Exposing the hobnob.yaml file is as simple as adding a new endpoint to our API. However, the specification file is located at spec/openapi/hobnob.yaml, which is outside the dist/ directory of our application. Therefore, first, we should modify our serve script to also copy the OpenAPI specification to the root of the dist/ directory after the application has been built:

"dev:serve": "yarn run build && cp spec/openapi/hobnob.yaml dist/openapi.yaml && dotenv -e envs/.env node dist/index.js",
"serve": "yarn run build && cp spec/openapi/hobnob.yaml dist/openapi.yaml && dotenv -e envs/.env pm2 start dist/index.js",

Now, inside src/index.js, we need to add a new endpoint to retrieve and serve that same openapi.yaml. Add the following to src/index.js.

import fs from 'fs';

...

app.get('/openapi.yaml', (req, res, next) => {
  fs.readFile(`${__dirname}/openapi.yaml`, (err, file) => {
    if (err) {
      res.status(500);
      res.end();
      return next();
    }
    res.write(file);
    res.end();
    return next();
  });
});

Now, whilst running the dev:serve script, open your browser to http://127.0.0.1:8080/openapi.yaml. You should see the OpenAPI specification displayed on the screen!