fix: change docs and error message for pre-created namespace deployme…

…nt (#785)

fix: change docs and error message for precreated namespace deployment

Signed-off-by: Joshua Silverio <joshua@acorn.io>
Co-authored-by: Craig Jellick <craig.jellick@gmail.com>

docs/docs/50-running/50-namespaces-and-service-accounts.md

@@ -0,0 +1,27 @@
+---
+title: Namespaces and Service Accounts
+---
+## Namespaces 
+
+By design Acorn will run apps under the `acorn` namespace. If you are planning to deploy an app to a pre-created namespace you will need to label it explicitly.
+
+#### To label :
+
+```shell
+kubectl label namespaces <pre-created-namespace> acorn.io/app-name=<test-app>
+kubectl label namespaces <pre-created-namespace> acorn.io/app-namespace=acorn
+```
+#### To verify :
+```shell
+acorn run --target-namespace <pre-created-namespace> -n <test-app> -P ghcr.io/acorn-io/library/hello-world
+acorn % kubectl get pods -n ns-test-app
+NAME                      READY   STATUS    RESTARTS   AGE
+webapp-556947c87d-gt97r   1/1     Running   0          3m54s
+
+```
+:::caution
+When the app is removed the namespace will also be deleted.
+
+## Service Accounts
+
+All Kubernetes deployments launched as part of an Acorn will have a service account attached named "acorn"

pkg/controller/appdefinition/namespace.go

@@ -48,11 +48,12 @@ func ensureNamespaceOwned(req router.Request, appInstance *v1.AppInstance) error
 
 	if ns.Labels[labels.AcornAppNamespace] != appInstance.Namespace ||
 		ns.Labels[labels.AcornAppName] != appInstance.Name {
-		return fmt.Errorf("can not use namespace %s, existing namespace must have labels [%s=%s] and [%s=%s]."+
-			" And namespace will be deleted when the app is deleted",
-			appInstance.Spec.TargetNamespace,
-			ns.Labels[labels.AcornAppNamespace], appInstance.Namespace,
-			ns.Labels[labels.AcornAppName], appInstance.Name)
+		return fmt.Errorf("can not use namespace %s, existing namespace must have labels "+
+			"acorn.io/app-namespace"+" and acorn.io/app-name (Apply Using: kubectl label namespaces %s acorn.io/app-name=%s "+
+			"kubectl label namespaces %s acorn.io/app-namespace=acorn) "+
+			"Namespace will be deleted when the app is deleted",
+			appInstance.Spec.TargetNamespace, appInstance.Spec.TargetNamespace, appInstance.Name,
+			appInstance.Spec.TargetNamespace)
 	}
 	return nil
 }