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Dagster Pipes#

Dagster Pipes is a toolkit for building integrations between Dagster and external execution environments. It standardizes the process of passing parameters, injecting context information, ingesting logs, and collecting metadata all while remaining agnostic to how remote computations are launched in those environments. This enables the separation of orchestration and business logic in the Dagster ecosystem.

It is particularly useful for the process of incorporating pre-existing code, business logic, and execution environments into Dagster. With Dagster Pipes and a few lines of code, you can execute your code through the orchestrator. In turn, you can stream logs and metadata back to Dagster so you can leverage its observability, lineage, cataloging, and debugging capabilities.

Benefits#

With Dagster Pipes, you can:

  • Incorporate existing code into Dagster without huge refactors
  • Onboard stakeholder teams onto Dagster incrementally
  • Run code in external environments, and:
    • Easily pass parameters to the code
    • Stream logs and structured messages back to Dagster
  • Separate orchestration and business logic environments
  • Use languages other than Python with Dagster

How it works#

Dagster Pipes provides a protocol between the orchestration environment (Dagster) and external execution (ex: Databricks), and a toolkit for building implementations of that protocol.

When Dagster Pipes is invoked, several steps will be carried out in Dagster's orchestration process and in the external process, such as Databricks.

In the orchestration process (Dagster)#

When Dagster Pipes is called in a Dagster asset or op, Dagster launches the external process with parameters and context information (ex: partition_key, asset_key, etc.)

Diagram explaining the Dagster Pipes process

In the external process#

The process starts and loads the context info provided by Dagster. While the process runs, execution data, logs, and any specified metadata are streamed back to Dagster.

After Dagster receives the data from the external process, it’ll be visible in the Dagster UI.

Limitations#

While Dagster Pipes is lightweight and flexible, there are a few limitations to be aware of:

  • Step launchers and Pipes can't currently be used together. Dagster Pipes is a lightweight alternative to step launchers. Think of this as an either-or situation - you can use step launchers or you can use Dagster Pipes. If your external code requires the core Dagster module (see below), you should use step launchers instead of Pipes.

  • Some Dagster concepts aren't supported for use in external processes. Dagster Pipes (dagster-pipes) doesn't include the core Dagster (dagster) library. As such, concepts like resources and I/O managers, which are included in dagster, aren't available for use in external processes executed by Dagster Pipes.

    For example, I/O managers aren't currently supported. A work-around is demonstrated in the step launchers migration guide.

Usage#

Ready to get started with Dagster Pipes? Depending on what your goal is, how you approach using Dagster Pipes can differ.