# Context


This module implements the Prefect context that is available when tasks run.

Tasks can import prefect and access prefect.context values that will be set when the task is run.

Context values can be accessed as attributes or as dictionary items.

Mutating the context from within a task is not recommended as it will not behave consistently across execution environments. Example:

import prefect

with prefect.context(dict(a=1, b=2)):
    print(prefect.context.a) # 1

print(prefect.context.get("a")) # undefined

Prefect provides various key / value pairs in context that are always available during task runs:

Variable Description
date an actual datetime object representing the current time
today the current date formatted as YYYY-MM-DD
today_nodash the current date formatted as YYYYMMDD
yesterday yesterday's date formatted as YYYY-MM-DD
yesterday_nodash yesterday's date formatted as YYYYMMDD
tomorrow tomorrow's date formatted as YYYY-MM-DD
tomorrow_nodash tomorrow's date formatted as YYYYMMDD
logger the logger for the current task
config the complete Prefect configuration object that is being used during this run
flow_name the name of the current flow
scheduled_start_time a datetime object representing the scheduled start time for the flow run; falls back to now for unscheduled runs
parameters a dictionary of parameter values for the current flow run
map_index the map index of the current task (if mapped, otherwise None)
task_name the name of the current task
task_full_name the name of the current task, including map index
task_slug the slug of the current task
task_tags the tags on the current task
task_run_count the run count of the task run - typically only interesting for retrying tasks
task_loop_count if the Task utilizes looping, the loop count of the task run
task_run_name the run name of the current task (if provided, otherwise None)
task_loop_result if the Task is looping, the current loop result

Prefect Cloud and Server supply some additional context variables:

Variable Description
flow_id the id of the current flow
flow_run_id the id of the current flow run
flow_run_version the state version of the current flow run
flow_run_name the name of the current flow run
task_id the id of the current task
task_run_id the id of the current task run
task_run_version the state version of the current task run
resume boolean showing if the current task run was manually restarted

Users can also provide values to context at runtime. For more information, see the Context concept doc.

# Context

class

prefect.utilities.context.Context

(*args, **kwargs)[source]

A thread safe context store for Prefect data.

The Context is a DotDict subclass, and can be instantiated the same way.

Args:

  • *args (Any): arguments to provide to the DotDict constructor (e.g., an initial dictionary)
  • **kwargs (Any): any key / value pairs to initialize this context with



This documentation was auto-generated from commit e6bd04a
on September 7, 2022 at 21:06 UTC