Removing dependency tangles in the Atlassian Platform for increased reliability and recoverability

This post details the CPR program's approach to breaking circular dependencies in Atlassian's PaaS. It introduces the 'Layer Cake' model for restructuring infrastructure into ordered layers, emphasizing that components in layer N can only have hard dependencies on lower layers (N-1). It also describes the use of data-driven analysis (surveys, dependency mapping) and tabletop exercises to identify and prioritize risks. Specific risk categories like deployment, source code, artifacts, and build dependencies are discussed, along with pragmatic solutions such as developing low-level provisioning tools and Git mirroring solutions.