flytekit.PythonFunctionTask

class flytekit.PythonFunctionTask(*args, **kwargs)[source]

A Python Function task should be used as the base for all extensions that have a python function. It will automatically detect interface of the python function and when serialized on the hosted Flyte platform handles the writing execution command to execute the function

It is advised this task is used using the @task decorator as follows

In the above code, the name of the function, the module, and the interface (inputs = int and outputs = str) will be auto detected.

Parameters
  • task_config (T) – Configuration object for Task. Should be a unique type for that specific Task

  • task_function (Callable) – Python function that has type annotations and works for the task

  • ignore_input_vars (Optional[List[str]]) – When supplied, these input variables will be removed from the interface. This can be used to inject some client side variables only. Prefer using ExecutionParams

  • execution_mode (Optional[ExecutionBehavior]) – Defines how the execution should behave, for example executing normally or specially handling a dynamic case.

  • task_type (Optional[TaskResolverMixin]) – String task type to be associated with this Task

Methods

compile(ctx, *args, **kwargs)

Generates a node that encapsulates this task in a workflow definition.

Parameters

ctx (flytekit.core.context_manager.FlyteContext) –

compile_into_workflow(ctx, task_function, **kwargs)[source]

In the case of dynamic workflows, this function will produce a workflow definition at execution time which will then proceed to be executed.

Parameters
Return type

Union[flytekit.models.core.dynamic_job.DynamicJobSpec, flytekit.models.core.literals.LiteralMap]

construct_node_metadata()

Used when constructing the node that encapsulates this task as part of a broader workflow definition.

Return type

flytekit.models.core.workflow.NodeMetadata

dispatch_execute(ctx, input_literal_map)

This method translates Flyte’s Type system based input values and invokes the actual call to the executor This method is also invoked during runtime.

  • VoidPromise is returned in the case when the task itself declares no outputs.

  • Literal Map is returned when the task returns either one more outputs in the declaration. Individual outputs may be none

  • DynamicJobSpec is returned when a dynamic workflow is executed

Parameters
Return type

Union[flytekit.models.core.literals.LiteralMap, flytekit.models.core.dynamic_job.DynamicJobSpec]

dynamic_execute(task_function, **kwargs)[source]

By the time this function is invoked, the local_execute function should have unwrapped the Promises and Flyte literal wrappers so that the kwargs we are working with here are now Python native literal values. This function is also expected to return Python native literal values.

Since the user code within a dynamic task constitute a workflow, we have to first compile the workflow, and then execute that workflow.

When running for real in production, the task would stop after the compilation step, and then create a file representing that newly generated workflow, instead of executing it.

Parameters

task_function (Callable) –

Return type

Any

execute(**kwargs)[source]

This method will be invoked to execute the task. If you do decide to override this method you must also handle dynamic tasks or you will no longer be able to use the task as a dynamic task generator.

Return type

Any

find_lhs()
Return type

str

get_command(settings)

Returns the command which should be used in the container definition for the serialized version of this task registered on a hosted Flyte platform.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

List[str]

get_config(settings)

Returns the task config as a serializable dictionary. This task config consists of metadata about the custom defined for this task.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

Dict[str, str]

get_container(settings)

Returns the container definition (if any) that is used to run the task on hosted Flyte.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

flytekit.models.core.task.Container

get_custom(settings)

Return additional plugin-specific custom data (if any) as a serializable dictionary.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

Dict[str, Any]

get_default_command(settings)

Returns the default pyflyte-execute command used to run this on hosted Flyte platforms.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

List[str]

get_input_types()

Returns the names and python types as a dictionary for the inputs of this task.

Return type

Optional[Dict[str, type]]

get_k8s_pod(settings)

Returns the kubernetes pod definition (if any) that is used to run the task on hosted Flyte.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

flytekit.models.core.task.K8sPod

get_sql(settings)

Returns the Sql definition (if any) that is used to run the task on hosted Flyte.

Parameters

settings (flytekit.core.context_manager.SerializationSettings) –

Return type

Optional[flytekit.models.core.task.Sql]

get_type_for_input_var(k, v)

Returns the python type for an input variable by name.

Parameters
  • k (str) –

  • v (Any) –

Return type

Optional[Type[Any]]

get_type_for_output_var(k, v)

Returns the python type for the specified output variable by name.

Parameters
  • k (str) –

  • v (Any) –

Return type

Optional[Type[Any]]

local_execute(ctx, **kwargs)

This function is used only in the local execution path and is responsible for calling dispatch execute. Use this function when calling a task with native values (or Promises containing Flyte literals derived from Python native values).

Parameters

ctx (flytekit.core.context_manager.FlyteContext) –

Return type

Union[Tuple[flytekit.core.promise.Promise], flytekit.core.promise.Promise, flytekit.core.promise.VoidPromise]

post_execute(user_params, rval)

Post execute is called after the execution has completed, with the user_params and can be used to clean-up, or alter the outputs to match the intended tasks outputs. If not overridden, then this function is a No-op

Parameters
Return type

Any

pre_execute(user_params)

This is the method that will be invoked directly before executing the task method and before all the inputs are converted. One particular case where this is useful is if the context is to be modified for the user process to get some user space parameters. This also ensures that things like SparkSession are already correctly setup before the type transformers are called

This should return either the same context of the mutated context

Parameters

user_params (flytekit.common.tasks.sdk_runnable.ExecutionParameters) –

Return type

flytekit.common.tasks.sdk_runnable.ExecutionParameters

reset_command_fn()

Resets the command which should be used in the container definition of this task to the default arguments. This is useful when the command line is overridden at serialization time.

set_command_fn(get_command_fn=None)

By default, the task will run on the Flyte platform using the pyflyte-execute command. However, it can be useful to update the command with which the task is serialized for specific cases like running map tasks (“pyflyte-map-execute”) or for fast-executed tasks.

Parameters

get_command_fn (Optional[Callable[[flytekit.core.context_manager.SerializationSettings], List[str]]]) –

Attributes

container_image
environment

Any environment variables that supplied during the execution of the task.

execution_mode
instantiated_in
interface
lhs
location
metadata
name
python_interface

Returns this task’s python interface.

resources
security_context
task_config

Returns the user-specified task config which is used for plugin-specific handling of the task.

task_function
task_resolver
task_type
task_type_version