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pyproject.toml settings

note

This article assumes you have already created a project with components.

pyproject.toml contains tool.dagster and tool.dg sections:

jaffle-platform/pyproject.toml
...
[tool.dagster]
module_name = "jaffle_platform.definitions"
code_location_name = "jaffle-platform"

[tool.dg]
is_project = true
...

tool.dagster section​

The tool.dagster section of pyproject.toml is not dg-specific. This section specifies that a set of definitions can be loaded from the jaffle_platform.definitions module.

tool.dg section​

The tool.dg section contains is_project and is_component_lib settings.

is_project setting​

is_project = true specifies that this project is a dg-managed Dagster project. Projects created with components are regular Dagster projects with a particular structure.

To understand the structure, let's look at the content of jaffle_platform/definitions.py:

jaffle-platform/jaffle_platform/definitions.py
from pathlib import Path

from dagster_components import build_component_defs

defs = build_component_defs(components_root=Path(__file__).parent / "components")

This call to build_component_defs will:

  • discover the set of components defined in the project
  • compute a set of Definitions from each component
  • merge the component-specific definitions into a single Definitions object

is_project is telling dg that the project is structured in this way and therefore contains component instances. In the current project, component instances will be placed in the default location at jaffle_platform/components.

is_component_lib setting​

is_component_lib = true specifies that the project is a component library. This means that the project may contain component types that can be referenced when generating component instances.

In a typical project, most components are likely to be instances of types defined in external libraries (e.g. dagster-components), but you can also define custom component types scoped to your project. That is why is_component_lib is set to true by default. Any scaffolded component types in jaffle_platform will be placed in the default location at jaffle_platform/lib.

You can also see that this module is registered under the dagster.components entry point in pyproject.toml. This is what makes the components discoverable to dg:

jaffle-platform/pyproject.toml
...
[project.entry-points]
"dagster.components" = { jaffle_platform = "jaffle_platform.lib"}
...