Build Lightweight Python Components
Out of dateThis guide contains outdated information pertaining to Kubeflow 1.0. This guide needs to be updated for Kubeflow 1.1.
Lightweight Python components do not require you to build a new container image for every code change. They’re intended for fast iteration in a notebook environment.
Advantages over container components:
- Faster iteration: No need to build new container image after every change (building images takes some time).
- Easier authoring: Components can be created in a local environment. Docker and Kubernetes are not required.
Building a lightweight Python component
To build a component, define a stand-alone Python function and then call
kfp.components.func_to_container_op(func) to convert the function to a
component that can be used in a pipeline.
There are several requirements for the component function:
The function must be stand-alone.
- It should not use any code declared outside the function definition.
- Any imports should be added inside the main component function.
- Any helper functions should also be defined inside the main component function.
The function can only import packages that are available in the base image.
- If you need to import a package that’s not available in the default base
image you can try to find a container image that already includes the
required packages. (As a workaround you can use the
subprocessmodule to run
pip installfor the required package.)
- If you need to import a package that’s not available in the default base image you can try to find a container image that already includes the required packages. (As a workaround you can use the
If the function operates on numbers, the parameters must have type hints. Supported types are
bool. All other arguments are passed as strings.
To build a component with multiple output values, use Python’s typing.NamedTuple type hint syntax:
NamedTuple('MyFunctionOutputs', [('output_name_1', type), ('output_name_2', float)])
NamedTupleclass is already imported, so that it can be used in the function declaration.
See the notebook on lightweight Python component basics for an example of creating lightweight Python components and using them in a pipeline.
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