ArgoCD sync waves between apps

Question

We have an ArgoCD project. In this project we have multiple apps (lets call them A, B, and C), which pass messages to each other via a Kafka cluster. In order to do this the topics need to be created.

App A is responsible for managing the Kafka cluster (amongst other things). We have a PreSync hook in app A for a job to create and configure the topics before updating the other resources, which apps B and C depend on.

This means that we need app A to sync before the other apps to ensure smooth rollout. To try to manage this we added app A to SyncWave -1, with others in the default 0

kind: Application
metadata:
  name: "A"
  annotations:
    argocd.argoproj.io/sync-wave: "-1"

Our original assumption (perhaps foolishly) was that sync coordination applied within a project, however, it seems that it is only applied within an app.

So what happens is that the resources in app A wait for the PreSync hook to provision the topics as expected, but apps B and C do not wait for app A to be in sync.

Is there a way to control the order / dependencies of syncing between apps inside a project?

I have seen mention of an "app-of-apps" pattern, where you have one app which deploys all other apps. Would doing this allow us to leverage the SyncWave to ensure that app A fully resolves before attempting to sync apps B and C? If not, is there another way?

Answer 1

We have an app-of-apps (bootstrap app) and that is how we orchestrate sync-waves between apps. I have had no luck however ALSO adding sync-waves to the manifests IN each app. Seems from the docs that manifests are applied by Kind (e.g., namespaces first) and then alphabetically by name (case insensitive).

Answer 2

As of version 1.8 of ArgoCD the part responsible for making this possible has been removed. More details can be found here .

The argocd-cm will need to be updated to enable the app of an app health check using resource.customizations part like on below example. More details can be found here and here.

---
apiVersion: v1
kind: ConfigMap
metadata:
  name: argocd-cm
  namespace: argocd
  labels:
    app.kubernetes.io/name: argocd-cm
    app.kubernetes.io/part-of: argocd
data:
  resource.customizations: |
    argoproj.io/Application:
      health.lua: |
        hs = {}
        hs.status = "Progressing"
        hs.message = ""
        if obj.status ~= nil then
          if obj.status.health ~= nil then
            hs.status = obj.status.health.status
            if obj.status.health.message ~= nil then
              hs.message = obj.status.health.message
            end
          end
        end
        return hs