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Last active February 19, 2018 16:12
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Lambda@Edge A/B testing - Viewer Request
'use strict';
const sourceCoookie = 'X-Source';
const sourceMain = 'main';
const sourceExperiment = 'experiment';
const experimentTraffic = 0.5;
// Viewer request handler
exports.handler = (event, context, callback) => {
const request = event.Records[0].cf.request;
const headers = request.headers;
// Look for source cookie
if ( headers.cookie ) {
for (let i = 0; i < headers.cookie.length; i++) {
if (headers.cookie[i].value.indexOf(sourceCoookie) >= 0) {
console.log('Source cookie found. Forwarding request as-is');
// Forward request as-is
callback(null, request);
return;
}
}
}
console.log('Source cookie has not been found. Throwing dice...');
const source = ( Math.random() < experimentTraffic ) ? sourceExperiment : sourceMain;
console.log(`Source: ${source}`)
// Add Source cookie
const cookie = `${sourceCoookie}=${source}`
console.log(`Adding cookie header: ${cookie}`);
headers.cookie = headers.cookie || [];
headers.cookie.push({ key:'Cookie', value: cookie });
// Forwarding request
callback(null, request);
};
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