Worked on the mosaicml/composer repository to deliver legacy PyTorch image support within the container build matrix, focusing on Ubuntu 20.04 images with specific CUDA variants. Updated Dockerfiles and CI/CD workflows using Docker, YAML, and Python to integrate these legacy build configurations, enabling comprehensive testing and deployment for older workloads. The approach emphasized infrastructure improvements, ensuring reproducible and reliable container builds while expanding test coverage for legacy environments. Maintained clear, commit-based documentation to support auditability and future maintenance. No major bugs were addressed during this period, as the primary focus remained on enhancing build automation and compatibility for legacy systems.