ActivityPubでリモートのオブジェクトをGETするときのリクエストをHTTP Signatureで署名するオプション (#6731)

* Sign ActivityPub GET

* Fix v12, v12.48.0 UI bug

src/services/instance-actor.ts

@@ -0,0 +1,17 @@
+import { createSystemUser } from './create-system-user';
+import { ILocalUser } from '../models/entities/user';
+import { Users } from '../models';
+
+const ACTOR_USERNAME = 'instance.actor' as const;
+
+export async function getInstanceActor(): Promise<ILocalUser> {
+	const user = await Users.findOne({
+		host: null,
+		username: ACTOR_USERNAME
+	});
+
+	if (user) return user as ILocalUser;
+
+	const created = await createSystemUser(ACTOR_USERNAME);
+	return created as ILocalUser;
+}