The text discusses the evolution of Java application deployment from using single deployment units like WARs, JARs, and EARs to adopting microservices architecture, facilitated by Docker. It explains how Docker simplifies the process of upgrading services by allowing developers to create new Docker images with updated deployment units instead of redeploying entire applications. The author reviews three methods for building Docker images for Java applications: package-only builds, normal Docker builds, and multi-stage builds, highlighting multi-stage builds as the most efficient approach. Multi-stage builds create smaller images by only including necessary components, which is beneficial for cloud storage. The text also includes a practical guide with commands and a link to a GitHub repository for users to follow along, promising future discussions on handling caching issues in Java builds.