1 files changed, 96 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/service/s3_service.rb b/activestorage/lib/active_storage/service/s3_service.rb
new file mode 100644
index 0000000000..ca461c2994
--- /dev/null
+++ b/activestorage/lib/active_storage/service/s3_service.rb
@@ -0,0 +1,96 @@
+require "aws-sdk"
+require "active_support/core_ext/numeric/bytes"
+
+# Wraps the Amazon Simple Storage Service (S3) as a Active Storage service.
+# See `ActiveStorage::Service` for the generic API documentation that applies to all services.
+class ActiveStorage::Service::S3Service < ActiveStorage::Service
+  attr_reader :client, :bucket, :upload_options
+
+  def initialize(access_key_id:, secret_access_key:, region:, bucket:, upload: {}, **options)
+    @client = Aws::S3::Resource.new(access_key_id: access_key_id, secret_access_key: secret_access_key, region: region, **options)
+    @bucket = @client.bucket(bucket)
+
+    @upload_options = upload
+  end
+
+  def upload(key, io, checksum: nil)
+    instrument :upload, key, checksum: checksum do
+      begin
+        object_for(key).put(upload_options.merge(body: io, content_md5: checksum))
+      rescue Aws::S3::Errors::BadDigest
+        raise ActiveStorage::IntegrityError
+      end
+    end
+  end
+
+  def download(key)
+    if block_given?
+      instrument :streaming_download, key do
+        stream(key, &block)
+      end
+    else
+      instrument :download, key do
+        object_for(key).get.body.read.force_encoding(Encoding::BINARY)
+      end
+    end
+  end
+
+  def delete(key)
+    instrument :delete, key do
+      object_for(key).delete
+    end
+  end
+
+  def exist?(key)
+    instrument :exist, key do |payload|
+      answer = object_for(key).exists?
+      payload[:exist] = answer
+      answer
+    end
+  end
+
+  def url(key, expires_in:, disposition:, filename:, content_type:)
+    instrument :url, key do |payload|
+      generated_url = object_for(key).presigned_url :get, expires_in: expires_in,
+        response_content_disposition: "#{disposition}; filename=\"#{filename}\"",
+        response_content_type: content_type
+
+      payload[:url] = generated_url
+
+      generated_url
+    end
+  end
+
+  def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
+    instrument :url, key do |payload|
+      generated_url = object_for(key).presigned_url :put, expires_in: expires_in,
+        content_type: content_type, content_length: content_length, content_md5: checksum
+
+      payload[:url] = generated_url
+
+      generated_url
+    end
+  end
+
+  def headers_for_direct_upload(key, content_type:, checksum:, **)
+    { "Content-Type" => content_type, "Content-MD5" => checksum }
+  end
+
+  private
+    def object_for(key)
+      bucket.object(key)
+    end
+
+    # Reads the object for the given key in chunks, yielding each to the block.
+    def stream(key, options = {}, &block)
+      object = object_for(key)
+
+      chunk_size = 5.megabytes
+      offset = 0
+
+      while offset < object.content_length
+        yield object.read(options.merge(range: "bytes=#{offset}-#{offset + chunk_size - 1}"))
+        offset += chunk_size
+      end
+    end
+end