Delivering Travel Deals across 110 Markets Using Amazon CloudFront with Skyscanner

Skyscanner is a global leader in travel that connects over 100 million travelers each month with more than 1,200 trusted travel partners so that travelers can find the best flight, hotel, or car-hire options. Founded in 2003, Skyscanner has offices worldwide, in Europe, Asia-Pacific, and North America, where traveler-first innovations are developed and powered by data and insights. The company is committed to helping shape a more responsible future for travel in collaboration with its partners and by making use of the latest technology so that every traveler can explore the world effortlessly for generations to come.

As Skyscanner has grown to serve over 110 market domains, the company wanted to support engineering efficiency and productivity while optimizing its cloud spend. Although Skyscanner had invested in AWS technologies, it used a fully managed CDN solution from another provider. “One of the major challenges of this project was that we were untangling almost a decade’s worth of root configurations that our team had not implemented,” says Stuart Ross, senior engineering manager at Skyscanner.

Another challenge that the Skyscanner team faced was migrating its CDN to AWS without degrading the customer experience. On any given day, Skyscanner can receive up to 1.5 billion API requests, representing about 24 TB of data. With such high demand, it was essential to avoid global incidents and downtime.

Skyscanner engaged the AWS team to create a proof of concept (POC) for Amazon CloudFront. “The AWS team was amazing,” says Andrew Aylett, senior software engineer at Skyscanner. “We had the opportunity to talk to subject-matter experts to determine which AWS services would be the best fit for our road map.” During the 3-month POC phase, the Skyscanner team built customized configurations, including a serverless image-management handler that automatically compresses static images in the most cost-effective format. “That aspect was previously managed by our CDN provider, and we wanted Amazon CloudFront to have the same capabilities,” says Rory McCann, senior software engineer at Skyscanner.

To set up these configurations, Skyscanner used the AWS Cloud Development Kit (AWS CDK), giving its team the ability to define its cloud application resources using familiar programming languages. “AWS CDK was key to this project,” says Aylett. “Our teams could write code rather than writing infrastructure.” Skyscanner sourced code for its configurations from the AWS Solutions Library, which provides vetted solutions and guidance for business and technical use cases. By making these resources available to its engineering teams, Skyscanner configured Amazon CloudFront with 1,000 lines of code—a significant reduction from its previous solution, which had over 26,000 lines.

Skyscanner also configured Amazon CloudFront for multiregion deployment, increasing its fault tolerance. “Our team can sleep at night knowing that if something happened, there would be another AWS Region where we could automatically direct our web traffic,” says Ross. Protecting its front-facing applications and website from distributed denial-of-service attacks was a priority, too, so the Skyscanner team implemented AWS Shield, a managed distributed denial-of-service protection service that safeguards applications running on AWS. The team activated AWS Shield Advanced so that it has near-real-time visibility into distributed denial-of-service events and 24/7 support from the AWS Shield Response Team.

After completing the POC, the Skyscanner team migrated its front-facing applications and website to Amazon CloudFront in increments, starting with its less-trafficked market domains. “It built up our confidence to start pushing the rest of our traffic from our consumer-facing sites to Amazon CloudFront,” says Aylett. The migration took a total of 3 months to complete, during which the Skyscanner team experienced zero global downtime. Since then, the Skyscanner team has been able to scale its serverless image handler to three billion monthly API requests while maintaining an average cache-hit rate of 99.99 percent. And by running its image handler on a serverless architecture, the Skyscanner team reduced its CDN costs by 50 percent.