Quick Start

Install in GitHub Codespaces

You can install Argo and try running Hera code in GitHub Codespaces. First, open the Hera repository in Codespaces using the link below:

Then, you can run the make commands to install k3d (a lightweight Kubernetes CLI), and then install the Argo Workflows controller on the cluster:

make install-k3d run-argo

You can take a look at test_submission.py to see how to submit a Workflow using Hera and write your own. You can run the test Workflow using:

make test-on-cluster

See the Viewing the Argo UI from a Codespace guide to see the Workflow in the UI.

Otherwise you can install the Argo CLI with

make install-argo

which will then let you do things like listing the Workflows in the argo namespace with

argo list --namespace argo

Install locally

Install Argo tools

Ensure you have a Kubernetes cluster, kubectl and Argo Workflows installed by following the Argo Workflows Quick Start.

Ensure you are able to submit a workflow to Argo as in the example:

argo submit -n argo --watch https://raw.githubusercontent.com/argoproj/argo-workflows/master/examples/hello-world.yaml

Install Hera

Hera is available on PyPi as the hera package. Add this dependency to your project in your usual way, e.g. pip or poetry, or install directly with pip install hera.

Hello World

If you were able to run the argo submit command above, copy the following Workflow definition into a local file hello_world.py.

from hera.workflows import Steps, Workflow, WorkflowsService, script


@script()
def echo(message: str):
    print(message)


with Workflow(
    generate_name="hello-world-",
    entrypoint="steps",
    namespace="argo",
    workflows_service=WorkflowsService(host="https://localhost:2746")
) as w:
    with Steps(name="steps"):
        echo(arguments={"message": "Hello world!"})

w.create()

Run the file

python -m hello_world

You will then see the Workflow at https://localhost:2746/

Using an existing Argo installation

If you or your organization are already running on Argo and you’re interested in using Hera to write your Workflow definitions, you will need to set up some config variables in hera.shared.global_config. Copy the following as a basis and fill in the blanks.

from hera.workflows import Steps, Workflow, script
from hera.shared import global_config

global_config.host = "https://<your-host-name>"
global_config.token = ""  # Copy token value after "Bearer" from the `argo auth token` command
global_config.image = "<your-image-repository>/python:3.9"  # Set the image if you cannot access "python:3.9" via Docker Hub


@script()
def echo(message: str):
    print(message)


with Workflow(
    generate_name="hello-world-",
    entrypoint="steps",
    namespace="argo",
) as w:
    with Steps(name="steps"):
        echo(arguments={"message": "Hello world!"})

w.create()