Rock the night

This post details the migration of Spotify's legacy 'users' service to a new 'user2' service. The 'users' service was a scalability bottleneck, handling account creation, login, client settings, and device restrictions. The 'user2' service was introduced with a clustered database to address these limitations. The migration involved a 56-step plan, including pre-migration of data, making the old database read-only, migrating remaining data (which took longer than expected due to overload), and finally switching DNS to direct traffic to the new service. The post also mentions a post-deployment issue with file descriptor limits, which was resolved by increasing the default limit.