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How to Migrate from AWS S3 to DigitalOcean Spaces in Rails 6

Picture of railroad tracks. (Morant's Curve in Banff National Park, Canada)

Oct 3, 2020

DigitalOcean Spaces is a convenient way to store files. It might be cheaper than AWS S3, depending on your use case. Luckily, the APIs are compatible, so switching is simple. I recently migrated a Rails 6 project that was using AWS S3 to DigitalOcean Spaces.

Generate Spaces API Keys

The first step is to generate DigitalOcean Spaces API keys to use in your Rails 6 app. In DigitalOcean, click on API in the left pane, then click Generate New Key next to 'Spaces access keys'
DigitalOcean Spaces Screenshot2

Write these keys down and save them for later.

Edit Rails Credentials

Next, we need to add the DigitalOcean Spaces API keys and credentials to Rails. Using Rails Credentials is a secure way to manage them in Rails 6.
In your rails project directory, type rails credentials:edit
You will see something like this if you've been using Rails Credentials with AWS already:

 aws:
   access_key_id: ACCESS_KEY_GOES_HERE
   secret_access_key: SECRET_ACCESS_KEY_GOES_HERE

Add your DigitalOcean Spaces information under a new digitalocean section in the file. You can delete the aws section later if it isn't needed.

 aws:
   access_key_id: ACCESS_KEY_GOES_HERE
   secret_access_key: SECRET_ACCESS_KEY_GOES_HERE

 digitalocean:
   access_key_id: ACCESS_KEY_GOES_HERE
   secret_access_key: SECRET_ACCESS_KEY_GOES_HERE
   endpoint: https://REGION.digitaloceanspaces.com
   region: REGION
   bucket: BUCKET_NAME

The access_key_id and secret_access_key are what you generated in the previous step
endpoint is from the URL of your Space. You can find it under the title of your Space if you remove the project. Include https:// in the config field.
region can also be found in the URL of your Space.
bucket is the name of your Space.
DigitalOcean Spaces Screenshot

If you look closely, you can see a single space character before aws: and before digitalocean:. That space cost me an hour of my life. I'm not bitter.

Makes Rails Use DigitalOcean Spaces

Now we need to make ActiveStorage in Rails use the DigitalOcean Spaces information we just added to our Rails Credentials. To do that, we need to edit storage.yml.

digitalocean:
  service: S3
  access_key_id: \<\%\= Rails.application.credentials.dig(:digitalocean, :access_key_id) \%\>
  secret_access_key: \<\%\= Rails.application.credentials.dig(:digitalocean, :secret_access_key) \%\>
  region: \<\%\= Rails.application.credentials.dig(:digitalocean, :region) \%\>
  bucket: \<\%\= Rails.application.credentials.dig(:digitalocean, :bucket) \%\>
  endpoint: \<\%\= Rails.application.credentials.dig(:digitalocean, :endpoint) \%\>

<\%= Rails.application.credentials.dig(:digitalocean, :access_key_id) \%> means look in the Rails credentials file, under the digitalocean section, for the access_key_id field. Edit those if you used different names than in this tutorial.
The service is still S3. That isn't a typo. It's because DigitalOcean Spaces has an API compatible with S3 and Rails hasn't made an official service name for Spaces yet.
Make sure to remove or comment out the AWS/Amazon section of storage.yml if you were using it before.
Then, we need to edit our environments to use DigitalOcean Spaces. I would recommend editing development.rb first to test your changes. Most likely you'll want to set it to store files on your local disk, but for testing, we can set it to use DigitalOcean Spaces. That way, we won't have to test in the production environment.

Update this line in development.rb

  config.active_storage.service = :digitalocean

It is set to :digitalocean because that's what we defined in storage.yml

Test to make sure it works, then update the same line in production.rb

You probably want to change it back to store locally for the development environment. Change it to :local in development.rb to do that.

  config.active_storage.service = :local

That's it. That's all it takes to migrate a Rails 6 project from AWS S3 to DigitalOcean Spaces.

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