Ruby on embedded devices rug::b Aug 2014

Ruby on Embedded Devices

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

Herding cats

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)

Why Ruby?

4 greatest language in the world

4 good network libraries

4 platform independent, kind of

4 Sinatra rocks

Why not Ruby?

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 msecsdate

# ~150 msecsruby -e 'puts Time.now'

Lessons learned4 Configuration UI in ruby/sinatra (for

now)

4 everything else: mostly not.

Tipps & Tricks

1. UN*X is your friend

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!)

2. Alternative Languages

fast and "portable": bash

#!/bin/bashset -euset -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