General helper methods - Amazon CloudFront
edgeLocation metadatarawQueryString() method
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General helper methods

This page provides additional helper methods inside CloudFront Functions. To use these methods, create a CloudFront function using JavaScript runtime 2.0.

import cf from 'cloudfront';

For more information, see JavaScript runtime 2.0 features for CloudFront Functions.

edgeLocation metadata

This method requires using the cloudfront module.

Note

You can only use this method for viewer-request functions. For viewer-response functions, this method is empty.

Use this JavaScript object to obtain the edge location airport code, expected Regional Edge Cache region or the CloudFront server IP address used to handle the request. This metadata is available only the viewer request event trigger.

cf.edgeLocation = {
    name: SEA
    serverIp: 1.2.3.4
    region: us-west-2
}

The cf.edgeLocation object can contain the following:

name

The three-letter IATA code of the edge location that handled the request.

serverIp

The IPv4 or IPv6 address of the server that handled the request.

region

The CloudFront Regional Edge Cache (REC) that the request is expected to use if there is a cache miss. This value is not updated in the event that the expected REC is unavailable and a backup REC is used for the request. This doesn't include the Origin Shield location being used, except in cases when the primary REC and the Origin Shield are the same location.

Note

CloudFront Functions isn't invoked a second time when CloudFront is configured to use origin failover. For more information, see Optimize high availability with CloudFront origin failover.

rawQueryString() method

This method doesn't require the cloudFront module.

Use the rawQueryString() method to retrieve the unparsed and unaltered query string as a string.

Request

function handler(event) {
    var request = event.request;
    const qs = request.rawQueryString();
}

Response

Returns the full query string of the incoming request as a string value without the leading ?.

  • If there isn't a query string, but the ? is present, the functions returns an empty string.

  • If there isn't a query string and the ? isn't present, the function returns undefined.

Case 1: Full query string returned (without leading ?)

Incoming request URL: https://example.com/page?name=John&age=25&city=Boston

rawQueryString() returns: "name=John&age=25&city=Boston"

Case 2: Empty string returned (when ? is present but without parameters)

Incoming request URL: https://example.com/page?

rawQueryString() returns: ""

Case 3: undefined returned (no query string and no ?)

Incoming request URL: https://example.com/page

rawQueryString() returns: undefined