How to trigger argo workflow from an API request?

Question

What is the best way to trigger an argo workflow from an API request?

The API request is handled by a web server, how does the server submits the workflow to the argo server? Using the CLI? using a rest request? What is the best/recommended approach here?

Answer 1

There's no one "right way." But here are some of the options, so you can pick the one that makes the most sense for your application:

• Use the Argo API

  • with an SDK (Java, Go, Python)

    If your API is written in Java, Go, or Python, and if your interactions with Argo are more complex than simply submitting a Workflow (for example, if you're also listing Workflows and would like a nice representation of those objects), an Argo Workflows SDK might be a good choice. In my experience the SDKs have quirks and bugs, so I'd only dive in if you need a more full-featured client.

  • directly with some HTTP client

    If your use case is very simple (like submitting a small Workflow with a WorkflowTemplate reference), I would recommend using a direct HTTP call to the Argo or Kubernetes API.

• Use a webhook

  The webhook endpoint is technically part of the API, but it's a bit different. The API is basically a specialized version of the Kubernetes API, tailored to the Argo CRDs. The events API endpoint provides some additional features specific to kicking off workflows.

• Use the CLI

  You'd have to fork the CLI process from your server code, so this probably isn't the "cleanest" approach.

• Use Argo Events

  Argo Events is a separate but closely-related project. It can accept a variety of inputs (webhooks, pub/sub messages, etc) and then trigger a Workflow.

  Argo Events could make sense if, for example, you want an external record of all the workflows submitted. Pub/sub would give you that record.

• Use the Kubernetes API or CLI

  Workflows are just Kubernetes resources, so you can just submit them via Kubernetes mechanisms if you like. If your language has a robust Kubernetes SDK, that's a solid choice.

As I'm sure you can tell, it really depends on the application. Let me know if any of these needs clarification.