1 files changed, 165 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/service/azure_storage_service.rb b/activestorage/lib/active_storage/service/azure_storage_service.rb
new file mode 100644
index 0000000000..17cecd891c
--- /dev/null
+++ b/activestorage/lib/active_storage/service/azure_storage_service.rb
@@ -0,0 +1,165 @@
+# frozen_string_literal: true
+
+require "active_support/core_ext/numeric/bytes"
+require "azure/storage"
+require "azure/storage/core/auth/shared_access_signature"
+
+module ActiveStorage
+  # Wraps the Microsoft Azure Storage Blob Service as an Active Storage service.
+  # See ActiveStorage::Service for the generic API documentation that applies to all services.
+  class Service::AzureStorageService < Service
+    attr_reader :client, :blobs, :container, :signer
+
+    def initialize(storage_account_name:, storage_access_key:, container:)
+      @client = Azure::Storage::Client.create(storage_account_name: storage_account_name, storage_access_key: storage_access_key)
+      @signer = Azure::Storage::Core::Auth::SharedAccessSignature.new(storage_account_name, storage_access_key)
+      @blobs = client.blob_client
+      @container = container
+    end
+
+    def upload(key, io, checksum: nil, **)
+      instrument :upload, key: key, checksum: checksum do
+        handle_errors do
+          blobs.create_block_blob(container, key, IO.try_convert(io) || io, content_md5: checksum)
+        end
+      end
+    end
+
+    def download(key, &block)
+      if block_given?
+        instrument :streaming_download, key: key do
+          stream(key, &block)
+        end
+      else
+        instrument :download, key: key do
+          handle_errors do
+            _, io = blobs.get_blob(container, key)
+            io.force_encoding(Encoding::BINARY)
+          end
+        end
+      end
+    end
+
+    def download_chunk(key, range)
+      instrument :download_chunk, key: key, range: range do
+        handle_errors do
+          _, io = blobs.get_blob(container, key, start_range: range.begin, end_range: range.exclude_end? ? range.end - 1 : range.end)
+          io.force_encoding(Encoding::BINARY)
+        end
+      end
+    end
+
+    def delete(key)
+      instrument :delete, key: key do
+        blobs.delete_blob(container, key)
+      rescue Azure::Core::Http::HTTPError => e
+        raise unless e.type == "BlobNotFound"
+        # Ignore files already deleted
+      end
+    end
+
+    def delete_prefixed(prefix)
+      instrument :delete_prefixed, prefix: prefix do
+        marker = nil
+
+        loop do
+          results = blobs.list_blobs(container, prefix: prefix, marker: marker)
+
+          results.each do |blob|
+            blobs.delete_blob(container, blob.name)
+          end
+
+          break unless marker = results.continuation_token.presence
+        end
+      end
+    end
+
+    def exist?(key)
+      instrument :exist, key: key do |payload|
+        answer = blob_for(key).present?
+        payload[:exist] = answer
+        answer
+      end
+    end
+
+    def url(key, expires_in:, filename:, disposition:, content_type:)
+      instrument :url, key: key do |payload|
+        generated_url = signer.signed_uri(
+          uri_for(key), false,
+          service: "b",
+          permissions: "r",
+          expiry: format_expiry(expires_in),
+          content_disposition: content_disposition_with(type: disposition, filename: filename),
+          content_type: content_type
+        ).to_s
+
+        payload[:url] = generated_url
+
+        generated_url
+      end
+    end
+
+    def url_for_direct_upload(key, expires_in:, content_type:, content_length:, checksum:)
+      instrument :url, key: key do |payload|
+        generated_url = signer.signed_uri(
+          uri_for(key), false,
+          service: "b",
+          permissions: "rw",
+          expiry: format_expiry(expires_in)
+        ).to_s
+
+        payload[:url] = generated_url
+
+        generated_url
+      end
+    end
+
+    def headers_for_direct_upload(key, content_type:, checksum:, **)
+      { "Content-Type" => content_type, "Content-MD5" => checksum, "x-ms-blob-type" => "BlockBlob" }
+    end
+
+    private
+      def uri_for(key)
+        blobs.generate_uri("#{container}/#{key}")
+      end
+
+      def blob_for(key)
+        blobs.get_blob_properties(container, key)
+      rescue Azure::Core::Http::HTTPError
+        false
+      end
+
+      def format_expiry(expires_in)
+        expires_in ? Time.now.utc.advance(seconds: expires_in).iso8601 : nil
+      end
+
+      # Reads the object for the given key in chunks, yielding each to the block.
+      def stream(key)
+        blob = blob_for(key)
+
+        chunk_size = 5.megabytes
+        offset = 0
+
+        raise ActiveStorage::FileNotFoundError unless blob.present?
+
+        while offset < blob.properties[:content_length]
+          _, chunk = blobs.get_blob(container, key, start_range: offset, end_range: offset + chunk_size - 1)
+          yield chunk.force_encoding(Encoding::BINARY)
+          offset += chunk_size
+        end
+      end
+
+      def handle_errors
+        yield
+      rescue Azure::Core::Http::HTTPError => e
+        case e.type
+        when "BlobNotFound"
+          raise ActiveStorage::FileNotFoundError
+        when "Md5Mismatch"
+          raise ActiveStorage::IntegrityError
+        else
+          raise
+        end
+      end
+  end
+end