Explore the challenges and solutions of migrating a large PHP application between cloud providers in this PHP UK Conference 2017 talk. Gain insights into infrastructure and code evolution, migration steps, cost analysis, and common issues encountered during the transition from Rackspace to Amazon. Learn about codebase migration, Platform as a Service components, WS SDK implementation, bastion host setup, caching strategies, backup solutions, and handling static assets and user-generated content. Discover techniques for media asset management, monitoring, autoscaling, and fuel migration. Delve into cost reduction strategies, macro services implementation, API call rationalization, and the benefits of upgrading to PHP 7. Conclude with a Q&A session to address specific migration concerns and best practices.