Add requestContext.sourceIp fallback for missing x-forwarded-for

[nickmeldrum]

The REQUEST.ip property is mapped from the x-forwarded-for header instead of the sourceIp property on the event.requestContext property.

Can you give me the info about why?

The problem I have is when running this in serverless-local to emulate a lambda locally for my testing, the ip comes through as undefined.

[jeremydaly]

Hi @nickmeldrum,

The x-forwarded-for is the standard way to extract IP addresses from a proxy so it was implemented that way. This also works with the new ALB routing (which doesn't have an IP address as part of the request context).

However, I can see the issue with your local use case, so I can add a fallback if the x-forwarded-for is undefined or null.

Thanks for the report,
Jeremy

[nickmeldrum]

interesting thanks - is it right for you to add a fallback or for the serverless-local package to correctly set the x-forwarded-for header i wonder?

[jeremydaly]

Good question, probably the latter. However, I'm adding support for Lambda@Edge functions as well, and according to this documentation (https://docs.aws.amazon.com/AmazonCloudFront/latest/DeveloperGuide/lambda-event-structure.html#lambda-event-structure-request), those events don't contain x-forwarded-for either.

There may need to be a number of fallbacks to normalize the client IP address, so I think it would be worth adding.

[nickmeldrum]

good info cheers