Cowthulhu
02/24/2024, 2:42 AMScout
02/24/2024, 2:42 AM@asset
decorator, and they can be thought of as software-defined representations of your data.
- Ops (formerly known as solids) are the functional units of computation in a Dagster pipeline. An op takes inputs, performs some computation or action, and produces outputs. Ops are the building blocks that you connect together to form a pipeline.
For your specific use case, here's how you might think about setting up a Dagster pipeline:
1. SFTP Resource: You would define a resource that handles the connection to the SFTP server. This resource would be responsible for fetching the file from the SFTP location.
2. Snowflake Resource: Similarly, you would define a resource for connecting to your Snowflake database. This resource would handle the credentials and connection logic required to insert data into Snowflake.
3. File to Snowflake Op: You would write an op that uses the SFTP resource to download the file and then uses the Snowflake resource to load the data into the database. This op would be the core computation step of your pipeline.
4. Assets: If you want to track the data as it moves through your pipeline, you could define assets for both the file from the SFTP server and the data in the Snowflake database. These assets would be updated each time the pipeline runs and would provide lineage and observability for your data.
Here's a very high-level example of what this might look like in code, based on the concepts from the documentation:
```python
from dagster import job, op, ResourceDefinition
# Define your SFTP resource
class SFTPClient:
def __init__(self, host, username, password):
# Initialize connection to SFTP
pass
def get_file(self, file_path):
# Logic to download file from SFTP
pass
sftp_resource = ResourceDefinition.hardcoded_resource(SFTPClient(...))
# Define your Snowflake resource
class SnowflakeConnector:
def __init__(self, user, password, account):
# Initialize connection to Snowflake
pass
def put_data(self, data):
# Logic to insert data into Snowflake
pass
snowflake_resource = ResourceDefinitioScout
02/24/2024, 2:42 AMCowthulhu
02/24/2024, 2:44 AMScout
02/24/2024, 2:44 AMpython from dagster import asset, op, ResourceDefinition, Out, Output # Resources definitions remain the same... # Define your op that uses both resources and produces an output @op(required_resource_keys={'sftp', 'snowflake'}, out=Out()) def file_to_snowflake(context): file_data = context.resources.sftp.get_file('/path/to/file') context.resources.snowflake.put_data(file_data) return file_data # Return the data as an output of the op # Define your asset that represents the data in Snowflake @asset def snowflake_data(context, file_data): # Here, you could perform additional transformations or simply pass the data through # You could also log metadata or perform checks <http://context.log.info|context.log.info>("Data loaded into Snowflake") return file_data # Define your job that ties everything together @job(resource_defs={'sftp': sftp_resource, 'snowflake': snowflake_resource}) def sftp_to_snowflake_job(): snowflake_data(file_to_snowflake())
In this example, the file_to_snowflake
op now returns the file data, which is then passed to the snowflake_data
asset. The asset function could be used to perform additional transformations or simply act as a pass-through. By defining the snowflake_data
asset, you create a software-defined representation of your data in Snowflake, which Dagster can track over time. This setup allows you to leverage Dagster's asset catalog, where you can see the history of updates to the snowflake_data
asset, dependencies between assets, and other metadata that you might log during the pipeline execution.Cowthulhu
02/24/2024, 2:48 AMScout
02/24/2024, 2:48 AMdeps
argument. This can simplify the process of defining how assets depend on one another, as opposed to managing dependencies through op inputs and outputs. 6. Graph-Backed Assets: In cases where an asset requires multiple computational steps, you might use a graph-backed asset. This allows you to define a series of ops (a graph) that computes the asset, while still tracking the asset as a single entity in Dagster. It's important to note that assets and ops are not mutually exclusive. You can use ops within assets to define the computation logic, and you can have assets that depend on other assets or ops. The choice between using an op or an asset for a particular piece of logic often comes down to whether you want to track the data as a long-lived object with lineage and observability features that assets provide.