Carrierwave AWS S3 Guide

A (mostly) pain-free guide to using AWS S3 to store images for your rails app.

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This guide will walk you through the process of setting up the carrierwave gem along with fog to enable image uploading to Amazon S3 for your Ruby on Rails projects.

This guide assumes knowledge of Ruby on Rails gems, installation and usage. I am using the example of adding images to a room listing for a apartment-sharing service, you should, of course, customise it to your needs.

Why AWS?

To be written

Add the gems into your Gemfile:

gem 'carrierwave' gem 'fog'

then run:

bundle install

To incorporate carrierwave into your project, generate an uploader:

rails generate uploader images

and a migration for the model:

rails g migration add_images_to_rooms image:string

mount the uploader in the model:

mount_uploader :image, ImagesUploader

Next we'll configure carrierwave, as well as fog.

In the image_uploader.rb file in /app/uploaders add:

if Rails.env.production?
  storage :fog
else
  storage :file
end
  
def extension_whitelist
  %w(jpg jpeg gif png)
end

if you want to upload to AWS even in deveopment, remove the if statement if Rails.env.production?

To add the image upload button, in your form, add:

<div class="field">
  <%= f.label :image %>
  <%= f.file_field :image %>
</div>

To make the image display on the page, add this to your view:

<%= image_tag room.image.url if room.image? %>

To implement AWS:

First sign up for Amazon Web Services - there should be an option for a free trial.

Then, navigate to the S3 console, and create a bucket in your region of choice, and use the security credentials page to generate your access keys. Note down both the access key ID and the secret key! Finally, make sure you have "AmazonS3FullAccess" and "AmazonS3ReadOnlyAccess" in your policy permissions.

create a carrier_wave.rb file in config/initializers/carrier_wave.rb

if Rails.env.production?
  CarrierWave.configure do |config|
    config.fog_credentials = {
      # Configuration for Amazon S3
      :provider              => 'AWS',
      :aws_access_key_id     => ENV['S3_ACCESS_KEY'],
      :aws_secret_access_key => ENV['S3_SECRET_KEY'],
      :region                => ENV['S3_REGION']
    }
    config.fog_directory     =  ENV['S3_BUCKET']
  end
end

Make sure to put in your S3 region:

AWS Regions:

Code	Name
us-east-1	US East (N. Virginia)
us-east-2	US East (Ohio)
us-west-1	US West (N. California)
us-west-2	US West (Oregon)
ca-central-1	Canada (Central)
eu-west-1	EU (Ireland)
eu-central-1	EU (Frankfurt)
eu-west-2	EU (London)
ap-northeast-1	Asia Pacific (Tokyo)
ap-northeast-2	Asia Pacific (Seoul)
ap-southeast-1	Asia Pacific (Singapore)
ap-southeast-2	Asia Pacific (Sydney)
ap-south-1	Asia Pacific (Mumbai)
sa-east-1	South America (São Paulo)

If you are deploying to heroku, use these heroku config settings:

$ heroku config:set S3_ACCESS_KEY=<access key>
$ heroku config:set S3_SECRET_KEY=<secret key>
$ heroku config:set S3_BUCKET=<bucket name>
$ heroku config:set S3_REGION=<region name>