How to prevent Argo Workflow from being resubmitted if it is already running?

user_562440 0
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The use case is that we think about triggering an Argo Workflow via Argo Events with PubSub. PubSub does not guarantee that a message is delivered only once. Is there an easy method to prevent a Workflow from being triggered again when it is running already?

Something like the concurrencyPolicy setting for CronWorkflows.

To have something to look at - let's assume the whalesay Workflow:

apiVersion: argoproj.io/v1alpha1
kind: Workflow                  # new type of k8s spec
metadata:
  name: hello-world    # name of the workflow spec
  namespace: argo
spec:
  entrypoint: whalesay          # invoke the whalesay template
  templates:
  - name: whalesay              # name of the template
    container:
      image: docker/whalesay
      command: [cowsay]
      args: ["hello world"]
      resources:                # limit the resources
        limits:
          memory: 32Mi
          cpu: 100m

I found the following two promising issues - but I fail to extract the solution for this problem.

argoproj argo-workflows synchronization
1 Answers

If you just need to make sure the Workflow doesn't run more than one simultaneous instance, use Argo's built-in synchronization feature.

apiVersion: v1
kind: ConfigMap
metadata:
 name: my-config
data:
  workflow: "1"  # Only one workflow can run at given time in particular namespace

---

apiVersion: argoproj.io/v1alpha1
kind: Workflow 
metadata:
  name: hello-world
spec:
  entrypoint: whalesay
  synchronization:
    semaphore:
      configMapKeyRef:
        name: my-config
        key: workflow
  templates:
  - name: whalesay
    container:
      image: docker/whalesay
# ...

If you want to avoid processing the same message twice, you could add a step to the workflow to exit early if the message ID is in a database (or something along those lines).

user_6847760
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