Little Ruby trick that made my night:

module ApiError
  HttpExceptions = [
    RestClient::Exception,
    SystemCallError,
    SocketError,
    EOFError,
    Timeout::Error,

Here are the slides for my talk on zero downtime deploys for Rails applications, presented at RailsConf 2012.

Really glad I had the opportunity to present here; hoping this will get people motivated to start thinking about the topic, and change the way we address the issues described there.

Hot compatibility doesn’t only apply to database migrations. Modern web applications can have a wide range of dependencies that without proper planning will break your deploy in subtle, unexpected ways.

Lets understand the challenge of changing a Rails database without introducing any downtime with a simple, apparently harmless migration:

class ApparentlyHarmlessMigration < ActiveRecord::Migration

Relying on migrations to setup your Rails database when you have multiple branches is pretty hard. And slow. And blows away your data.

Instead I decided to simply have one database for each branch, defaulting to master. So this is my new database.yml: