UserSigninHandlerAWSLambda.js

import AWS from 'aws-sdk';
import { CognitoUserPool, AuthenticationDetails, CognitoUser } from 'amazon-cognito-identity-js';

export default function signinHandler(body) {
  const authData = JSON.parse(body);
  AWS.config.region = 'us-east-1';
  const authenticationDetails = {
    Username: authData.username,
    Password: authData.password,
  };

  const poolData = {
    UserPoolId: 'us-east-1_xxxxx',
    ClientId: 'xxxxxxxxxxxxxxxxxx'
  };

  const authDetails = new AuthenticationDetails(authenticationDetails);
  const userPool = new CognitoUserPool(poolData);
  const userData = {
    Username: authData.username,
    Pool: userPool,
  };
  const cognitoUser = new CognitoUser(userData);

  return new Promise((resolve, reject) => {
    cognitoUser.authenticateUser(authDetails, {
      onSuccess(result) {
        const response = {
          statusCode: 200,
          headers: {
            'Content-Type': 'application/json',
          },
          body: JSON.stringify({
            token: result.getIdToken().getJwtToken(),
            authenticated: true,
          }),
          isBase64Encoded: false,
        };
        return resolve(response);
      },

      onFailure(error) {
        const response = {
          statusCode: 200,
          headers: {'Content-Type': 'application/json'},
          body: JSON.stringify({ error, authenticated: false }),
          isBase64Encoded: false,
        };
        return reject(response);
      },
    });
  });
}

exports.signin = async (event, context, callback) => {
  try {
    const response = await signinHandler(event.body);
    callback(null, response);
  } catch (error) {
    callback(error);
  }
};