первый коммит, надеюсь последний.

Сделанно:
1. минимально рабочий бэк
2. 2 модели
3. 1 миграция

app/models/index.js

@@ -0,0 +1,38 @@
+const config = require("../config/db.config.js");
+
+const Sequelize = require("sequelize");
+const sequelize = new Sequelize(
+    config.DB,
+    config.USER,
+    config.PASSWORD,
+    {
+        host: config.HOST,
+        dialect: config.dialect,
+        pool: {
+            max: config.pool.max,
+            min: config.pool.min,
+            acquire: config.pool.acquire,
+            idle: config.pool.idle
+        },
+        logging: false
+    }
+);
+
+const db = {};
+
+db.Sequelize = Sequelize;
+db.sequelize = sequelize;
+
+db.user = require("../models/user.model.js")(sequelize, Sequelize);
+db.role = require("../models/role.model.js")(sequelize, Sequelize);
+
+db.role.belongsToMany(db.user, {
+    through: "user_roles"
+});
+db.user.belongsToMany(db.role, {
+    through: "user_roles"
+});
+
+db.ROLES = ["user", "admin", "moderator"];
+
+module.exports = db;

app/models/role.model.js

@@ -0,0 +1,11 @@
+module.exports = (sequelize, Sequelize) => {
+    return sequelize.define("roles", {
+        id: {
+            type: Sequelize.INTEGER,
+            primaryKey: true
+        },
+        name: {
+            type: Sequelize.STRING
+        }
+    });
+};

app/models/user.model.js

@@ -0,0 +1,13 @@
+module.exports = (sequelize, Sequelize) => {
+    return sequelize.define("users", {
+        username: {
+            type: Sequelize.STRING
+        },
+        email: {
+            type: Sequelize.STRING
+        },
+        password: {
+            type: Sequelize.STRING
+        }
+    });
+};