Advanced Hera Features
This section is used to publicize Hera’s features beyond the essentials covered in the walk through. Note that these
features do not exist in Argo as they are specific to the hera module.
Pre-Build Hooks
Hera offers a pre-build hook feature through hera.shared.register_pre_build_hook with huge flexibility to do pre-build
processing on any type of template or Workflow. For example, it can be used to conditionally set the image of a
Script, or set which cluster to submit a Workflow to.
To use this feature, you can write a function that takes an object of type template or Workflow, does some
processing on the object, then returns it.
For a simple example, we’ll write a function that adds an annotation with key “hera”, value “This workflow was submitted through Hera!”
from hera.shared import register_pre_build_hook
from hera.workflows import Workflow
@register_pre_build_hook
def set_workflow_default_labels(workflow: Workflow) -> Workflow:
if workflow.annotations is None:
workflow.annotations = {}
workflow.annotations["hera-annotation"] = "This workflow was submitted through Hera!"
return workflow
Now, any time build is called on the Workflow (e.g. to submit it or dump it to yaml), it will add in the annotation!
Experimental Features
From time to time, Hera will release a new feature under the “experimental feature” flag while we develop the feature
and ensure stability. Currently this is used for the RunnerScriptConstructor seen in the
runner script example.
To enable experimental features you must set the feature by name to True in the global_config.experimental_features
dictionary before using the feature: