Brett
03/01/2024, 2:48 AMScout
03/01/2024, 2:48 AMBrett
03/01/2024, 2:58 AMScout
03/01/2024, 2:58 AMmy_dagster_project/ │ ├── dagster.yaml # Dagster instance configuration │ ├── workspace.yaml # Workspace configuration │ └── my_pipeline/ ├── __init__.py ├── jobs.py # Where jobs are defined └── ops.py # Where ops are defined
In this structure, my_pipeline
is a directory that contains your Dagster job and ops definitions. The jobs.py
file is where you define your job, and the ops.py
file is where you define your ops. Example of an Ops Job (jobs.py
): python from dagster import job from my_pipeline.ops import fetch_data, process_data, store_data @job def my_data_processing_job(): raw_data = fetch_data() processed_data = process_data(raw_data) store_data(processed_data)
Example Ops Definitions (ops.py
): python from dagster import op @op def fetch_data(): # Logic to fetch data from a source return {"data": "raw data"} @op def process_data(input_data): # Logic to process the fetched data processed = f"processed {input_data['data']}" return {"data": processed} @op def store_data(processed_data): # Logic to store the processed data print(f"Storing data: {processed_data['data']}")
In this example, my_data_processing_job
is an ops job that consists of three ops: fetch_data
, process_data
, and store_data
. Each op represents a step in the data processing workflow. The @job
decorator is used to define the job, and within the job definition, the ops are called in a sequence that respects their data dependencies. To run this job, you would execute it through the Dagster CLI, the Dagster UI, or programmatically using the Python API. The project structure and job definition help maintain organization and clarity as your Dagster project grows.Brett
03/01/2024, 3:01 AMScout
03/01/2024, 3:01 AMdagster.yaml
file is used to configure your Dagster instance, including settings for storage, run launchers, sensors, and schedules. It's typically located in the DAGSTER_HOME
directory, which is an environment variable that points to a directory on your filesystem where Dagster stores instance-level configuration and history. An example dagster.yaml
might look like this: yaml # dagster.yaml run_storage: module: dagster_postgres.run_storage class: PostgresRunStorage config: postgres_db: username: ... password: ... hostname: ... db_name: ... event_log_storage: module: dagster_postgres.event_log class: PostgresEventLogStorage config: postgres_db: username: ... password: ... hostname: ... db_name: ... schedule_storage: module: dagster_postgres.schedule_storage class: PostgresScheduleStorage config: postgres_db: username: ... password: ... hostname: ... db_name: ... scheduler: module: dagster.core.scheduler class: DagsterDaemonScheduler
The workspace.yaml
file defines code locations for local development or deploying to your infrastructure. It tells Dagster where to find the code that defines your pipelines, jobs, and other components. An example workspace.yaml
for the project structure provided earlier might look like this: yaml # workspace.yaml load_from: - python_file: relative_path: my_pipeline/jobs.py
In this workspace.yaml
file, we specify that we want to load our job definitions from the jobs.py
file located in the my_pipeline
directory relative to the location of the workspace.yaml
file. When you run Dagster tools like dagit
(the Dagster UI) or the Dagster CLI, they will use this file to locate and load your job definitions. Please note that the actual content of these files will depend on your specific setup, including what database you're using for storage, what kind of run launcher you have, and other instance-level settings. The examples above are just templates to give you an idea of what these files might contain.Brett
03/01/2024, 3:08 AMScout
03/01/2024, 3:08 AMdagster.yaml
with all possible configurable options would be quite extensive and potentially overwhelming, as there are many options that can be configured based on the specific needs of your Dagster instance. These options include configurations for run storage, event log storage, compute log storage, schedule storage, run launchers, executors, and more. However, I can guide you to the Dagster documentation, which provides a comprehensive reference for the dagster.yaml
file. The documentation includes detailed descriptions of all the configurable components and their respective options. It's important to tailor the dagster.yaml
file to your deployment's specific requirements, such as the choice of databases, object stores, and other infrastructure components. Here's a simplified example of what a dagster.yaml
might include, with placeholders for you to fill in based on your infrastructure: yaml # dagster.yaml run_storage: module: dagster_postgres.run_storage class: PostgresRunStorage config: postgres_db: username: "your_username" password: "your_password" hostname: "your_host" db_name: "your_db_name" event_log_storage: module: dagster_postgres.event_log class: PostgresEventLogStorage config: postgres_db: username: "your_username" password: "your_password" hostname: "your_host" db_name: "your_db_name" compute_log_manager: module: dagster.core.storage.local_compute_log_manager class: LocalComputeLogManager config: base_dir: "/path/to/compute/logs" schedule_storage: module: dagster_postgres.schedule_storage class: PostgresScheduleStorage config: postgres_db: username: "your_username" password: "your_password" hostname: "your_host" db_name: "your_db_name" scheduler: module: dagster.core.scheduler class: DagsterDaemonScheduler run_launcher: module: dagster.core.launcher class: DefaultRunLauncher telemetry: enabled: false execution: multiprocess: config: max_concurrent: 4 resources: io_manager: config: s3_bucket: "your_bucket_name" s3_prefix: "your_prefix"
This example includes configurations for PostgreSQL-backed run storage, event log storage, and schedule storage, a local compute log manager, the default run launcher, and a multiprocess executor with a maximum of four concurrent processes. It also includes a placeholder for an S3-backed IO manager. Please refer to the Dagster documentation for a full list of configurable options and detailed explanations of each component. The exact configuration will depend on the components you use and the infrastructure you deploy to.Brett
03/01/2024, 3:13 AMfrom dagster import job, op
@op
def return_five():
return 5
@op
def add_one(arg):
return arg + 1
@job
def do_stuff():
add_one(return_five())
What else do i have to do for it to show up in the dagster ui @ScoutScout
03/01/2024, 3:13 AMworkspace.yaml
file that tells Dagster where to find your job definitions. This file should be in the Dagster home directory or in the root of your project. Here's an example workspace.yaml
that points to a Python file: yaml load_from: - python_file: relative_path: "path_to_your_python_file.py" location_name: "my_location"
Replace "path_to_your_python_file.py"
with the actual path to your Python file containing the job definition. 2. Dagster Instance Configuration: Ensure you have a dagster.yaml
file that configures your Dagster instance. This file typically resides in the DAGSTER_HOME
directory. If you haven't set DAGSTER_HOME
, it defaults to $HOME/.dagster
. 3. Start Dagit (Dagster UI): Run Dagit, which is the web interface for Dagster. You can start it by running the following command in your terminal: shell dagit -f path_to_your_python_file.py
Or if you have a `workspace.yaml`: shell dagit
Make sure you are in the directory that contains your workspace.yaml
when you run this command. 4. Access Dagit: Once Dagit is running, it will provide you with a local URL, usually <http://localhost:3000>
. Open this URL in your web browser to access the Dagster UI. 5. View and Launch Job: In the Dagster UI, navigate to the "Jobs" section. You should see your do_stuff
job listed there. You can click on it and then click "Launch Run" to execute the job. If you've done all of the above and the job still doesn't show up or run, check for the following common issues: - Make sure there are no syntax errors or exceptions in your Python file. - Ensure that the Python environment where Dagit is running has Dagster and any other necessary dependencies installed. - Check the terminal where you started Dagit for any error messages. - Ensure that the workspace.yaml
file is correctly formatted and points to the right location of your job definition file. If you continue to face issues, you may want to check the Dagster documentation or community resources for troubleshooting tips or consider reaching out to the Dagster community for support.Brett
03/01/2024, 3:31 AMScout
03/01/2024, 3:31 AMprocess_data
and you only want to run this op, you would use the following op selection syntax in the configuration editor: yaml ops: process_data: {}
If you want to run process_data
and all of its downstream dependencies, you would use: yaml ops: process_data: "*"
5. Launch the Run: After specifying the op selection in the configuration, click the "Launch Run" button to execute only the selected op(s). Keep in mind that the op selection feature is designed to run the selected op along with its necessary dependencies unless you explicitly use the wildcard syntax to include downstream ops. The exact syntax for op selection may vary depending on the version of Dagster you are using, so it's a good idea to refer to the latest Dagster documentation for the most accurate and up-to-date information.Brett
03/01/2024, 3:43 AMfrom dagster import job, op
@op
def return_five():
return 5
@op
def add_one(arg):
return arg + 1
@job
def do_stuff():
add_one(return_five())
@ScoutScout
03/01/2024, 3:43 AMadd_one
) in your job from the Dagster UI's Launchpad, you would need to use the op selection feature. However, since add_one
depends on the output of return_five
, you cannot run add_one
in isolation without first running return_five
to provide the necessary input. In Dagster, ops (tasks) are designed to run as part of a directed acyclic graph (DAG), where the output of one op is passed as input to another. This means that if an op has dependencies, those dependencies must be executed to provide the context and inputs required for the op to run. If you still want to test or run the add_one
op separately, you would need to provide a way for it to receive the input it expects without having to execute return_five
. One approach to achieve this is to refactor your job to allow for more flexible execution paths or to provide hardcoded inputs for testing purposes. However, as of my knowledge cutoff date in early 2023, Dagster does not support executing a single op in the middle of a job's execution graph without running its upstream dependencies. The op selection syntax allows you to select a subset of the graph to run, but it will always include the necessary upstream ops to satisfy the dependencies of the selected ops. For testing individual ops in isolation, you can use the execute_in_process
method on the job definition, which allows you to specify inputs for each op directly in your test code. This method is typically used for unit testing and debugging purposes. Here's an example of how you might test the add_one
op in isolation: python result = do_stuff.execute_in_process( inputs={"return_five": 5} ) assert result.success assert result.output_for_node("add_one") == 6
In this example, we're providing a hardcoded input for the return_five
op when calling execute_in_process
, which allows us to effectively test the add_one
op in isolation.Brett
03/01/2024, 3:53 AMScout
03/01/2024, 3:53 AMadd_one
op from the Dagster UI: 1. Complete Initial Run: First, you need to have a successful run of the entire job so that all outputs are stored and available for downstream ops. 2. Navigate to the Runs Page: Go to the "Runs" section in the Dagster UI and find the run you want to re-execute. 3. Select the Run for Re-execution: Click on the run to view its details. 4. Choose Re-execution Option: In the run's detail view, you should see options for re-execution. Click on the "Re-execute" button, which may present you with different re-execution strategies. 5. Select Specific Op: Choose the option that allows you to re-execute from a specific op or step. You can then select the add_one
op for re-execution. 6. Launch Re-execution: After selecting the op, launch the re-execution. Dagster will use the outputs from the previous run as inputs to the add_one
op, effectively isolating and running only that op. This feature is particularly useful when you have a long-running job and one of the later ops fails; you can fix the issue and re-execute from the point of failure without having to run the entire job again. Please note that the exact UI elements and steps may vary depending on the version of Dagster you are using. Always refer to the latest Dagster documentation or UI tooltips for the most accurate guidance.