4 resources: cleans up after you
4 shared storage: file system
4 built-in authentication: users + groups
4 also: ulimit, chroot, etc.

21. ... Don't rebuild it in ruby
A custom logger in ruby:
logger = Logger.new("#{Rails.root}/log/custom.log", 'daily')
logger.formatter = proc do |severity, time, _, msg|
"#{time.strftime("%B %d %H:%M:%S")} #{severity} #{msg}n"
end
config.logger = logger

22. ... Don't rebuild it in ruby, pt. 2
A custom logger in external application:
reader, writer = IO.pipe
fork do
Process.setpgrp
STDIN.reopen reader
writer.close
exec("timestamp")
end
STDOUT.reopen writer
STDERR.reopen writer
reader.close

23. ... Don't rebuild it in ruby, pt. 3
or simply:
rackup 2>&1 | timestamp

24. ... Don't rebuild it
ditto:
4 daemons
4 process management
4 etc.
(Hello devops!)

25. 2. Alternative Languages

26. fast and "portable": bash
#!/bin/bash
set -eu
set -o pipefail
echo "Yay!"
Commands are (sometimes) not portable:
echo -n "Is there a newline?"

27. small & fast: C
POSIX at your fingertips.
4 fast
4 small
4 source: somewhat portable; '#ifdef
linux' FTW!

28. Pattern matching: flex
Pattern matching done quickly; in portable
source code.
/* Replaces ${{NAME}} from the environment */
${{[a-zA-Z0-9_]+}} {
yytext[yyleng-2] = 0;
const char* env = yytext+3;
const char* value = getenv(env);
printf("%s", value ? value : "");
}

29. networking: Go
Go, the environment
4 fast, portable source
4 good networking + email libraries (even
SSH!)
4 crosscompiling: easy
Go, the language
4 terrible.

30. jit: Distribute scripted binaries
Use jit!
http://github.com/radiospiel/jit
4 Works with C, flex, Go
4 Compiles just in or ahead of time
4 Native speed
(Built in bash, BTW)

31. jit: C Example
Source:
#!/usr/bin/env jit.cc
#include <stdio.h>
void main() {
printf("Hello world!n");
}
Run:
chmod +755 hello
./hello

32. Links
4 flex: http://flex.sourceforge.net/
4 jit: http://github.com/radiospiel/jit

33. We are crowdfunding.
https://getkinko.com