This paper presents GLAS (Git-based Lab Automated Scheduler or Get Lab Automation Simplified), an open-source, robust, and highly expandable Git-based architecture designed for laboratory automation. GLAS can be deployed in both partially and fully automated experimental science laboratories, enabling the development of a multi-layer scheduling system while maintaining a systematic architecture grounded in a Git repository. We demonstrate the applicability of GLAS through case studies from the Swiss Cat+ automated chemistry laboratory, showcasing its versatility and potential for widespread applicability in various laboratory automation contexts. By offering an open-source scheduling environment, our aim is to foster the development of accessible and adaptable laboratory automation solutions within the scientific community.