Configuring ActiveStorage to use S3 via ECS Credentials

Question

I am trying to configure ActiveStorage to use ECS Credentials and can't find any documentation on how to configure it.

Right now I have:

staging:
  service: S3
  region: "MYREGION"
  bucket: "MYBUCKETNAME"
  credentials: Aws::ESCCredentials

But I don't think this is correct?

I am trying to follow the documentation on the ActiveStorage site: https://edgeguides.rubyonrails.org/active_storage_overview.html#s3-service-amazon-s3-and-s3-compatible-apis which leads to https://docs.aws.amazon.com/sdk-for-ruby/v3/api/Aws/S3/Client.html#initialize-instance_method . I just don't know how to set the right value here in the credentials field is.

Answer 1

What worked for me:

In storage.yml:

staging:
  service: S3
  region: "MYREGION"
  bucket: "MYBUCKETNAME"

Then, create an extra file in config/initializers named aws.rb with the following content:

require 'aws-sdk-core'

if Rails.env === 'staging' || Rails.env === 'production'
  Aws.config.update(credentials: Aws::ECSCredentials.new)
end

Of course, the ECS container itself must be setup to include the necessary environment variables (these two resources helped me with that: https://docs.aws.amazon.com/AWSCloudFormation/latest/UserGuide/aws-resource-ecs-taskdefinition.html and Deploying dockerised web-app on AWS with Fargate with terraform)

Hope that this helps others trying to do similar.