# Application Deployment Standard
All applications deployed to Kubernetes MUST use the `apps.devopstoolkit.live` Custom Resource Definition (CRD). Direct usage of Kubernetes Deployments, StatefulSets, or other built-in workload resources for application deployments is not permitted.
## Required CRD
- **API Group**: `devopstoolkit.live`
- **Version**: `v1beta1`
- **Kind**: `App`
This is a Crossplane Composite Resource (XR). It abstracts away underlying Kubernetes workload resources (Deployments, Services, Ingress, HPA) into a single declarative interface.
## Spec Fields
### Required
| Field | Type | Description |
|---------|--------|------------------------------------------------|
| `image` | string | The container image (e.g., `ghcr.io/vfarcic/silly-demo`) |
| `tag` | string | The tag of the image (e.g., `1.2.3`) |
### Optional
| Field | Type | Default | Description |
|--------------------|---------|----------------------|--------------------------------------|
| `host` | string | `devopstoolkit.live` | The host address of the application |
| `port` | integer | `80` | The application port |
| `ingressClassName` | string | `contour` | The Ingress class name |
| `scaling.enabled` | boolean | `false` | Whether to enable scaling |
| `scaling.min` | integer | `1` | Minimum number of replicas |
| `scaling.max` | integer | `10` | Maximum number of replicas |
| `db.name` | string | | The name of the database |
| `db.secret` | string | | The name of the Secret with DB authentication |
| `db.storeName` | string | | The name of the secret store to use |
| `frontend.backendUrl` | string | | The URL of the backend service |
## Example
```yaml
apiVersion: devopstoolkit.live/v1beta1
kind: App
metadata:
name: silly-demo
namespace: a-team
spec:
image: ghcr.io/vfarcic/silly-demo
tag: "1.4.307"
port: 8080
host: silly-demo.devopstoolkit.live
scaling:
enabled: true
min: 2
max: 5
```
## Rationale
The `apps.devopstoolkit.live` CRD provides a standardized abstraction for application deployments that:
- Enforces organizational conventions (naming, labels, annotations) automatically
- Integrates with Crossplane compositions for multi-cloud portability
- Simplifies application manifests by hiding infrastructure complexity
- Ensures consistent networking, scaling, and observability configuration
- Enables policy enforcement through a single resource type
## What NOT to Do
Do not deploy applications using raw Kubernetes resources such as:
- `Deployment` (`apps/v1`)
- `StatefulSet` (`apps/v1`)
- `ReplicaSet` (`apps/v1`)
- `Pod` (`v1`)
These resources should only be created as children of the `App` CRD by the Crossplane composition, never directly by users.
