A crunch script is responsible for completing a single JobTask. In doing so, it will:
A task’s context is provided in environment variables.
||UUID of the current Job|
||UUID of the current JobTask|
||Hostname and port number of API server|
||Authentication token to use with API calls made by the current task|
The crunch script typically uses the Python SDK (or another suitable client library / SDK) to connect to the Arvados service and retrieve the rest of the details about the current job and task.
The Python SDK has some shortcuts for common operations.
In general, a crunch script can access information about the current job and task like this:
import arvados import os job = arvados.api().jobs().get(uuid=os.environ['JOB_UUID']).execute() $sys.stderr.write("script_parameters['foo'] == %s" % job['script_parameters']['foo']) task = arvados.api().job_tasks().get(uuid=os.environ['TASK_UUID']).execute() $sys.stderr.write("current task sequence number is %d" % task['sequence'])
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Code samples in this documentation are licensed under the Apache License, Version 2.0.