Why is it that `@op`s cannot see resources like

@assets

can? For example, this works fine:

@asset(required_resource_keys={"snowflake"})
def my_thing(context: OpExecutionContext) -> None:
    return

but this does not work, even when right next to assets

@op(required_resource_keys={"snowflake"})
def my_thing(context: OpExecutionContext) -> None:
    return

and the error is

dagster._core.errors.DagsterInvalidDefinitionError: resource with key 'snowflake' required by op 'my_thing' was not provided. Please provide a <class 'dagster._core.definitions.resource_definition.ResourceDefinition'> to key 'snowflake', or change the required key to one of the following keys which points to an <class 'dagster._core.definitions.resource_definition.ResourceDefinition'>: ['io_manager']

I've understood it as an

@op

is not independently usable i.e. it needs to be utilized from a

@job

which in turn provide the resource definitions. Look at your Definition, the assets are included but ops are not. If assets aren't included in the Definition they wouldn't see the configured resources either.

That's not very clear with the examples in the documentation, but makes sense. So, I would to do something like:

@op(required_resource_keys={"snowflake"})
def my_thing(context: OpExecutionContext) -> None:
    return

@job(required_resource_keys={"snowflake"})
def my_job():
    my_thing()

and then @job will expose the resource to the @op?

You'd define the resources in the

@job

decorator similar to how you would supply them to a Definition, like this:

@op(required_resource_keys={"snowflake"})
def my_thing(context: OpExecutionContext) -> None:
    return

@job(resource_defs={"snowflake": snowflake_io_manager...})
def my_job():
    my_thing()

ah, ok. That seems kind of redundant, but works for me. 🙂

If you follow the full-featured example, it would be the "resource by stage" dict; you can re-use that resource block in

Definition()

or

@job()