Keystone apps

A Keystone instance acts as a function of your schema which creates a GraphQL API for querying and an Admin UI for managing your data:

schema => ({ GraphQL, AdminUI });

Introduction

Here, GraphQL and AdminUI are referred to as Apps.

A Keystone App has two primary purposes

1. Prepare an express-compatible middleware for handling incoming http requests
2. Provide a build() method to create a static production build for this app

At a minimum a Keystone application requires one app, the GraphQL API:

const { GraphQLApp } = require('@keystonejs/app-graphql');
const { Keystone } = require('@keystonejs/keystone');

const keystone = new Keystone();

module.exports = {
  keystone,
  apps: [new GraphQLApp()],
};

Most of the time the GraphQLApp will be paired with an AdminUIApp which provides the functionality of the Keystone Admin UI:

 const { GraphQLApp } = require('@keystonejs/app-graphql');
 const { Keystone } = require('@keystonejs/keystone');
+const { AdminUIApp } = require('@keystonejs/app-admin-ui');

 const keystone = new Keystone();

 module.exports = {
   keystone,
   apps: [
     new GraphQLApp(),
+    new AdminUIApp(),
   ]
 }

In both cases, the keystone dev and keystone start commands will consume the exported .apps array, making their middleware available in the order the apps are specified.

If you're using a Custom Server, it will be your responsibility to ensure each app's middleware is correctly injected into any http server you setup.

Other interesting Keystone compatible Apps are:

• Static App for serving static files.
• Next.js App for serving a Next.js App on the same server as the API

Custom apps

If you need to provide your own custom middleware for your system you can create a custom app and include it in your exported apps.

class CustomApp {
  prepareMiddleware({ keystone, dev, distDir }) {
    const middleware = express();
    return middleware;
  }
}

module.exports = {
  keystone,
  apps: [
    new GraphQLApp(),
    new AdminUIApp(),
    new CustomApp(),
  ],
};