AWS lambda serverless website session maintaining

Question

I developed a website using node.js as back-end. Recently I am trying to make it serverless and deploy to lambda. I will re-write most of my code but just haven't figured out how to maintain the session after user logged in. I was using "express-session" module and the session data is all recorded in the database.

To be honest I don't have a very deep understanding on sessions. I searched on google and did not find what I need. Does anyone have some sample code on maintaining sessions using lambda? or any resources. Thanks a lot!

Answer 1

Either you use Cognito or your own way of session management, beware that lambda calls share their runtime and share static state between them. Make sure that your design considers this fact and architect your session sharing accordingly.

https://www.linkedin.com/pulse/does-lambda-call-share-any-commonstate-santhosh-gandhe/

Answer 2

In the Amazon Cognito Identity SDK for Javascript, check in particular the use case 16, it shows how to retrieve the Cognito current user. You can use this function to pass from page to page the current user attributes.

    var poolData = {
        UserPoolId : '...', // Your user pool id here
        ClientId : '...' // Your client id here
    };
    var userPool = new AWSCognito.CognitoIdentityServiceProvider.CognitoUserPool(poolData);
    var cognitoUser = userPool.getCurrentUser();

    if (cognitoUser != null) {
        cognitoUser.getSession(function(err, session) {
            if (err) {
                alert(err);
                return;
            }
            console.log('session validity: ' + session.isValid());
            // other AWS actions ...
        });
    }