The reference graph processed every work unit inside a single op, so exactly one worker was ever reported regardless of executor. That made the guide's claim that k8s_job_executor yields several distinct contributing_hosts false, and left the reference implementations unable to demonstrate the executor choice at all. generate_work_units is now a DynamicOut and both graphs map over it, so one step is created per unit and the loosely coupled pattern dispatches one external workload per unit. Evidence is split into contributing_workers (host and pid, differs per process) and contributing_hosts (differs only across machines), because the previous single field could not distinguish multiprocess fan-out from no fan-out. Tests now assert the mapped step keys rather than a host count, since execute_in_process ignores executor_def and cannot prove executor behaviour on its own. Adds a Windows note: multiprocess_executor did not complete during authoring and left orphaned processes. Changelog: fixed
60 lines
1.9 KiB
Python
60 lines
1.9 KiB
Python
"""External payload for the loosely coupled execution target.
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This script is deliberately NOT a Dagster code location. It depends only on
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``dagster-pipes``, never on ``dagster``, and it never opens a connection to the
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orchestration metadata database. Everything it reports reaches the control plane
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through the pipes message channel.
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Run by ``distributed_execution.loosely_coupled.jobs`` via either
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``PipesSubprocessClient`` (local) or ``PipesK8sClient`` (cluster).
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"""
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import os
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import socket
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from dagster_pipes import open_dagster_pipes
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# Presence of any of these would mean the payload was granted orchestration
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# runtime credentials it has no business holding.
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ORCHESTRATION_ENV_VARS = (
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"DAGSTER_POSTGRES_HOST",
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"DAGSTER_POSTGRES_USER",
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"DAGSTER_POSTGRES_DB",
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)
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def main() -> None:
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with open_dagster_pipes() as pipes:
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units = pipes.get_extra("units")
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host = socket.gethostname()
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worker = f"{host}#{os.getpid()}"
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pipes.log.info(f"External payload started on {worker} with {len(units)} work units")
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results = [
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{"unit": unit, "squared": unit * unit, "host": host, "worker": worker} for unit in units
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]
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leaked = [name for name in ORCHESTRATION_ENV_VARS if os.environ.get(name)]
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if leaked:
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pipes.log.warning(
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"Orchestration runtime credentials are visible to this payload: "
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f"{', '.join(leaked)}. A loosely coupled target should not have them."
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)
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# The only channel back to the control plane.
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pipes.report_custom_message(
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{
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"results": results,
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"host": host,
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"worker": worker,
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"orchestration_env_visible": leaked,
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}
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)
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pipes.log.info(f"External payload finished on {worker}")
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if __name__ == "__main__":
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main()
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