ArgoWorkflow Template Definitions Types

In this lesson/article we will learn about template types in Argo Workflows. Templates can be thought of like functions: they define the instructions to execute. The spec of a workflow includes an entrypoint field that specifies the “main” template — the template executed first. There are nine template types in total, split into two categories: template definitions and template invokers. Below is a brief overview of each.

A presentation slide titled "Template Types" showing two sections: "Template Definitions" (01 Container, 02 Script, 03 Resource, 04 Suspend, 05 Container Set, 06 HTTP, 07 Plugin) and "Template Invokers" (01 Steps, 02 DAG). The slide has a KodeKloud copyright at the bottom.

Container template (definition)

The container template is the most common template type. It schedules a Kubernetes container and its spec follows the same container fields as a Kubernetes Pod container (image, command, args, env, resources, volume mounts, etc.). Use it whenever you want to run a container image directly.

Script template (definition)

The script template is a convenience wrapper around a container. It provides the same container fields (image, command) and adds a source field where you can embed a script directly. Argo writes the source into a file inside the container and executes it using the provided command.

When using a script template, make sure the command you provide runs the interpreter (for example, python) and that the image includes that interpreter. The script content is placed into a file and executed inside the container.

Example script template:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: random-number-
spec:
  entrypoint: random-number
  templates:
  - name: random-number
    script:
      image: python:3.6-alpine
      command: [python]
      source: |
        import random
        i = random.randint(100, 2000)
        print(i)

Resource template (definition)

Use resource templates to create, apply, delete, or patch Kubernetes resources from within an Argo workflow. The manifest to manage is provided inline in the manifest field.

Example that creates a ConfigMap:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: k8s-resource-
spec:
  entrypoint: k8s-resource
  templates:
  - name: k8s-resource
    resource:
      action: create
      manifest: |
        apiVersion: v1
        kind: ConfigMap
        metadata:
          generateName: dev-env-
        data:
          key: value

Suspend template (definition)

A suspend template pauses workflow execution. You can suspend for a duration (using the duration field) or indefinitely until a manual resume. Resuming can be done via the CLI, the API, or the UI.

Example suspend template and resume command:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: delay-
spec:
  entrypoint: delay
  templates:
  - name: delay
    suspend:
      duration: "20s"

CLI resume (example):

argo -n argo resume delay-xyzb

ContainerSet template (definition)

The containerSet template runs multiple containers in the same pod (useful when you want sidecars or co-located containers that share volumes and localhost networking). The field is containerSet and contains an array of containers.

Example:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: container-set-template-
spec:
  entrypoint: main
  templates:
  - name: main
    containerSet:
      containers:
      - name: a
        image: rancher/cowsay
        command: [cowsay]
        args: ["Container A!!!!"]
      - name: b
        image: rancher/cowsay
        command: [cowsay]
        args: ["Container B!!!!"]

HTTP template (definition)

An HTTP template performs HTTP(S) requests. The response body is automatically exported into the template’s result output parameter. You can specify the URL, method (defaults to GET), headers, and body.

Example:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: http-template-example-
spec:
  entrypoint: fetch-todo-item
  templates:
  - name: fetch-todo-item
    http:
      url: "https://x.y.com/todos/1"
      method: "GET"
      headers:
      - name: "Content-Type"
        value: "application/json"

Plugin template (definition)

Plugin templates let Argo workflows use executor plugins, extending behavior without modifying Argo core. Built-in and third-party plugins are supported. In the example below, the ArgoCD plugin is used to trigger a sync of applications, so no container is executed; Argo connects to an ArgoCD server and performs the action.

Example using the ArgoCD plugin:

apiVersion: argoproj.io/v1alpha1
kind: Workflow
metadata:
  generateName: argocd-example-
spec:
  entrypoint: main
  templates:
  - name: main
    plugin:
      argocd:
        serverUrl: https://my-argocd.com/
        actions:
        - sync:
            project: highway-animation
            apps:
            - highway-animation
            - health-check-app

Template invokers

Steps and DAG templates are the two invoker types. They don’t execute work themselves but define how other templates (definitions) are invoked and composed into a workflow. Use Steps for sequential/parallel step-based flows and DAG for dependency-based execution graphs.

With these template types you can express a wide variety of orchestration patterns — from simple container tasks to complex multi-resource automation and integrations with other systems.

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Demo simple Workflow using CLI or UI

Parameters

ArgoCD

Argo Workflow

Argo Rollouts

Argo Events

Introduction

ArgoWorkflow Template Definitions Types

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