Maybe/config/storage.yml

local:
  service: Disk
  root: <%= Rails.root.join("storage") %>

test:
  service: Disk
  root: <%= Rails.root.join("tmp/storage") %>

amazon:
  service: S3
  access_key_id: <%= ENV["S3_ACCESS_KEY_ID"] %> 
  secret_access_key: <%= ENV["S3_SECRET_ACCESS_KEY"] %>
  region: <%= ENV["S3_REGION"] || "us-east-1" %>
  bucket: <%= ENV["S3_BUCKET"] %>
google:
  service: GCS
  project: <%= ENV["GCS_PROJECT"] %>
  credentials: <%= Rails.root.join("gcp-storage-keyfile.json") %>
  bucket: <%= ENV["GCS_BUCKET"] %> 

azure:
  service: AzureStorage
  storage_account_name: <%= ENV["AZURE_STORAGE_ACCOUNT_NAME"] %>
  storage_access_key: <%= ENV["AZURE_STORAGE_ACCESS_KEY"] %>
  container: <%= ENV["AZURE_STORAGE_CONTAINER"] %>