Workflow Features

This section signposts some more Workflow features found in Argo, which are beyond the scope of the Walkthrough.

Workflow-Level Lifecycle Hooks

Lifecycle hooks are typically used to run a given template, according to the given condition, such as on workflow exit, or when the workflow has a Running status.

• Read more about Lifecycle Hooks on the Argo docs
• See the Workflow-level lifecycle hook example

Exit Handlers (deprecated)

Exit handlers are templates that always execute (regardless of success or failure) at the end of a workflow. They were replaced by workflow-level (above) and template-level hooks.

Some use cases listed from Argo Workflows include:

• cleaning up after a workflow runs
• sending notifications of workflow status (e.g. e-mail/Slack)
• posting the pass/fail status to a web-hook result (e.g. GitHub build result)
• resubmitting or submitting another workflow

To use an exit handler on a Workflow in Hera, you can either define the template to use within the workflow, then set the on_exit member which will take the name from the template itself, or specify the template to use as a string when initializing the Workflow object. See both methods below.

with Workflow(
    generate_name="exit-handler-workflow-",
) as w1:
    cleanup_exit_handler = Container(
        name="cleanup",
        image="docker/whalesay",
        command=["cowsay"],
        args=["cleanup!"],
    )
    w1.on_exit = cleanup_exit_handler
    ...

with Workflow(
    generate_name="exit-handler-workflow-",
    on_exit="cleanup",
) as w2:
    cleanup_exit_handler = Container(
        name="cleanup",
        image="docker/whalesay",
        command=["cowsay"],
        args=["cleanup!"],
    )
    ...

Volume Claim Templates

Volume Claim Templates can be used to copy a large amount data from one step to another in a Workflow.

See the Empty Volume example for creating a volume dynamically for the Workflow, or the Existing Volumes example for using an existing volume.

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