Testing Advanced Sync Strategies

Start by reading the articles on

To test the sync waves, lets setup the example app repository using app of apps pattern.

App of Apps Deployment

Start by examining the example apps repo at (argoproj/argocd-example-apps: Example Apps to Demonstrate Argo CD)

Create a new App of Apps with ArgoCD

General Section

  • Application Name : app-of-apps
  • Project : default
  • Sync Policy : manual
  • Set Delete Finalizer : checked

Source Section:

  • Repository URL : https://github.com/argoproj/argocd-example-apps.git
  • Revision: HEAD
  • Path: apps

Destination Section:

  • Cluster URL : https://kubernetes.default.svc (default from dropdown)
  • Namespace : argocd

Create the app and then manually SYNC it. When

Once you sync it, you shall see it creates a group of apps. This is the app of apps pattern. All these apps are added to argocd namespace.

You could validate it from CLI as, 

kubectl get apps -n argocd

[Expected Output]

NAME                  SYNC STATUS   HEALTH STATUS
app-of-apps           Synced        Healthy
helm-guestbook        OutOfSync     Missing
helm-hooks            OutOfSync     Missing
kustomize-guestbook   OutOfSync     Missing
sync-waves            OutOfSync     Missing

kubectl get namespace

[Expected Output]


NAME                  STATUS   AGE
helm-guestbook        Active   62s
helm-hooks            Active   62s
kube-system           Active   34h
kustomize-guestbook   Active   62s
sync-waves            Active   62s

These are the namespaces created by this app of app deployment. In addition you would see your existing namespaces too.

Using Argo Hooks to create Waves

Examine the sync wave manifest here : argocd-example-apps/sync-waves at master · argoproj/argocd-example-apps

Sample code snippets which define the * PreSync Hook * Sync Hook * sync-wave : 0/1/2/3

---
apiVersion: batch/v1
kind: Job
metadata:
  generateName: upgrade-sql-schema
  annotations:
    argocd.argoproj.io/hook: PreSync

apiVersion: batch/v1
kind: Job
metadata:
  name: maint-page-up
  annotations:
    argocd.argoproj.io/hook: Sync
    argocd.argoproj.io/hook-delete-policy: BeforeHookCreation
    argocd.argoproj.io/sync-wave: "1"

apiVersion: apps/v1
kind: ReplicaSet
metadata:
  name: frontend
  annotations:
    argocd.argoproj.io/sync-wave: "2"

apiVersion: batch/v1
kind: Job
metadata:
  name: maint-page-down
  annotations:
    argocd.argoproj.io/hook: Sync
    argocd.argoproj.io/hook-delete-policy: BeforeHookCreation
    argocd.argoproj.io/sync-wave: "3"

start watching for pods in sync-waves namespace 

watch kubectl get pods -n sync-waves

Select sync wave app from ArgoCD and sync it manually.

You will see it syncing in a certain sequence based on the config in the manifest.

You could also observe on the CLI which shows you as the resources are creates/synced

Every 2.0s: kubectl get pods -n sync-waves                                dkr-01: Mon Feb 24 16:34:00 2025

NAME                                                     READY   STATUS      RESTARTS   AGE
pod/backend-c2j4t                                        1/1     Running     0          4m4s
pod/frontend-c6k25                                       1/1     Running     0          3m53s
pod/maint-page-down-llhsl                                0/1     Completed   0          3m49s
pod/maint-page-up-cmqlq                                  0/1     Completed   0          4m
pod/upgrade-sql-schema4773b9f-presync-1740414585-4jzdn   0/1     Completed   0          4m15s

Using Helm Hooks to create Waves

Examine the helm hooks argocd-example-apps/helm-hooks at master · argoproj/argocd-example-apps

Sample code with * helm hooks * pre and post install hooks * hook weights 

apiVersion: batch/v1
kind: Job
metadata:
  generateName: upgrade-sql-schema
  annotations:
    helm.sh/hook: pre-install
    helm.sh/hook-weight: "-2"

---
apiVersion: batch/v1
kind: Job
metadata:
  name: maint-page-up
  annotations:
    helm.sh/hook: pre-install
    helm.sh/hook-delete-policy: before-hook-creation
    helm.sh/hook-weight: "-1"

---
apiVersion: v1
kind: Service
metadata:
  name: frontend
  annotations:
    helm.sh/hook-weight: "2"

---
apiVersion: batch/v1
kind: Job
metadata:
  name: maint-page-down
  annotations:
    helm.sh/hook: post-install
    helm.sh/hook-delete-policy: before-hook-creation

Sync the helm-hooks app to examine how it woks. You will notrice that it helps you achieve the same result as with the sync-waves with argo.

Once you are done experimenting with these examples, clean up everything by removing the app-of-apps application that you created with ArgoCD, which will also clean up the child apps and all the resources created by it.

courses/argo/labs/adv