Previously I worked on a Data Lake project, where numerous data applications and associated infrastructure had been created over the span of 5+ years. Unfortunately to me, some of these applications were no longer developed, they had been abandoned/moved and to my horror the original developers and devops were no longer part of the project. In addition to everything, the lack of documentation from the client's side, made it challenging, almost impossible, to understand the purpose of the infrastructure and applications.
This is the story of how I managed to decomission 5+ year old data applications and infrastructure that resulted in significant cost and energy savings.