Get bearer token automatically from API and use it in (Postman as Pre-request scipts)

postman_pre_request_script.js

# Might be useful in Spring boot apps

const postRequest = {
  url: 'http://<URL>/auth/login',
  method: 'POST',
  header: 'Content-Type:application/json',
  body: {
    mode: 'application/json',
    raw: JSON.stringify(
        {
            "username": <username>,
            "password": <password>
        })
  }
};

pm.sendRequest(postRequest, function (err, res) {
    pm.environment.set('accessToken', res.headers.get("X-Access-Token"));
});