Guillaume Champagne focused on improving Docker Compose reliability for the envoyproxy/envoy repository, specifically addressing SELinux bind mount compatibility. He introduced a configurable MOUNT_ACCESS_MODE variable in YAML-based Docker Compose files, allowing SELinux-friendly mount options such as :Z to be set when needed. This approach ensured that the Envoy codebase compiled successfully on Fedora 43 with SELinux enabled, while maintaining backward compatibility for other environments. By targeting a persistent build friction point, Guillaume enhanced cross-distro CI/CD workflows and developer experience. His work demonstrated depth in DevOps and Docker, delivering a targeted bug fix that stabilized builds in complex security contexts.