Container Images

The booking service jar, with every starter the service now uses, is 40,286,644 bytes. When we split it into its parts, the libraries took 40,051,080 bytes in 92 files. The code we wrote, with its settings, took 17,618 bytes.

Then we changed one line of text in one controller, rebuilt, and split the jar again. The 92 library files were byte for byte the same. Only the 18 KB part had changed.

Those numbers explain how a Spring Boot service should be packaged for a container platform. The sections below explain container images and the layers Spring Boot defines