Basic HTTP Authentication for CloudFront with Lambda@Edge

lambda-basic-auth.js

'use strict';
exports.handler = (event, context, callback) => {

    // Get request and request headers
    const request = event.Records[0].cf.request;
    const headers = request.headers;

    // Configure authentication
    const authUser = 'user';
    const authPass = 'pass';

    // Construct the Basic Auth string
    const authString = 'Basic ' + new Buffer(authUser + ':' + authPass).toString('base64');

    // Require Basic authentication
    if (typeof headers.authorization == 'undefined' || headers.authorization[0].value != authString) {
        const body = 'Unauthorized';
        const response = {
            status: '401',
            statusDescription: 'Unauthorized',
            body: body,
            headers: {
                'www-authenticate': [{key: 'WWW-Authenticate', value:'Basic'}]
            },
        };
        callback(null, response);
    }

    // Continue request processing if authentication passed
    callback(null, request);
};

See my article on Medium for details.

Thanks Leonid for sharing this.

Lines 8 to 13 if moved before the function (before line 2) it will be parsed just once and cached in memory for next executions.

This should be in the official AWS docs. Extremely useful; thanks for sharing!

Agreed ! There is little documentation on Lambda Edge. Thank you for sharing the code

Imakarov did you finish full doc on how to setup this? I am having hard time implementing this getting errors when assigning role to lambda. Which role should i use and which policies i have to add that role?

@trinath-k

I had the same problem. Your Lambda has to be in N. Virginia (althought that might have changed).

Find the role you assigned to the Lambda Function, and edit the policy "Trust Relationship" to something like this:

{ "Version": "2012-10-17", "Statement": [ { "Effect": "Allow", "Principal": { "Service": [ "edgelambda.amazonaws.com", "lambda.amazonaws.com" ] }, "Action": "sts:AssumeRole" } ] }

This worked for me. AWS Documentation does not explain that very well.

Good Luck !

Hi, I have configured everything. But i still can't access file in my s3 bucket. I am trying to access a file in this s3 bucket. it's only listing the object. I wanted it be able to download or read.

This XML file does not appear to have any style information associated with it. The document tree is shown below.

inventory-endpoints


1000
false

inventory-endpoints-04.06.2018.yaml
2018-04-13T20:40:38.000Z
"b18f7a425f4be500caf2fc7f3107e77c"
10308
STANDARD

Is there a way to set this up on specific directories in the s3 bucket? i.e. domain.com allowed, domain.com/dir triggers auth

@iamwalker In CloudFront, under "Origin Settings", you can set the Origin Path. For example, I'm running an S3 bucket with dev, stage and prod folders. I have one CloudFront distribution for each one.

You should return the callback or wrap the second call to it into a else case.

Hi!

Inspired from this I made my own version which is using a shared cookie secret to allow application to use Authorization header for JWT Bearer tokens. See webscale-oy/aws-cloudfront-basic-auth for Cloudformation templates and documentation.