Jacob Marcil
02/08/2024, 3:07 PMScout
02/08/2024, 3:07 PMrun_config
to specify the necessary parameters such as database credentials, API keys, or any other required configuration.
5. Execution: Execute the pipeline, ensuring that the solid that makes the API call is invoked for each row fetched by the database query solid.
Here's a high-level example of what the code might look like, based on the concepts from the documentation:
python
from dagster import pipeline, solid, execute_pipeline, resource
# Define a resource for the database connection
@resource
def db_connection(context):
# Code to establish database connection
pass
# Define a resource for the API client
@resource
def api_client(context):
# Code to create an API client
pass
# Define a solid to query the database
@solid(required_resource_keys={'db_connection'})
def query_database(context):
# Use the db_connection resource to fetch rows from the database
rows = context.resources.db_connection.fetch_rows()
return rows
# Define a solid to call the API for each row
@solid(required_resource_keys={'api_client'})
def call_api_for_row(context, row):
# Use the api_client resource to make the API call for the given row
response = context.resources.api_client.call_api(row)
return response
# Construct the pipeline
@pipeline(mode_defs=[ModeDefinition(resource_defs={'db_connection': db_connection, 'api_client': api_client})])
def my_pipeline():
rows = query_database()
responses = call_api_for_row.map(rows)
# Execute the pipeline
if __name__ == "__main__":
result = execute_pipeline(my_pipeline, run_config={
'resources': {
'db_connection': {'config': {'connection_string': '...'}},
'api_client': {'config': {'api_key': '...'}}
}
})
Please note that this isScout
02/08/2024, 3:09 PMJacob Marcil
02/08/2024, 3:10 PMScout
02/08/2024, 3:10 PMrun_config
.
5. Execution: Run the pipeline, which will execute the solid that makes the API call for each row fetched from the database.
Here's a conceptual example based on the Dagster API:
```python
from dagster import pipeline, solid, execute_pipeline, resource, ModeDefinition
# Define a resource for the database connection
@resource
def db_connection(context):
# Code to establish database connection
pass
# Define a resource for the API client
@resource
def api_client(context):
# Code to create an API client
pass
# Define a solid to query the database
@solid(required_resource_keys={'db_connection'})
def query_database(context):
# Use the db_connection resource to fetch rows from the database
rows = context.resources.db_connection.fetch_rows()
return rows
# Define a solid to call the API for each row
@solid(required_resource_keys={'api_client'})
def call_api_for_row(context, row):
# Use the api_client resource to make the API call for the given row
response = context.resources.api_client.call_api(row)
return response
# Construct the pipeline
@pipeline(mode_defs=[ModeDefinition(resource_defs={'db_connection': db_connection, 'api_client': api_client})])
def my_pipeline():
rows = query_database()
for row in rows:
call_api_for_row(row)
# Execute the pipeline
if name == "__main__":
result = execute_pipeline(my_pipeline, run_config={
'resources': {
'db_connection': {'config': {'connection_string': '...'}},
'api_client': {'config': {'api_Scout
02/08/2024, 3:11 PMdb_connection.fetch_rows()
and api_client.call_api(row)
based on your actual database and API. Please refer to the latest Dagster documentation for any updates or changes in the API that might affect how you implement such a pipeline in Dagster 1.6 or later versions.Jacob Marcil
02/08/2024, 3:35 PMScout
02/08/2024, 3:36 PMrun_config
.
5. Execution: Run the job, which will execute the op that makes the API call for each row fetched from the database.
Here's a conceptual example using the updated terminology:
python
from dagster import job, op, resource
# Define a resource for the database connection
@resource
def db_connection(context):
# Code to establish database connection
pass
# Define a resource for the API client
@resource
def api_client(context):
# Code to create an API client
pass
# Define an op to query the database
@op(required_resource_keys={'db_connection'})
def query_database(context):
# Use the db_connection resource to fetch rows from the database
rows = context.resources.db_connection.fetch_rows()
return rows
# Define an op to call the API for each row
@op(required_resource_keys={'api_client'})
def call_api_for_row(context, row):
# Use the api_client resource to make the API call for the given row
response = context.resources.api_client.call_api(row)
return response
# Construct the job
@job(resource_defs={'db_connection': db_connection, 'api_client': api_client})
def my_job():
rows = query_database()
for row in rows:
call_api_for_row(row)
# Execute the job
if __name__ == "__main__":
result = my_job.execute_in_process(run_config={
'resources': {
'db_connection': {'config': {'connection_string': '...'}},
'api_client': {'config': {'api_key': '...'}}
}
})
Please note that this is a high-level example and does not include the actual implementation details for database querying or API calling, which would be specific to your database and API. You would need to fill in the logic for db_connection.fetch_rows()
and api_client.call_api(row)
based on your actual database and API.
Remember to check the latest Dagster documentation for any updatScout
02/08/2024, 3:37 PMJacob Marcil
02/08/2024, 3:40 PMScout
02/08/2024, 3:40 PMpython
from dagster import IOManager, io_manager, op, Out, Output, job, resource
class MyIOManager(IOManager):
def handle_output(self, context, obj):
# Implement logic to store the object (the API response)
# For example, write to a file or a database
pass
def load_input(self, context):
# Implement logic to load inputs if necessary
pass
@io_manager
def my_io_manager(_):
return MyIOManager()
# Define a resource for the API client
@resource
def api_client(context):
# Code to create an API client
pass
# Define an op to call the API for each row and store the result
@op(required_resource_keys={'api_client'}, out=Out(io_manager_key="my_io_manager"))
def call_api_for_row(context, row):
try:
# Use the api_client resource to make the API call for the given row
response = context.resources.api_client.call_api(row)
# Return the response as an output to be handled by the IOManager
return Output(response)
except Exception as e:
context.log.error(f"API call for row {row} failed with exception: {e}")
# Do not return an output for failed API calls
# Construct the job with the custom IOManager attached to the op's output
@job(resource_defs={'api_client': api_client, 'my_io_manager': my_io_manager})
def my_job():
# Assume `query_database` is an op that retrieves rows from a database
rows = query_database()
for row in rows:
call_api_for_row(row)
# Execute the job
if __name__ == "__main__":
result = my_job.execute_in_process(run_config={
'resources': {
'api_client': {'config': {'api_key': '...'}}
}
})
In this example, MyIOManager
is a custom IOManager that you would need to implement with the logic for storing the API responses. The call_api_for_row
op is designed to handle exceptions and only produce an output if the API call is successful. The successful responses are then passed to theScout
02/08/2024, 3:41 PMOutput
object. Remember to implement the handle_output
method in MyIOManager
with the appropriate logic for storing the data in your desired format and location. You can also implement the load_input
method if you need to retrieve data for inputs, but it's not necessary if you're only storing outputs. Please refer to the latest Dagster documentation for more details on implementing IOManagers and handling op outputs.Jacob Marcil
02/08/2024, 3:43 PMScout
02/08/2024, 3:43 PMpython
from dagster import IOManager, io_manager, op, Out, Output, graph, AssetMaterialization, asset
from dagster.core.definitions.decorators.graph import graph_asset
class MyIOManager(IOManager):
def handle_output(self, context, obj):
# Implement logic to store the object (the API response)
# For example, write to a file or a database
pass
def load_input(self, context):
# Implement logic to load inputs if necessary
pass
@io_manager
def my_io_manager(_):
return MyIOManager()
# Define a resource for the API client
@resource
def api_client(context):
# Code to create an API client
pass
# Define an op to call the API for each row
@op(required_resource_keys={'api_client'}, out=Out(io_manager_key="my_io_manager"))
def call_api_for_row(context, row):
try:
# Use the api_client resource to make the API call for the given row
response = context.resources.api_client.call_api(row)
# Return the response as an output to be handled by the IOManager
return Output(response)
except Exception as e:
context.log.error(f"API call for row {row} failed with exception: {e}")
# Do not return an output for failed API calls
# Define a graph that encapsulates the logic
@graph
def my_graph(rows):
for row in rows:
call_api_for_row(row)
# Create a graph-backed asset
@graph_asset
def my_asset():
# Assume `query_database` is an op that retrieves rows from a database
rows = query_database()
my_graph(rows)
# Execute the job
if __name__ == "__main__":
result = my_asset.execute_in_process(run_config={
'resources': {
'api_client': {'config': {'api_key': '...'}}
}
})
In this example, my_graph
is a graph that includes the logic for making API calls for each row. The my_asset
function is decorated with @graph_asset
, which creates a graph-backed asset from the my_graph
grapScout
02/08/2024, 3:44 PMmy_io_manager
is used to handle the storage of successful API responses. When you execute the my_asset
, it will run the graph and store the successful API responses using the MyIOManager
. The AssetMaterialization
event can be used to log materializations in Dagit, Dagster's UI, but it's not shown in this example. Please refer to the latest Dagster documentation for more details on implementing graph-backed assets and IOManagers.Jacob Marcil
02/08/2024, 3:47 PMScout
02/08/2024, 3:47 PMcall_api_for_row
ops fail due to an exception, the following would happen: 1. The exception is caught by the try-except
block within the call_api_for_row
op. 2. An error message is logged using context.log.error
, indicating that the API call for the specific row failed. 3. The op does not yield an Output
object for that particular row because the return Output(response)
line is inside the try
block and will be skipped in case of an exception. 4. The IOManager's handle_output
method will not be called for that failed op, as there is no output to handle. 5. The pipeline will continue executing the remaining ops for other rows. The failure of one op does not stop the execution of subsequent ops unless you have configured the pipeline to behave differently upon encountering an error. The result is that only successful API call responses are stored by the IOManager, and any failed calls are logged and skipped without causing the entire job to fail. This behavior allows the job to be resilient to individual failures, which is often desirable when dealing with external API calls that may occasionally fail due to transient issues. Remember that this behavior is based on the specific error handling logic you implement within your ops. If you want to change how failures are handled (for example, to retry failed calls or to halt the entire job), you would need to adjust the error handling code accordingly.Jacob Marcil
02/08/2024, 5:02 PMScout
02/08/2024, 5:02 PMpython
from dagster import sensor, RunRequest, job, op, repository
# Define an op that performs the API call for a given row
@op
def process_row(row):
# Code to perform the API call
# If the API call fails, the op will fail, and the run will fail
pass
# Define a job that processes a single row
@job
def process_single_row():
process_row()
# Define a sensor that triggers a run for each row in the database
@sensor(job=process_single_row)
def row_processing_sensor(context):
# Code to query the database and get rows that need processing
rows_to_process = get_rows_to_process()
for row in rows_to_process:
# Create a run request for each row
yield RunRequest(
run_key=f"row-{row.id}", # Unique identifier for the run
run_config={
"ops": {
"process_row": {
"inputs": {
"row": row,
}
}
}
},
)
# Define a repository to hold the job and sensor
@repository
def my_repository():
return [process_single_row, row_processing_sensor]
def get_rows_to_process():
# Placeholder function to fetch rows from the database
# Replace with actual database query logic
return [{"id": 1, "data": "row1"}, {"id": 2, "data": "row2"}]
In this example, row_processing_sensor
is a sensor that checks for rows that need to be processed. For each row, it creates a RunRequest
that triggers a new run of the process_single_row
job with the specific row data as input.
Please note tScout
02/08/2024, 5:03 PMget_rows_to_process()
and process_row
based on your actual database and API. Keep in mind that this approach may result in a large number of runs if there are many rows to process, which could have implications for system performance and resource utilization. It's important to consider the scalability of this solution and whether it fits your use case and infrastructure.Jacob Marcil
02/08/2024, 6:01 PMScout
02/08/2024, 6:01 PMScout
02/08/2024, 6:03 PMdaily_api_calls_job
job is scheduled to run every day at noon UTC. The query_database
op fetches rows from the database, and the call_api_and_store
op makes the API call and stores the result. If an API call fails, an alert is sent, and the op is retried up to three times. Please note that this is a high-level example and does not include the actual implementation details for the database querying, API calling, result storing, or alerting logic. You would need to fill in the logic for the resource implementations and ops based on your actual database, API, and alerting system. To manually retry failed jobs, you can use Dagster's Dagit UI to view failed runs and trigger retries. You can also configure alerts to notify you when a run fails, allowing you to take action as needed.