Deploying on multiple EC2 servers with Capistrano

Posted on 04 Aug 2014 by Eric Oestrich

For SmartChat we were deploying on EC2. There were three types of serveers to deploy and I used EC2 tags and capistrano to deploy to each server correctly without having to hardcode any of the servers.

Here is my EC2 console with a custom Type key.

EC2 Console with tags

In the deploy script for production we can now use the AWS SDK to pull your instances down and deploy to them correctly.

Dotenv is used because AWS keys are stored in .env and capistrano won't load that normally.

config/deploy/production.md
require 'aws-sdk'
require 'dotenv'
Dotenv.load

set :rails_env, "production"

primary = true

ec2 = AWS::EC2.new
ec2.instances.tagged("Type").tagged_values("web").each do |instance|
  next unless instance.status == :running

  # We only want one application server migrating the database
  server instance.public_dns_name, :web, :app, :db, :primary => primary

  primary = false
end

ec2.instances.tagged("Type").tagged_values("worker").each do |instance|
  next unless instance.status == :running
  server instance.public_dns_name, :worker, :app
end

ec2.instances.tagged("Type").tagged_values("scheduler").each do |instance|
  next unless instance.status == :running
  server instance.public_dns_name, :scheduler, :app
end
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