Hera

	Hera is the go-to Python SDK to make Argo Workflows simple and intuitive. Easily turn Python functions into containerised templates that run on Kubernetes, with full access to its capabilities.

See the Quick Start guide to start using Hera to orchestrate your Argo Workflows!

The Argo was constructed by the shipwright Argus,
and its crew were specially protected by the goddess Hera.

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Repo information

Hera at a glance

from hera.workflows import DAG, Workflow, script


# Turn a function into a reusable "Script template"
# using the script decorator
@script()
def echo(message: str):
    print(message)


# Orchestration logic lives *outside* of business logic
with Workflow(
    generate_name="dag-diamond-",
    entrypoint="diamond",
) as w:
    with DAG(name="diamond"):
        A = echo(name="A", arguments={"message": "A"})
        B = echo(name="B", arguments={"message": "B"})
        C = echo(name="C", arguments={"message": "C"})
        D = echo(name="D", arguments={"message": "D"})
        A >> [B, C] >> D  # Define execution order

# Create the workflow directly on your Argo Workflows cluster!
w.create()

Check out the Walkthrough to learn how to construct and submit Argo Workflows with Hera!

Requirements

Hera requires an Argo Workflows server to be deployed to a Kubernetes cluster. To learn how to deploy Argo to your own Kubernetes cluster you can follow the Argo Workflows guide!

Authenticating in Hera

Hera assumes that the Argo server sits behind an authentication layer, so workflow submission requests are authenticated using a Bearer token on the request. Another option for workflow submission without the authentication layer is using port forwarding to your Argo server deployment and submitting workflows to localhost:2746.

There are a few ways to authenticate in Hera - read more in the authentication walkthrough - for now, with the argo cli tool installed, and the server port-forwarded to localhost:2746, this example will get you up and running:

from hera.workflows import Workflow, Container
from hera.shared import global_config
from hera.auth import ArgoCLITokenGenerator

global_config.host = "http://localhost:2746"
global_config.token = ArgoCLITokenGenerator

with Workflow(generate_name="local-test-", entrypoint="c") as w:
    Container(name="c", image="docker/whalesay", command=["cowsay", "hello"])

w.create()

Installation

Optional dependencies

yaml

• Install via hera[yaml]
• PyYAML is required for the yaml output format, which is accessible via hera.workflows.Workflow.to_yaml(*args, **kwargs). This enables GitOps practices and easier debugging.

cli

• Install via hera[cli]. The [cli] option installs the extra dependencies including Cappa which is required for the CLI
• The CLI aims to enable GitOps practices, easier onboarding to Hera, and a more seamless experience with Argo Workflows.
• It currently supports converting workflows between YAML and Python source codes. See hera generate yaml --help, and hera generate python --help for more information.
• The CLI is an experimental feature and subject to change!

experimental

• Install via hera[experimental]. The [experimental] option adds dependencies required for experimental features that have not yet graduated into stable features.

async-client

• Install via hera[async-client]. The [async-client] option installs httpx to allow the use of the async_* Workflow functions through the AsyncWorkflowsService.

Presentations

• KubeCon/ArgoCon EU 2025 - One Engine To Rule Them All: Unifying Cloud Workloads With Argo Workflows
• KubeCon/ArgoCon NA 2024 - Data Science Workflows Made Easy: Python-Powered Argo for Your Organization
• KubeCon/ArgoCon EU 2024 - Orchestrating Python Functions Natively in Argo Using Hera

Blogs

• Hera Developer Survey 2025
• How To Get the Most out of Hera for Data Science
• Data Validation with Great Expectations and Argo Workflows

Contributing

Use one of the following to open the repo in a cloud dev box:

Read more in the contributing guide!

Hera Emeritus Maintainers

These emeritus maintainers dedicated a part of their career to Hera and reviewed code, triaged bugs and pushed the project forward over a substantial period of time. Their contribution is greatly appreciated:

• Flaviu Vadan

License

Hera is licensed under Apache 2.0. See License for details.