1 files changed, 115 insertions, 0 deletions
diff --git a/activestorage/lib/active_storage/service/azure_service.rb b/activestorage/lib/active_storage/service/azure_service.rb
new file mode 100644
index 0000000000..a505b9a0ee
--- /dev/null
+++ b/activestorage/lib/active_storage/service/azure_service.rb
@@ -0,0 +1,115 @@
+require "active_support/core_ext/numeric/bytes"
+require "azure/storage"
+require "azure/storage/core/auth/shared_access_signature"
+
+# Wraps the Microsoft Azure Storage Blob Service as a Active Storage service.
+# See `ActiveStorage::Service` for the generic API documentation that applies to all services.
+class ActiveStorage::Service::AzureService < ActiveStorage::Service
+  attr_reader :client, :path, :blobs, :container, :signer
+
+  def initialize(path:, 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
+    @path = path
+  end
+
+  def upload(key, io, checksum: nil)
+    instrument :upload, key, checksum: checksum do
+      begin
+        blobs.create_block_blob(container, key, io, content_md5: checksum)
+      rescue Azure::Core::Http::HTTPError => e
+        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
+        _, io = blobs.get_blob(container, key)
+        io.force_encoding(Encoding::BINARY)
+      end
+    end
+  end
+
+  def delete(key)
+    instrument :delete, key do
+      begin
+        blobs.delete_blob(container, key)
+      rescue Azure::Core::Http::HTTPError
+        false
+      end
+    end
+  end
+
+  def exist?(key)
+    instrument :exist, key do |payload|
+      answer = blob_for(key).present?
+      payload[:exist] = answer
+      answer
+    end
+  end
+
+  def url(key, expires_in:, disposition:, filename:)
+    instrument :url, key do |payload|
+      base_url = url_for(key)
+      generated_url = signer.signed_uri(URI(base_url), false, permissions: "r",
+        expiry: format_expiry(expires_in), content_disposition: "#{disposition}; filename=\"#{filename}\"").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 do |payload|
+      base_url = url_for(key)
+      generated_url = signer.signed_uri(URI(base_url), false, 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 url_for(key)
+      "#{path}/#{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, options = {}, &block)
+      blob = blob_for(key)
+
+      chunk_size = 5.megabytes
+      offset = 0
+
+      while offset < blob.properties[:content_length]
+        _, io = blobs.get_blob(container, key, start_range: offset, end_range: offset + chunk_size - 1)
+        yield io
+        offset += chunk_size
+      end
+    end
+end