Lifecycle management with KedroSession

Note: This documentation is based on Kedro 0.17.1, if you spot anything that is incorrect then please create an issue or pull request.

Overview

A KedroSession allows you to:

  • Manage the lifecycle of a Kedro run

  • Persist runtime parameters with corresponding session IDs

  • Traceback runtime parameters, such as CLI command flags and environment variables

KedroSession decouples Kedro’s library components, managed by KedroContext, and any session data (both static and dynamic data). As a result, Kedro components and plugins can access session data without the need to import the KedroContext object and library components.

The main methods and properties of KedroSession are:

  • create(): Create a new instance of KedroSession with session data

  • load_context(): Instantiate KedroContext object

  • close(): Close the current session - we recommend that you use the session object as a context manager, which will call close() automatically, as opposed to calling the method explicitly

  • run(): Run the pipeline with the arguments provided. See the Running pipelines page for details

Create a session

KedroSession can be used as a context manager to construct a new KedroSession with session data provided. You should prefer to use the context manager because it automatically closes the session after the exit. The following code example creates KedroSession object as a context manager and runs a pipeline inside the context.

from kedro.framework.session import KedroSession

with KedroSession.create("<your-kedro-project-package-name>") as session:
    session.run()

You need to tell the KedroSession what is the package name of your Kedro project, so it can load your settings, nodes and pipelines. Additionally, you can provide the following optional arguments in KedroSession .create():

  • project_path: Path to the project root directory

  • save_on_close: A boolean value to indicate whether or not to save the session to disk when it’s closed

  • env: Environment for the KedroContext

  • extra_params: Optional dictionary containing extra project parameters for the underlying KedroContext. If you specify it, it will update (and therefore take precedence over) the parameters retrieved from the project configuration

When you want to access to the most recent session object, use a helper function get_current_session() as follows:

from kedro.framework.session import get_current_session

session = get_current_session()
context = session.load_context()
context.catalog.load("my_data").head()