prefect.context
¶
Async and thread safe models for passing runtime context data.
These contexts should never be directly mutated by the user.
For more user-accessible information about the current run, see prefect.runtime
.
ContextModel
¶
Bases: BaseModel
A base model for context data that forbids mutation and extra data while providing a context manager
Source code in prefect/context.py
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copy
¶
Duplicate the context model, optionally choosing which fields to include, exclude, or change.
Attributes:
Name | Type | Description |
---|---|---|
include |
Fields to include in new model. |
|
exclude |
Fields to exclude from new model, as with values this takes precedence over include. |
|
update |
Values to change/add in the new model. Note: the data is not validated before creating the new model - you should trust this data. |
|
deep |
Set to |
Returns:
Type | Description |
---|---|
A new model instance. |
Source code in prefect/context.py
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EngineContext
¶
Bases: RunContext
The context for a flow run. Data in this context is only available from within a flow run function.
Attributes:
Name | Type | Description |
---|---|---|
flow |
Optional[Flow]
|
The flow instance associated with the run |
flow_run |
Optional[FlowRun]
|
The API metadata for the flow run |
task_runner |
BaseTaskRunner
|
The task runner instance being used for the flow run |
task_run_futures |
List[PrefectFuture]
|
A list of futures for task runs submitted within this flow run |
task_run_states |
List[State]
|
A list of states for task runs created within this flow run |
task_run_results |
Dict[int, State]
|
A mapping of result ids to task run states for this flow run |
flow_run_states |
List[State]
|
A list of states for flow runs created within this flow run |
sync_portal |
Optional[BlockingPortal]
|
A blocking portal for sync task/flow runs in an async flow |
timeout_scope |
Optional[CancelScope]
|
The cancellation scope for flow level timeouts |
Source code in prefect/context.py
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PrefectObjectRegistry
¶
Bases: ContextModel
A context that acts as a registry for all Prefect objects that are registered during load and execution.
Attributes:
Name | Type | Description |
---|---|---|
start_time |
DateTimeTZ
|
The time the object registry was created. |
block_code_execution |
bool
|
If set, flow calls will be ignored. |
capture_failures |
bool
|
If set, failures during init will be silenced and tracked. |
Source code in prefect/context.py
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register_instances
classmethod
¶
Decorator for a class that adds registration to the PrefectObjectRegistry
on initialization of instances.
Source code in prefect/context.py
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RunContext
¶
Bases: ContextModel
The base context for a flow or task run. Data in this context will always be
available when get_run_context
is called.
Attributes:
Name | Type | Description |
---|---|---|
start_time |
DateTimeTZ
|
The time the run context was entered |
client |
Union[PrefectClient, SyncPrefectClient]
|
The Prefect client instance being used for API communication |
Source code in prefect/context.py
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SettingsContext
¶
Bases: ContextModel
The context for a Prefect settings.
This allows for safe concurrent access and modification of settings.
Attributes:
Name | Type | Description |
---|---|---|
profile |
Profile
|
The profile that is in use. |
settings |
Settings
|
The complete settings model. |
Source code in prefect/context.py
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TagsContext
¶
Bases: ContextModel
The context for prefect.tags
management.
Attributes:
Name | Type | Description |
---|---|---|
current_tags |
Set[str]
|
A set of current tags in the context |
Source code in prefect/context.py
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TaskRunContext
¶
Bases: RunContext
The context for a task run. Data in this context is only available from within a task run function.
Attributes:
Name | Type | Description |
---|---|---|
task |
Task
|
The task instance associated with the task run |
task_run |
TaskRun
|
The API metadata for this task run |
Source code in prefect/context.py
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get_run_context
¶
Get the current run context from within a task or flow function.
Returns:
Type | Description |
---|---|
Union[FlowRunContext, TaskRunContext]
|
A |
Raises RuntimeError: If called outside of a flow or task run.
Source code in prefect/context.py
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get_settings_context
¶
Get the current settings context which contains profile information and the settings that are being used.
Generally, the settings that are being used are a combination of values from the
profile and environment. See prefect.context.use_profile
for more details.
Source code in prefect/context.py
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registry_from_script
¶
Return a fresh registry with instances populated from execution of a script.
Source code in prefect/context.py
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root_settings_context
¶
Return the settings context that will exist as the root context for the module.
The profile to use is determined with the following precedence
- Command line via 'prefect --profile
Source code in prefect/context.py
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tags
¶
Context manager to add tags to flow and task run calls.
Tags are always combined with any existing tags.
Yields:
Type | Description |
---|---|
Set[str]
|
The current set of tags |
Examples:
>>> from prefect import tags, task, flow
>>> @task
>>> def my_task():
>>> pass
Run a task with tags
>>> @flow
>>> def my_flow():
>>> with tags("a", "b"):
>>> my_task() # has tags: a, b
Run a flow with tags
>>> @flow
>>> def my_flow():
>>> pass
>>> with tags("a", "b"):
>>> my_flow() # has tags: a, b
Run a task with nested tag contexts
>>> @flow
>>> def my_flow():
>>> with tags("a", "b"):
>>> with tags("c", "d"):
>>> my_task() # has tags: a, b, c, d
>>> my_task() # has tags: a, b
Inspect the current tags
>>> @flow
>>> def my_flow():
>>> with tags("c", "d"):
>>> with tags("e", "f") as current_tags:
>>> print(current_tags)
>>> with tags("a", "b"):
>>> my_flow()
{"a", "b", "c", "d", "e", "f"}
Source code in prefect/context.py
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use_profile
¶
Switch to a profile for the duration of this context.
Profile contexts are confined to an async context in a single thread.
Parameters:
Name | Type | Description | Default |
---|---|---|---|
profile |
Union[Profile, str]
|
The name of the profile to load or an instance of a Profile. |
required |
override_environment_variable |
If set, variables in the profile will take precedence over current environment variables. By default, environment variables will override profile settings. |
required | |
include_current_context |
bool
|
If set, the new settings will be constructed with the current settings context as a base. If not set, the use_base settings will be loaded from the environment and defaults. |
True
|
Yields:
Type | Description |
---|---|
The created |
Source code in prefect/context.py
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