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app set

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Danijel Simeunovic
2026-02-08 13:36:48 +01:00
parent 774852bd1b
commit 08931e4677
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APPLICATIONSET_GUIDE.md Normal file
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# ApplicationSet Guide
## Overview
This repository uses **ApplicationSet** (instead of the traditional app-of-apps pattern) to manage infrastructure applications. ApplicationSet automatically discovers and creates ArgoCD Applications based on a git directory pattern.
## How It Works
### ApplicationSet Definition
Located in `argocd/_app-of-apps.yaml`:
```yaml
apiVersion: argoproj.io/v1alpha1
kind: ApplicationSet
metadata:
name: infrastructure-apps
namespace: argocd
spec:
goTemplate: true
generators:
- git:
repoURL: https://github.com/fortedigital/sturdy-adventure.git
revision: HEAD
directories:
- path: argocd/infra/*.yaml
template:
# Template applied to each discovered file
```
### Key Components
1. **Generator**: Scans `argocd/infra/*.yaml` for all Application manifests
2. **Path Variables**: Each match provides template variables:
- `{{ .path.basenameNormalized }}` - filename without extension (e.g., "prometheus")
- `{{ .path.dir }}` - directory path (e.g., "argocd/infra")
3. **Template**: Used to create consistent Applications from the discovered files
## How Applications Are Created
When you create a new file `argocd/infra/my-app.yaml`:
```yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: my-app
# ... other config
spec:
# ... your application spec
```
The ApplicationSet:
1. Discovers the file matching `argocd/infra/*.yaml`
2. Extracts metadata: `basenameNormalized=my-app`, `dir=argocd/infra`
3. Renders the template with these variables
4. Creates an Application resource with:
- Name: `my-app`
- Labels applied from the template
- Sync policy inherited from template
- Source path: `argocd/infra`
## Adding New Applications
### Step 1: Create Application YAML
Create `argocd/infra/my-new-app.yaml`:
```yaml
apiVersion: argoproj.io/v1alpha1
kind: Application
metadata:
name: my-new-app
annotations:
argocd.argoproj.io/sync-wave: "2" # Optional: control sync ordering
spec:
project: default
source:
repoURL: https://my-helm-repo.com
chart: my-chart
targetRevision: "1.0.0"
helm:
releaseName: my-new-app
destination:
server: https://kubernetes.default.svc
namespace: my-namespace
# Note: syncPolicy is applied from the ApplicationSet template
# No need to duplicate it here
```
### Step 2: Push to Repository
```bash
git add argocd/infra/my-new-app.yaml
git commit -m "Add my-new-app infrastructure application"
git push
```
### Step 3: Verify Discovery
```bash
# View all generated applications
kubectl get applications -n argocd
# Check ApplicationSet status
kubectl describe applicationset infrastructure-apps -n argocd
# Watch for your new application
kubectl get application my-new-app -n argocd -w
```
## Template Variables
The ApplicationSet template uses these variables for each discovered file:
| Variable | Example | Description |
|----------|---------|-------------|
| `{{ .path.basenameNormalized }}` | `prometheus` | Filename without extension |
| `{{ .path.dir }}` | `argocd/infra` | Directory containing the file |
| `{{ .path.path }}` | `argocd/infra/prometheus.yaml` | Full path to the file |
## ApplicationSet Features Used
### 1. Git Directory Generator
```yaml
generators:
- git:
repoURL: https://github.com/fortedigital/sturdy-adventure.git
revision: HEAD
directories:
- path: argocd/infra/*.yaml # Match all YAML files
```
Automatically discovers applications in the git repository.
### 2. Go Templating
```yaml
goTemplate: true
```
Enables Go template syntax for variable interpolation (e.g., `{{ .path.basenameNormalized }}`).
### 3. Dynamic Application Generation
```yaml
template:
metadata:
name: "{{ .path.basenameNormalized }}"
labels:
app.kubernetes.io/name: "{{ .path.basenameNormalized }}"
```
Each discovered file generates an Application with consistent configuration.
## Benefits Over App-of-Apps Pattern
| Feature | ApplicationSet | App-of-Apps |
|---------|---|---|
| Auto-discovery | ✅ Automatic | ❌ Manual list required |
| New app onboarding | 1 file created | 1 file created + parent update |
| Consistency | ✅ Template enforced | ❌ Manual consistency |
| Scalability | ✅ Grows automatically | ❌ Manual maintenance |
| RBAC per app | ✅ Supported | ❌ Limited |
| Drift detection | ✅ Per app | ✅ Per app |
## Sync Policy Applied by ApplicationSet
All generated Applications inherit this sync policy from the template:
```yaml
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions:
- CreateNamespace=true
- Validate=true
- ServerSideApply=true
timeout: 300s
retry:
limit: 5
backoff:
duration: 5s
factor: 2
maxDuration: 3m
```
**What this means:**
- ✅ Automatic syncing when repository changes
- ✅ Automatic pruning of deleted resources
- ✅ Self-healing if cluster drifts from git
- ✅ Namespace auto-creation if missing
- ✅ Manifest validation before applying
- ✅ Server-side apply for field ownership
- ✅ 5-minute timeout per application sync
- ✅ Up to 5 retry attempts with exponential backoff
## Monitoring ApplicationSet
### View ApplicationSet Status
```bash
kubectl describe applicationset infrastructure-apps -n argocd
```
Output shows:
- Condition status (Healthy, Progressing, etc.)
- Number of applications created
- Last sync time
- Error messages if any
### View Generated Applications
```bash
# All applications created by this ApplicationSet
kubectl get applications -n argocd -l app.kubernetes.io/managed-by=argocd
# View a specific application
kubectl get application prometheus -n argocd -o yaml
```
### Check Sync Status
```bash
# Watch all applications
kubectl get applications -n argocd -w
# Detailed sync status
argocd app list
# Application health
kubectl get applications -n argocd -o wide
```
## Troubleshooting
### ApplicationSet Not Creating Applications
**Problem**: Files in `argocd/infra/` but no Applications created
**Solutions**:
1. Check file naming: Must end with `.yaml` (not `.yml`)
2. Verify path: Files must be in `argocd/infra/` (not subdirectories)
3. Check permissions: Repository URL must be accessible
4. Review ApplicationSet status: `kubectl describe applicationset infrastructure-apps -n argocd`
### Application Created But Not Syncing
**Problem**: Application exists but stays in "OutOfSync" state
**Solutions**:
1. Check application spec is valid YAML
2. Verify `destination.server` is accessible: `https://kubernetes.default.svc`
3. Check `destination.namespace` exists or `CreateNamespace=true` is set
4. Review application logs: `kubectl logs -n argocd deployment/argocd-application-controller`
### ApplicationSet Generates Duplicate Applications
**Problem**: Same application created multiple times
**Solutions**:
1. Check for duplicate files in `argocd/infra/` with same name
2. Clear git cache: `git clean -fd`
3. ApplicationSet may take time to reconcile; wait 60 seconds
## Best Practices
1. **File Organization**
- Keep only Application manifests in `argocd/infra/`
- Don't mix other resource types (ConfigMaps, Secrets, etc.)
- Use consistent naming: `lowercase-with-hyphens.yaml`
2. **Application Design**
- Keep each Application spec in the discovered file
- Don't rely on syncPolicy being defined in the Application (it comes from ApplicationSet)
- Use sync waves for dependency ordering
3. **Repository Management**
- All files in `argocd/infra/` should be valid Kubernetes manifests
- Regular commits to track changes
- Use branches for testing new applications before merging
4. **Monitoring**
- Regularly check ApplicationSet status
- Monitor generated applications for sync status
- Set up alerts for Failed or Degraded applications
5. **Updates**
- Update application specs directly in `argocd/infra/` files
- ApplicationSet changes take effect within 60 seconds
- Test in dev environment first
## Related Documentation
- [ArgoCD ApplicationSet Docs](https://argocd-applicationset.readthedocs.io/)
- [ArgoCD Application Spec](https://argo-cd.readthedocs.io/en/stable/operator-manual/declarative-setup/#applications)
- [Kubernetes Application Convention](https://kubernetes.io/docs/concepts/overview/working-with-objects/labels/#recommended-labels)

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argocd/_app-of-apps.yaml
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apiVersion: argoproj.io/v1alpha1
kind: Application
kind: ApplicationSet
metadata:
name: app-of-apps
name: infrastructure-apps
namespace: argocd
labels:
scope: infra
spec:
project: default
source:
repoURL: https://github.com/fortedigital/sturdy-adventure.git
targetRevision: HEAD
path: argocd
directory:
recurse: true
destination:
server: https://kubernetes.default.svc
namespace: argocd
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions:
- CreateNamespace=true
- Validate=true
- ServerSideApply=true
goTemplate: true
generators:
- git:
repoURL: https://github.com/fortedigital/sturdy-adventure.git
revision: HEAD
directories:
- path: argocd/infra/*.yaml
template:
metadata:
name: "{{ .path.basenameNormalized }}"
labels:
app.kubernetes.io/name: "{{ .path.basenameNormalized }}"
app.kubernetes.io/part-of: platform
app.kubernetes.io/managed-by: argocd
spec:
project: default
source:
repoURL: https://github.com/fortedigital/sturdy-adventure.git
targetRevision: HEAD
path: "{{ .path.dir }}"
destination:
server: https://kubernetes.default.svc
namespace: argocd
syncPolicy:
automated:
prune: true
selfHeal: true
syncOptions:
- CreateNamespace=true
- Validate=true
- ServerSideApply=true
timeout: 300s
retry:
limit: 5
backoff:
duration: 5s
factor: 2
maxDuration: 3m

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bootstrap.sh
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helm upgrade --install argocd argo-cd \
--repo https://argoproj.github.io/argo-helm \
--namespace argocd --create-namespace \
--values argocd-values.yaml \
--values argocd/values/argocd-values.yaml \
--timeout 60s --atomic
}