Merge pull request #13325 from xordspar0/configmap-error-msg

Improve the error message for usused configMaps

docs/source/markdown/podman-play-kube.1.md

@@ -72,9 +72,11 @@ disable builds.
 
 `Kubernetes ConfigMap`
 
-Kubernetes ConfigMap can be referred as a source of environment variables in Pods or Deployments.
+Kubernetes ConfigMap can be referred as a source of environment variables or volumes in Pods or Deployments.
+ConfigMaps aren't a standalone object in Podman; instead, when a container uses a ConfigMap, Podman will create environment variables or volumes as needed.
+
+For example, the following YAML document defines a ConfigMap and then uses it in a Pod:
 
-For example ConfigMap defined in following YAML:
 ```
 apiVersion: v1
 kind: ConfigMap
@@ -82,14 +84,11 @@ metadata:
   name: foo
 data:
     FOO: bar
-```
+---
-
-can be referred in a Pod in following way:
-```
 apiVersion: v1
 kind: Pod
 metadata:
-...
+  name: foobar
 spec:
   containers:
   - command:

pkg/domain/infra/abi/play.go

@@ -128,6 +128,9 @@ func (ic *ContainerEngine) PlayKube(ctx context.Context, path string, options en
 	}
 
 	if validKinds == 0 {
+		if len(configMaps) > 0 {
+			return nil, fmt.Errorf("ConfigMaps in podman are not a standalone object and must be used in a container")
+		}
 		return nil, fmt.Errorf("YAML document does not contain any supported kube kind")
 	}