https://dagster.io/ logo
#ask-ai
Title
# ask-ai
c

Caelan Schneider

03/07/2024, 4:02 PM
How do I define a nested configurable resource such that the inner resource can be reused by other resources without defining a new configuration?
s

Scout

03/07/2024, 4:02 PM
To define a nested configurable resource where the inner resource can be reused by other resources without defining a new configuration, you can follow the pattern described in the documentation for resources that depend on other resources. This involves defining the inner resource as a separate, nested resource and then using it as an attribute of the outer resource class. Here's a step-by-step guide based on the documentation: 1. Define the inner resource as a
ConfigurableResource
class. This class will manage its own configuration and can be reused by other resources. 2. Define the outer resource as another
ConfigurableResource
class. Within this class, you can include the inner resource as an attribute. 3. When configuring the outer resource, you provide an instance of the inner resource as an argument. This allows you to reuse the inner resource's configuration across multiple outer resources. Here's an example from the documentation, adapted to illustrate the concept:
Copy code
python from dagster import ConfigurableResource, Definitions, asset  # Define the inner resource class InnerResource(ConfigurableResource):     # Configuration schema and methods for the inner resource     ...  # Define the outer resource that depends on the inner resource class OuterResource(ConfigurableResource):     inner_resource: InnerResource      # The rest of the outer resource's implementation     ...  # Instantiate the inner resource with its configuration inner_resource_instance = InnerResource(...)  # Define the outer resource, reusing the inner resource instance outer_resource_instance = OuterResource(inner_resource=inner_resource_instance)  # Create definitions for Dagster to use defs = Definitions(     resources={         "outer_resource": outer_resource_instance,         # Other resources can also reuse `inner_resource_instance`     } )
In this example,
inner_resource_instance
is created once and can be passed to multiple outer resources. This allows you to define a shared configuration for the inner resource that can be reused without redefining it for each outer resource that depends on it. Remember that when you want to configure these resources at runtime, you can use the
configure_at_launch()
method for each resource that requires runtime configuration. This method allows you to provide configuration for the resource at launch time in the Launchpad or in Python code using the
config
parameter of the
RunRequest
. Keep in mind that the exact implementation details will depend on your specific use case and how you want to structure your resources and their dependencies. The provided example is a general pattern that you can adapt to fit your needs.
c

Caelan Schneider

03/07/2024, 4:04 PM
@Scout Can I put the inner resource in the definitions object and just have the outer resource reference that, instead of having the inner resource configured inside the outer resource?
s

Scout

03/07/2024, 4:04 PM
Yes, you can define the inner resource in the
Definitions
object and have the outer resource reference it. This approach allows you to define the inner resource once at the top level and then reference it in multiple outer resources without redefining its configuration each time. Here's how you can do it based on the documentation: 1. Define both the inner and outer resources as
ConfigurableResource
classes. 2. In the
Definitions
object, instantiate the inner resource with its configuration. 3. Reference the inner resource in the outer resource by including it as an attribute and providing it when you instantiate the outer resource in the
Definitions
object. Here's an example:
Copy code
python from dagster import ConfigurableResource, Definitions, asset  # Define the inner resource class InnerResource(ConfigurableResource):     # Configuration schema and methods for the inner resource     ...  # Define the outer resource that references the inner resource class OuterResource(ConfigurableResource):     inner_resource: InnerResource      # The rest of the outer resource's implementation     ...  # Instantiate the inner resource with its configuration inner_resource_instance = InnerResource(...)  # Define the Definitions object with the inner resource defs = Definitions(     resources={         "inner_resource": inner_resource_instance,     } )  # When you need to use the outer resource, reference the inner resource instance outer_resource_instance = OuterResource(inner_resource=defs.resources["inner_resource"])  # Add the outer resource to the Definitions object defs = Definitions(     resources={         "inner_resource": inner_resource_instance,         "outer_resource": outer_resource_instance,     } )
In this setup,
inner_resource_instance
is defined once in the
Definitions
object and can be referenced by any number of outer resources. This approach centralizes the configuration of the inner resource and makes it easy to manage and reuse across different parts of your Dagster project.
c

Caelan Schneider

03/07/2024, 7:40 PM
@Scout can I define a define a private resource dependency - i.e. not have to pass the inner resource as a paramater each time I instantiate the outer resource?
s

Scout

03/07/2024, 7:40 PM
As of my knowledge cutoff in early 2023, Dagster's
ConfigurableResource
system does not support private resource dependencies in the same way that traditional object-oriented programming might allow for private member variables. In Dagster, resources are designed to be explicitly passed around and referenced by their keys, which encourages clear and explicit dependency management. However, if you want to encapsulate the dependency such that users of the outer resource do not need to know about the inner resource, you could create a factory function or a method that constructs the outer resource with the inner resource already attached. This way, the users of the outer resource do not directly pass the inner resource; instead, they use the factory function or method that handles the instantiation internally. Here's an example of how you might define such a factory function:
Copy code
python from dagster import ConfigurableResource, Definitions  # Define the inner resource class InnerResource(ConfigurableResource):     # Configuration schema and methods for the inner resource     ...  # Define the outer resource that depends on the inner resource class OuterResource(ConfigurableResource):     inner_resource: InnerResource      # The rest of the outer resource's implementation     ...  # Define a factory function that creates an instance of the outer resource # with the inner resource already attached def create_outer_resource():     inner_resource_instance = InnerResource(...)     return OuterResource(inner_resource=inner_resource_instance)  # Use the factory function to create the outer resource instance outer_resource_instance = create_outer_resource()  # Define the Definitions object with the outer resource defs = Definitions(     resources={         "outer_resource": outer_resource_instance,     } )
In this example, the
create_outer_resource
function encapsulates the creation of the inner resource and the instantiation of the outer resource. Users of the outer resource simply call this function without needing to know about the inner resource's existence. Please note that while this approach can hide the instantiation details, it does not make the inner resource truly private in the sense that it cannot be accessed from outside the outer resource. If the inner resource is an attribute of the outer resource, it can still be accessed by anyone who has a reference to the outer resource instance. If there have been updates to Dagster's resource system that allow for private resource dependencies since my last update, I would recommend checking the latest Dagster documentation or reaching out to the Dagster community for the most current information.
15 Views