Ruby on embedded devices rug::b Aug 2014

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

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

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

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

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

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)

+ 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)

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

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

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

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

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

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.

... 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

... 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

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

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

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

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

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 : "");
}

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

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)

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

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

We are crowdfunding.
https://getkinko.com

Ruby on embedded devices rug::b Aug 2014

Ruby on embedded devices rug::b Aug 2014

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