Introducing Shepherd: Simplifying Integration of Service Workflows into Task-Based Workflows

We are pleased to announce the release of Shepherd, an open-source tool designed to streamline the integration of service workflows into task-based workflows. Shepherd enables users to manage applications that require dynamic dependencies and state monitoring, ensuring that each component in a workflow starts only after its dependencies have reached specified states.

What Is Shepherd?

Shepherd is a local workflow manager and service orchestrator that launches and monitors applications according to a user-defined configuration. It bridges the gap between persistent services and traditional task-based workflows by treating services as first-class tasks. This approach allows for seamless integration of services that run indefinitely or until explicitly stopped, alongside actions that run to completion.

By analyzing log outputs and file contents, Shepherd tracks the internal states of tasks without the need to modify their original code. This capability is particularly useful when integrating persistent services into workflows where tasks may depend on the internal states of these services rather than their completion.

Key Features

• Services as Tasks: Treats both actions (tasks that run to completion) and services (persistent tasks that require explicit termination) as tasks within a workflow, allowing integration into task-based workflow managers.
• Dynamic Dependency Management: Initiates tasks based on the internal states of other tasks, enabling complex state-based dependencies. Supports both "any" and "all" dependency modes for flexible configurations.
• State Monitoring: Continuously monitors the internal state of each task by analyzing standard output and specified files, updating states in real-time based on user-defined patterns.
• Graceful Startup and Shutdown: Ensures tasks start only when their dependencies are met and provides controlled shutdown mechanisms to maintain system stability and prevent data loss.
• Logging and Visualization: Generates comprehensive logs and state transition data, aiding in performance analysis and debugging.
• Integration with Larger Workflows: By encapsulating service workflows into single tasks, Shepherd enables integration with larger distributed workflow managers, enhancing workflow flexibility and reliability.

Documentation and Source Code

For detailed documentation, examples, and source code, please visit the Shepherd GitHub Repository.