How to make a greengrass component run only once?

1. Using Skipif with a File Marker (Your Approach)

After the component runs successfully, create a file or some sort of marker (e.g., a timestamp or flag) in the filesystem.

Use the Skipif lifecycle field in the recipe to check for the existence of this file and skip subsequent executions if it exists.

{
  "Lifecycle": {
    "Run": {
      "Script": "python3 /path/to/your/script.py",
      "Skipif": "[ -f /path/to/marker.file ]"
    }
  }
}

Pros: Simple and effective.

Cons: As you mentioned, this can feel a bit "hacky" since you're manually managing state

2. State Management within the Component Itself

Your component can maintain its own state and decide whether to execute the code or not. For example, after the first run, the component can write a status to a file or to a database. On subsequent runs, it checks the state and exits if it determines it should not run again.

import os

def main():
    if os.path.exists("/path/to/marker.file"):
        print("Component has already run, exiting.")
        return
    # Run the component logic here
    print("Running the component...")
    # After successful run, create the marker file
    with open("/path/to/marker.file", "w") as f:
        f.write("done")

if __name__ == "__main__":
    main()

Pros: Keeps the logic self-contained within the component.

Cons: You are still manually managing state, but within the component itself.

3. Leverage Greengrass Component Versioning

Greengrass allows versioning of components. You could design the component in such a way that it only runs once per version. After a deployment, it would not run again unless a new version of the component is deployed.

You can combine this with the Skipif approach but tie it to a specific version of the component.

{
  "Lifecycle": {
    "Run": {
      "Script": "python3 /path/to/your/script.py",
      "Skipif": "[ -f /path/to/marker-for-version-1.0.0.file ]"
    }
  }
}

4. Using the Greengrass Deployment API (Advanced Approach)

You can potentially use AWS IoT Greengrass deployment lifecycle events and build a custom handler to manage one-shot behavior programmatically. This could involve monitoring deployment states and triggering a custom script only during initial deployments.

Pros: More flexible and can be integrated with other custom deployment lifecycle actions.

Cons: Requires more setup and deeper integration with the AWS SDK and Greengrass APIs.