To run our application properly, we need some external dependencies. We can get these dependencies by using a package manager, like npm or yarn.

Some of the packages that we need are as follows:

• koa: Our base framework
• koa-router: RESTful routing middleware for Koa
• koa-logger: Development-style logger middleware for Koa
• koa-body: Request body parser middleware for Koa
• mongoose: Object data modelling (ODM) library for MongoDB and Node.js
• joi: Object schema validation library

To install these dependencies into our application using npm, we use the following command:

npm install --save koa koa-router koa-logger koa-body mongoose joi

The --save flag specifies that we want to save these packages as dependencies in our package.json file.