Introduction & Architecture

Argo Workflows is an open-source, container-level workflow engine designed to orchestrate parallel jobs on Kubernetes. It leverages Kubernetes Custom Resource Definitions (CRDs) to implement its full architecture, including Workflow, Workflow Template, and Cron Workflow.

What Can Argo Workflows Do?

  • Define workflows where each step is a container.
  • Model multi-step workflows as a sequence of tasks or capture task dependencies using Directed Acyclic Graphs (DAGs).
  • Easily run compute-intensive jobs—such as machine learning or data processing—on Kubernetes within a short time frame.
  • Run CI/CD pipelines natively on Kubernetes without configuring complex software development tooling.

Key Features of Argo Workflows:

  • Workflow: Orchestrates multiple workflow templates with customizable execution order.
  • Workflow Template: A reusable template definition for workflows; can be invoked by other workflows or templates within the same namespace or cluster.
  • Cluster Workflow Template: A cluster-scoped workflow template accessible across all namespaces via ClusterRole permissions.
  • Cron Workflow: Scheduled workflow type, equivalent to an advanced version of Kubernetes CronJob.

Installation & Configuration

Install Argo Workflows

We are installing the stable version 2.12.10. The installation process sets up ServiceAccount, Role, ClusterRole, Deployment, and other necessary components.

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kubectl create ns argo
kubectl apply -n argo -f https://raw.githubusercontent.com/argoproj/argo/v2.12.10/manifests/install.yaml

Configure Ingress for External Access

Since our cluster uses Traefik as the ingress controller, and Argo Workflows defaults to internal HTTPS access, we need to add specific annotations to route external requests to argo-server.

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apiVersion: extensions/v1beta1
kind: Ingress
metadata:
  annotations:
    kubernetes.io/ingress.class: traefik
    traefik.ingress.kubernetes.io/redirect-entry-point: https
  name: argo-server
  namespace: argo
spec:
  rules:
  - host: argo.test.cn
    http:
      paths:
      - backend:
          serviceName: argo-server
          servicePort: web
        path: /
status:
  loadBalancer: {}

External access URL: https://argo.test.cn

Simple Workflow Test

Let’s test with a “Hello World” example:

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# argo submit -n argo --watch https://raw.githubusercontent.com/argoproj/argo-workflows/master/examples/hello-world.yaml
Name:                hello-world-4mffd
Namespace:           argo
ServiceAccount:      default
Status:              Pending
Created:             Fri May 07 16:11:25 +0800 (now)
Name:                hello-world-4mffd
Namespace:           argo
ServiceAccount:      default
Status:              Running
Created:             Fri May 07 16:11:25 +0800 (now)
Started:             Fri May 07 16:11:25 +0800 (now)
Duration:            0 seconds

STEP                  TEMPLATE  PODNAME            DURATION  MESSAGE
 ◷ hello-world-4mffd  whalesay  hello-world-4mffd  0s
Name:                hello-world-4mffd
Namespace:           argo
ServiceAccount:      default
Status:              Running
Created:             Fri May 07 16:11:25 +0800 (10 seconds ago)
Started:             Fri May 07 16:11:25 +0800 (10 seconds ago)
Duration:            10 seconds

STEP                  TEMPLATE  PODNAME            DURATION  MESSAGE
 ◷ hello-world-4mffd  whalesay  hello-world-4mffd  10s       ContainerCreating
Name:                hello-world-4mffd
Namespace:           argo
ServiceAccount:      default
Status:              Succeeded
Conditions:
 Completed           True
Created:             Fri May 07 16:11:25 +0800 (2 minutes ago)
Started:             Fri May 07 16:11:25 +0800 (2 minutes ago)
Finished:            Fri May 07 16:14:18 +0800 (now)
Duration:            2 minutes 53 seconds
ResourcesDuration:   1m18s*cpu,1m18s*memory

STEP                  TEMPLATE  PODNAME            DURATION  MESSAGE
 ✔ hello-world-4mffd  whalesay  hello-world-4mffd  2m

# argo list -n argo
NAME                STATUS      AGE   DURATION   PRIORITY
hello-world-4mffd   Succeeded   3m    2m         0

# argo logs -f hello-world-4mffd -n argo
hello-world-4mffd:  _____________
hello-world-4mffd: < hello world >
hello-world-4mffd:  -------------
hello-world-4mffd:     \
hello-world-4mffd:      \
hello-world-4mffd:       \
hello-world-4mffd:                     ##        .
hello-world-4mffd:               ## ## ##       ==
hello-world-4mffd:            ## ## ## ##      ===
hello-world-4mffd:        /""""""""""""""""___/ ===
hello-world-4mffd:   ~~~ {~~ ~~~~ ~~~ ~~~~ ~~ ~ /  ===- ~~~
hello-world-4mffd:        \______ o          __/
hello-world-4mffd:         \    \        __/
hello-world-4mffd:           \____\______/