1 files changed, 101 insertions, 0 deletions
diff --git a/lib/gitlab/lfs/client.rb b/lib/gitlab/lfs/client.rb
new file mode 100644
index 00000000000..e4d600694c2
--- /dev/null
+++ b/lib/gitlab/lfs/client.rb
@@ -0,0 +1,101 @@
+# frozen_string_literal: true
+module Gitlab
+  module Lfs
+    # Gitlab::Lfs::Client implements a simple LFS client, designed to talk to
+    # LFS servers as described in these documents:
+    #   * https://github.com/git-lfs/git-lfs/blob/master/docs/api/batch.md
+    #   * https://github.com/git-lfs/git-lfs/blob/master/docs/api/basic-transfers.md
+    class Client
+      attr_reader :base_url
+
+      def initialize(base_url, credentials:)
+        @base_url = base_url
+        @credentials = credentials
+      end
+
+      def batch(operation, objects)
+        body = {
+          operation: operation,
+          transfers: ['basic'],
+          # We don't know `ref`, so can't send it
+          objects: objects.map { |object| { oid: object.oid, size: object.size } }
+        }
+
+        rsp = Gitlab::HTTP.post(
+          batch_url,
+          basic_auth: basic_auth,
+          body: body.to_json,
+          headers: { 'Content-Type' => 'application/vnd.git-lfs+json' }
+        )
+
+        raise BatchSubmitError unless rsp.success?
+
+        # HTTParty provides rsp.parsed_response, but it only kicks in for the
+        # application/json content type in the response, which we can't rely on
+        body = Gitlab::Json.parse(rsp.body)
+        transfer = body.fetch('transfer', 'basic')
+
+        raise UnsupportedTransferError.new(transfer.inspect) unless transfer == 'basic'
+
+        body
+      end
+
+      def upload(object, upload_action, authenticated:)
+        file = object.file.open
+
+        params = {
+          body_stream: file,
+          headers: {
+            'Content-Length' => object.size.to_s,
+            'Content-Type' => 'application/octet-stream'
+          }.merge(upload_action['header'] || {})
+        }
+
+        params[:basic_auth] = basic_auth unless authenticated
+
+        rsp = Gitlab::HTTP.put(upload_action['href'], params)
+
+        raise ObjectUploadError unless rsp.success?
+      ensure
+        file&.close
+      end
+
+      private
+
+      attr_reader :credentials
+
+      def batch_url
+        base_url + '/info/lfs/objects/batch'
+      end
+
+      def basic_auth
+        return unless credentials[:auth_method] == "password"
+
+        { username: credentials[:user], password: credentials[:password] }
+      end
+
+      class BatchSubmitError < StandardError
+        def message
+          "Failed to submit batch"
+        end
+      end
+
+      class UnsupportedTransferError < StandardError
+        def initialize(transfer = nil)
+          super
+          @transfer = transfer
+        end
+
+        def message
+          "Unsupported transfer: #{@transfer}"
+        end
+      end
+
+      class ObjectUploadError < StandardError
+        def message
+          "Failed to upload object"
+        end
+      end
+    end
+  end
+end