12 Factor App: Red Dot Ruby Conf

May 18th 2012 Richard Schneeman @schneems the 12factor App Monday,

May 21, 12

Hello Monday, May 21, 12

㟬޷ Monday, May 21, 12

It’s Friday Monday, May 21, 12

whoami • @Schneems • BSME with Honors from Georgia Tech

• 5 + years experience Ruby & Rails • Work for @Heroku • Rails 3.1, 3.2, & 4.0 contributor • 3 + years technical teaching • UT Austin Monday, May 21, 12

Twelve Factor • Can apply to any language • Speeds

up deployment, makes scaling easier & keeps apps clean • Developed over direct exposure to the deployment of hundreds of thousands of apps Monday, May 21, 12

Monday, May 21, 12

Code + Methodology • Speed and confidence through: • Development

environment • Staging environments • Consistent codebase practices • Quick access to logs and metrics • Easy scaling architecture Lets take a look Monday, May 21, 12

Config Monday, May 21, 12

Config • What varies between deploys • resource strings to

databases • credentials to S3, twitter, facebook, etc. • canonical values, hostname • security tokens Monday, May 21, 12

Config Does NOT go in source control Monday, May 21,

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secrets in source control aren’t secret Monday, May 21, 12

Open source- able? Monday, May 21, 12

Rotateable Secure Keys Monday, May 21, 12

Config: Development $ cat .env S3_KEY=FOONVBAR FACEBOOK_APP_ID=281502345249818 FACEBOOK_SECRET=d59c2a439f4be49cf1 Monday, May

21, 12

Config: Development $ foreman run rails console ruby-1.9.3 > puts

ENV[“S3_KEY”] ruby-1.9.3 > “FOONVBAR” Monday, May 21, 12

Config: Development $ foreman start $ cat Procfile web: bundle

exec unicorn -p $PORT -c ./config/unicorn.rb worker: bundle exec rake jobs:work Monday, May 21, 12

Config: Production • Heroku ‘config’ • Read from environment $

heroku config:add S3_KEY=FOONVBAR > puts ENV[‘S3_KEY’] > “FOONVBAR” Monday, May 21, 12

Config: Production • On A VPS • Use Foreman •

Add values directly to command $ S3_KEY=FOONVBAR rails console ruby-1.9.3 > puts ENV[‘S3_KEY’] ruby-1.9.3 > “FOONVBAR” Monday, May 21, 12

development vs. production Monday, May 21, 12

Development • As close to production as possible • Same

data-stores (postgres, memcache) • Same language versions (Ruby 1.9) • Real/consistent data Monday, May 21, 12

Development • Real/consistent data $ heroku db:pull Monday, May 21,

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Development • Real/consistent data $ rake users:drop $ rake users:create

# ... $ rake master:create Monday, May 21, 12

Bundler • Bundle versions specified • ~> • Use semantic

versioning • Prevent unexpected library changes gem 'twitter', '~> 2.0.2' gem "koala", '~> 1.2.1' gem 'tumblr-api', '~> 0.1.4' # ... Gemfile Monday, May 21, 12

README.md • Living document • Standardize dev environment • Instructions

for external dependencies • Instructions for starting processes • Problem with dev environment? • Put the fix in the readme $ brew install memcache $ foreman start Monday, May 21, 12

but... it worked in development Monday, May 21, 12

Staging • A “production like” environment • Try stuff out

here before production Monday, May 21, 12

Staging [remote "production"] url = [email protected]:hourschool.git fetch = +refs/heads/*:refs/remotes/heroku/* [remote

"staging"] url = [email protected]:hourschool-drama.git fetch = +refs/heads/*:refs/remotes/heroku/* .git/config Monday, May 21, 12

Staging $ git push --remote staging $ cap deploy staging

Monday, May 21, 12

Stage with Data Production Development Staging Monday, May 21, 12

Multiple Staging [remote "production"] # ... [remote "staging"] # ...

[remote "staging-bill"] # ... [remote "staging-ted"] # ... .git/config Monday, May 21, 12

1 app 1 codebase Monday, May 21, 12

Git • All code for the app goes in one

repository • Split out easily reusable code into separate libraries • i.e. github.com/schneems/wicked Monday, May 21, 12

Git Flow • New feature? • Put it in a

branch • Refactoring code? • Put it in a branch • Need a New Demo? • Put it in a branch Monday, May 21, 12

Branches • Keep the codebase clean • Testing feature branches

in staging $ git co -B schneems/solr_search $ git push --remote staging schneems/solr_search:master Monday, May 21, 12

logging Monday, May 21, 12

Logging • Production errors still happen • Tail logs to

find the cause • Use a logging service to dig in deeper $ heroku logs --remote production --tail Monday, May 21, 12

Logging • Record Logs & Errors • New Relic (rpm)

• Scout • Loggly • Papertrails • Airbrake (hoptoad) Monday, May 21, 12

Logging • Help when the problem is intermittent • Too

much traffic for tail to be effective • Provide additional insights Monday, May 21, 12

Error Pages • Admins get error + Backtrace Couldn't find

Course with ID=chunkybacon Details Params: {"action"=>"show", "controller"=>"courses", "id"=>"chunkybacon"} Backtrace: lib/active_record/relation/finder_methods.rb:304:in `find_one' Monday, May 21, 12

Custom Error Pages • Admins get error + Backtrace Couldn't

find Course with ID=chunkybacon Details Params: {"action"=>"show", "controller"=>"courses", "id"=>"chunkybacon"} Backtrace: lib/active_record/relation/finder_methods.rb:304:in `find_one' Monday, May 21, 12

scale out Monday, May 21, 12

Web Instances • Handle web requests • More instances =

more throughput • Worker instances can help offload tasks Monday, May 21, 12

Workers • Push long tasks that don’t fit in request

cycle to a worker • Workers have the same code, but don’t serve web content • Perfect for • Delayed emails • Image Processing • etc. Monday, May 21, 12

Workers • Use with a queuing system • Resque (redis)

• DelayedJob (sql) • Sidekiq • Enqueue from the web server • User signs up, queue email • Dequeue & run on the worker • Process next item in queue Monday, May 21, 12

the web app demystified Monday, May 21, 12

Twelve Factor Monday, May 21, 12

Twelve Factor • Web apps have a contract with their

platform • When the right development methods are used, their app can be cleanly deployed quickly Monday, May 21, 12

Do You Like? • Minimizing new developer overhead? • Running

in multiple environments? • Easily scaling without tooling, architecture or development headaches? • Having the latest updates available to users at a moments notice? Read more at 12factor.net Monday, May 21, 12

Questions? @schneems Monday, May 21, 12

12factor.net • Codebase • One codebase tracked in revision control,

many deploys • Dependencies • Explicitly declare and isolate dependencies • Config • Store config in the environment • Backing Services • Treat backing services as attached resources Monday, May 21, 12

12factor.net • Build, Release, Run • Strictly separate build and

run stages • Process • Execute the app as one or more stateless processes • Port Binding • Export services via port binding • Concurrency • Scale out via the process model Monday, May 21, 12

12factor.net • Disposability • Maximize robustness with fast startup and

graceful shutdown • Dev/Prod Parity • Keep development, staging, and production as similar as possible • Logs • Treat logs as event streams • Admin Process • Run admin/management tasks as one-off processes Monday, May 21, 12