Rubygems - behind the gems.

RUBYGEMS
...behind the gems
Roland Moriz ~ Moriz GmbH
Ruby User Group München 26.10.2010
http://moriz.de/

http://moriz.de/Rubygems behind the gems.
Hello blaaa bla Moriz GmbH bla bla Software Development
Services bla bla bla bla Consulting bla blaaaa bla blaaaaaa
bla Infrastructure Services bla bla Roland bla bla bla bla
professional software development since 1999 bla bla
Amazon Marketplace Deutschland bla bla bla Tiscali
Games bla bla FIFA WM 2006 bla Yahoo.de bla bla bla bla
two billion pageviews bla bla blala Allianz24.de/
Allsecur.de bla bla bla Ruby User Group München bla bla
blabla http://moriz.de/ bla blaaaba http://rails.io bla
http://boot.io blablabla recently hetzner-api gem bla bla
bla and the slides will be available @ http://moriz.de/talks/
rubygems.
;-)

RUBYGEMS MOVING PARTS
rubygems / cli gemcutter
gem
code / library, app, data, meta

RUBYGEMS MOVING PARTS
rubygems / cli gemcutter
$ gem
require ”rubygems“
http://rubygems.org/
(and extensions to the rubygems client)
distribution
creation, download, setup,
usage (index building, server)

RUBYGEMS FACTS
• used by nearly every ruby project
• the core of the ruby ecosystem
• standard lib (with MRI 1.9.x)
• 17.000+ gem projects
• 81.000+ gem files
• 23 GB+

http://moriz.de/
started at RubyConf 2003 by:
• Rich Kilmer
• Chad Fowler
• David Black
• Paul Brannan
• Jim Weirch
> http://rubyforge.org/projects/rubygems/
Rubygems behind the gems.
RUBYGEMS FACTS

GEM FACTS
• described by a .gemspec
• gem build my.gemspec
easier ways:
• bundler, jewler, newgem(?), ...

GEM FACTS
tar xvf rails-3.0.1.gem
x data.tar.gz
x metadata.gz
contents:

GEM FACTS
metadata.gz > gzipped YAML
data.tar.gz > payload

GEMCUTTER FACTS
• started in April 2009
• is now rubygems.org (rubygems 1.3.6+)
• replaced rubyforge
• manages uploads & downloads
• rails app using PostgreSQL +
rack middleware with sinatra
• by Nick Quaranto (@qrush) of Thoughtbot
> http://github.com/rubygems/gemcutter

BIG PICTURE: UPLOAD RELEASE
$ gem release hetzner-api.gemspec
Successfully built RubyGem
Name: hetzner-api
Version: 1.0.0
File: hetzner-api-1.0.0.gem
Pushing gem to RubyGems.org...
gem release

cli
rubygems.org (gemcutter)

cli
rubygems.org
AWS S3
gem file

cli
rubygems.org
AWS S3 update specs
> database
> spec files to s3
spec files

cli
rubygems.org
AWS S3 update specs
webhooks, rss, ...
http://rubygems.org/pages/api_docs

BIG PICTURE: DOWNLOAD
cli
rubygems.org AWS S3

SPECS AKA „THE INDEX“
$sudo gem install rails -V
GET http://gems.rubyforge.org/latest_specs.4.8.gz
302 Found
GET http://production.s3.rubygems.org/latest_specs.4.8.gz
200 OK
GET http://gems.rubyforge.org/quick/Marshal.4.8/rails-3.0.1.gemspec.rz
302 Found
GET http://production.s3.rubygems.org/quick/Marshal.4.8/rails-3.0.1.gemspec.rz
200 OK
GET http://gems.rubyforge.org/specs.4.8.gz
302 Found
GET http://production.s3.rubygems.org/specs.4.8.gz
200 OK
GET http://gems.rubyforge.org/quick/Marshal.4.8/activesupport-3.0.1.gemspec.rz
302 Found
GET http://production.s3.rubygems.org/quick/Marshal.4.8/activesupport-3.0.1.gemspec.rz
...

SPECS AKA „THE INDEX“no specific version
=> latest
302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...

302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...
Gem.marshal_version
=> Marshal::MAJOR_VERSION
Marshal::MINOR_VERSION

irb(main):001:0> x = {}
=> {}
irb(main):002:0> x['farbe'] = 'ananasblau'
=> "ananasblau"
irb(main):003:0> Marshal.dump x
=> "004b{006"nfarbe"017ananasblau"
etc.
> http://ruby-doc.org/core/classes/Marshal.html

302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...

latest_specs:
lists the latest release number of all gems (~150 KB / 570 KB)
specs:
list of all gem releases (380 KB / 2.2 MB)
latest_specs = Marshal.load open 'latest_specs.4.8'
latest_specs.size
=> 17501
specs = Marshal.load open 'specs.4.8'; specs.size
=> 83490
(there‘s also a pre-release spec (remember „gem install rails --pre“) and others: see
rubygems source lib/rubygems/commands/generate_index_command.rb)

302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...
xload + parse spec
dependencies

Gem::Specification.new do |s|
  s.authors = ["David Heinemeier Hansson"]
  s.date = Time.utc(2010, 10, 14)
  s.dependencies = [Gem::Dependency.new("activesupport",
    Gem::Requirement.new(["= 3.0.1"]),
    :runtime),
   Gem::Dependency.new("actionpack",
    :runtime),
   Gem::Dependency.new("activerecord",
    :runtime),
   Gem::Dependency.new("activeresource",
    :runtime),
   Gem::Dependency.new("actionmailer",
    :runtime),
   Gem::Dependency.new("railties",
    :runtime),
   Gem::Dependency.new("bundler",
    Gem::Requirement.new(["~> 1.0.0"]),
    :runtime)]
  s.description = "Ruby on Rails is a full-stack web framework optimized
Marshal.load Gem.inflate File.read 'rails-3.0.1.gemspec.rz'

302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...
deps with explicit
version requirement =>
require full spec list

302 Found
200 OK
302 Found
200 OK
302 Found
200 OK
302 Found
...
for each dependency
then download and install the .gem files

PROBLEMS: WHAT IF?
cli
rubygems.org
AWS S3

PROBLEMS: WHAT IF?
cli
rubygems.org
AWS S3
Temporary Outage:
no new gem releases
no gem downloads (index missing)
!
new app deployments?
new server deployments?

PROBLEMS: WHAT IF?
cli
rubygems.org
AWS S3
Fatal Outage, reasons:
• Hardware
• Software (attack, fs corruption)
• Amazon
• account „deactivation“
• account deletion
• S3 data loss
• S3 bucket account theft/crack
• Sunny day kills all the clouds.
• Jeff Bezos‘ new bicy^Segw^Rocket.

PROBLEMS: WHAT IF?
cli
rubygems.org
AWS S3
Fatal Outage:
ALL GEMS LOST

PROBLEMS: WHAT IF?
cli
rubygems.org
AWS S3
Fatal Outage:
ALL GEMS LOST
try again. ^_^

PROBLEMS: MIRRORING
Infrastructure independence to save your
business from a rubygems desaster:
> Start your own mirror
Fallback for rubygems.org desaster?
> Use a public mirror
> Start your own mirror

PROBLEMS: PUBLIC MIRRORS
Comprehensive Perl Archive Network
2010-10-25 online since 1995-10-26
7770 MB 228 mirrors
8463 authors 18582 modules
228 independent public and free mirrors!

Debian Mirror Sites: 445
http://www.debian.org/mirror/list

„The Python Package Index is a
repository of software for the Python
programming language.
There are currently 11801 packages here“

0 active, public, free mirrors.
lost in migration (rubyforge > gemcutter)

PROBLEMS: MIRRORING
Mirroring stuff in rubygems is currently broken:
• „gem mirror“ misses some gems
& slow downloads: one gem at a time.
• index building is broken (see #362)
• reliability (#362, too)
http://help.rubygems.org/discussions/problems/362-cant-mirror-rubygems-
repo-incorrect-header-check
http://help.rubygems.org/discussions/problems/212-some-gems-and-specs-missing-that-are-in-the-index
Gemcutter already lost gems:

PROBLEMS: MIRRORING
There is also no easy way to mirror a S3 bucket:
• no ftp
• no rsync
• no file-list to use with e.g. wget
= you cannot even run a reliable private mirror :-(

SOLUTION
Provide rsync on master for sync-ability.
On EC2, Rackspace, does not matter if it‘s fast...
> NO custom mirroring software!
> most FOSS mirror sites use rsync
> use rsync, ask mirrors, problem solved.
> AWS cloudfront is NOT a solution
> not mirrorable, same vendor SPOFs.

SOLUTION
Provide rsync on master for sync-ability.
On EC2, Rackspace, does not matter if it‘s fast...
Provide a DNS based distribution (GeoDNS)
> a realiable base for (private) mirroring
> speed & latency improvements
> NO custom mirroring software needed!
> saves money (AWS and Rackspace fees)
> make use of the new mirrors!

SOLUTION
Why not?
> no „instant deploy“ (real-time mirroring)
> no download stats

SOLUTION
Why not?
Rubygems CLI could fallback to the rubygems.org
master if a gem version is not on the used mirror.
It already does if you configure it.
(current downside: d/l spec-lists from master everytime, looks fixable to me)
> no „instant deploy“ (real-time mirroring)
> no download stats

THINGS WILL FAIL...
just make sure you‘ve a working plan B
AND:
KISS & YAGNI. Keep it simple.
less moving parts > less things that will break.
Don‘t over-engineer.

HELP
OpenSource projects need your support.
Gemcutter/Rubygems, too.
Go contribute if you care about your ruby business.
The Gemcutter source is really awesome,
a good read for every developer.

Rubygems - behind the gems.

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