Sample code: how to refresh session of Cognito User Pools with Node.js and Express

authorize.js

const AWS = require('aws-sdk');
const CognitoUserPool = require('amazon-cognito-identity-js-node').CognitoUserPool;
const CognitoUserSession = require('amazon-cognito-identity-js-node').CognitoUserSession;
const CognitoUser = require('amazon-cognito-identity-js-node').CognitoUser;
const CognitoIdToken = require('amazon-cognito-identity-js-node').CognitoIdToken;
const CognitoAccessToken = require('amazon-cognito-identity-js-node').CognitoAccessToken;
const CognitoRefreshToken = require('amazon-cognito-identity-js-node').CognitoRefreshToken;

const cfg = require('config').config;
const COGNITO_IDENTITY_POOL_ID = cfg.COGNITO_IDENTITY_POOL_ID;
const COGNITO_USER_POOL_ID = cfg.COGNITO_USER_POOL_ID;
const COGNITO_CLIENT_ID = cfg.COGNITO_CLIENT_ID;
const AWS_API_GATEWAY_HOSTNAME = cfg.AWS_API_GATEWAY_HOSTNAME;
const AWS_REGION = cfg.AWS_REGION;


// Redirect to "/login" if a user is not logged-in.
exports.authorize = require('connect-ensure-login').ensureLoggedIn('/login');


exports.authorizeUser = function(req, res, next) {
  AWS.config.region = AWS_REGION;
  const tokens = req.user.tokens;
  AWS.config.credentials = getCognitoIdentityCredentials(tokens);
  AWS.config.credentials.get(function(err) {
    if (err) throw err;
    req.session.identityId = AWS.config.credentials.identityId;
    const credentials = AWS.config.credentials.data.Credentials;
    req.session.AWSCredentials = getAWSCredentials(credentials);
    next();
  });
};


exports.checkTokenExpiration = function(req, res, next) {
  const AccessToken = new CognitoAccessToken({AccessToken: req.user.tokens.accessToken});
  const IdToken = new CognitoIdToken({IdToken: req.user.tokens.idToken});
  const RefreshToken = new CognitoRefreshToken({RefreshToken: req.user.tokens.refreshToken});
  const sessionData = {
    IdToken: IdToken,
    AccessToken: AccessToken,
    RefreshToken: RefreshToken
  };
  const cachedSession = new CognitoUserSession(sessionData);

  if (cachedSession.isValid()) {
    next();
  } else {
    cognitoUser = getCognitoUser(req);
    cognitoUser.refreshSession(RefreshToken, (err, session) => {
      if (err) throw err;
      const tokens = getTokens(session);
      AWS.config.credentials = getCognitoIdentityCredentials(tokens);
      AWS.config.credentials.get(function() {
        const credentials = AWS.config.credentials.data.Credentials;
        req.session.AWSCredentials = getAWSCredentials(credentials);
        next();
      });
    });
  }
};


getCognitoUser = function(req) {
  const poolData = { 
    UserPoolId : COGNITO_USER_POOL_ID,
    ClientId : COGNITO_CLIENT_ID
  };
  const userPool = new CognitoUserPool(poolData);
  const userData = {
    Username : req.user.email, 
    Pool : userPool
  };
  return new CognitoUser(userData);
};


getTokens = function(session) {
  return {
    accessToken: session.getAccessToken().getJwtToken(),
    idToken: session.getIdToken().getJwtToken(),
    refreshToken: session.getRefreshToken().getToken()
  };
};


getCognitoIdentityCredentials = function(tokens) {
  const loginInfo = {};
  loginInfo[`cognito-idp.${AWS_REGION}.amazonaws.com/${COGNITO_USER_POOL_ID}`] = tokens.idToken;
  const params = {
    IdentityPoolId: COGNITO_IDENTITY_POOL_ID,
    Logins: loginInfo
  };
  return new AWS.CognitoIdentityCredentials(params);
};


getAWSCredentials = function(credentials) {
  return {
    accessKey: credentials.AccessKeyId,
    secretKey: credentials.SecretKey,
    sessionToken: credentials.SessionToken,
    region: AWS_REGION,
    invokeUrl: 'https://' + AWS_API_GATEWAY_HOSTNAME
  };
};