metadataテーブルにexpires_atカラムを追加

メタデータの有効期限が現在より過去の場合、メタデータを再取得する

database/migrations/2019_01_15_143800_add_expires_on_metadata.php

@@ -0,0 +1,32 @@
+<?php
+
+use Illuminate\Support\Facades\Schema;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Database\Migrations\Migration;
+
+class AddExpiresOnMetadata extends Migration
+{
+    /**
+     * Run the migrations.
+     *
+     * @return void
+     */
+    public function up()
+    {
+        Schema::table('metadata', function (Blueprint $table) {
+            $table->timestamp('expires_at')->nullable();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     *
+     * @return void
+     */
+    public function down()
+    {
+        Schema::table('metadata', function (Blueprint $table) {
+            $table->removeColumn('expires_at');
+        });
+    }
+}