Workflow Versioning and Backward Compatibility: Stop Breaking Long-Running Executions

Workflow versioning in production systems is a critical aspect of maintaining correctness, especially given the time dimension in long-running orchestration processes. Workflow definitions can evolve while executions are still ongoing, posing challenges in contract evolution and asynchronous execution. This complexity is illustrated through a loan origination workflow where new versions can affect the execution of older applications, potentially leading to failures if proper version mapping is not implemented. The open-source Orkes Conductor engine addresses these challenges by making behavior explicit, ensuring that workflows start deterministically, with explicit execution continuity, and maintaining worker compatibility across different payload schemas. Through a detailed walkthrough, the text demonstrates how to implement and verify workflow versioning safely using Conductor, highlighting the importance of backward compatibility, explicit migration policies, and controlled upgrade processes. The guide ultimately underscores the need for teams to view workflow versioning as a runtime systems problem, allowing for proactive failure management and migration safety assurance through executable checks, rather than relying solely on documentation.