Migrating GitHub's Web and API to Kubernetes Running on Bare Metal
Over the last year GitHub has evolved their internal infrastructure that runs the Ruby on Rails application responsible for github.com and api.github.com to run on Kubernetes. The migration began with web and API applications running on Unicorn processes that were deployed onto Puppet-managed bare metal ("metal cloud") servers, and ended with all web and API requests being served by containers running in Kubernetes clusters deployed onto the metal cloud.
According to the GitHub engineering blog, the basic approach to deploying and running GitHub did not significantly change over the initial eight years of operation. However, GitHub itself changed dramatically, with new features, larger software communities, more GitHubbers on staff, and many more requests per second. As the organisation grew, the existing operational approach began to exhibit new problems: many teams wanted to extract the functionality into smaller services that could run and be deployed independently; and as the number of services increased, the SRE team found they were increasingly performing maintenance, which meant there was little time for enhancing the underlying platform.
Read more at InfoQ