title: 'swagger', // page title
oauthOptions: {}, // passed to initOAuth
swaggerOptions: { // passed to SwaggerUi()
  dom_id: 'swagger-ui-container',
  url: 'http://petstore.swagger.io/v2/swagger.json', // link to swagger.json
  supportedSubmitMethods: ['get', 'post', 'put', 'delete', 'patch'],
  docExpansion: 'none',
  jsonEditor: false,
  defaultModelRendering: 'schema',
  showRequestHeaders: false,
  swaggerVersion: 'x.x.x' // read from package.json,
  validatorUrl: null, // disable swagger-ui validator
},
routePrefix: '/docs', // route where the view is returned
specPrefix: '/docs/spec', // route where the spec is returned
exposeSpec: false, // expose spec file
hideTopbar: false, // hide swagger top bar
favicon: '/favicon.png', // default favicon
customCSS: `h1 { color: red }`, // Add Custom CSS on the html

import Koa from 'koa';
import { koaSwagger } from 'koa2-swagger-ui';

const app = new Koa();

app.use(
  koaSwagger({
    routePrefix: '/swagger', // host at /swagger instead of default /docs
    swaggerOptions: {
      url: 'http://petstore.swagger.io/v2/swagger.json', // example path to json
    },
  }),
);

app.listen(3000);

const Koa = require('koa');
const Router = require('koa-router');
const yamljs = require('yamljs');
const koaSwagger = require('koa2-swagger-ui');

const router = new Router({ prefix: '/' });

const app = new Koa();
const router = new Router();

// .load loads file from root.
const spec = yamljs.load('./openapi.yaml');

// example 1 using router.use()
router.use(koaSwagger({ swaggerOptions: { spec } }));

// example 2 using more explicit .get()
router.get('/docs', koaSwagger({ routePrefix: false, swaggerOptions: { spec } }));

app.use(router.routes());
app.listen(3000);