apis/config,agent: add custom config validation.

Add an interface for custom validation of configuration data.
Update agent to use this interface for extra validation if it
is implemented by the configuration data in use.

Signed-off-by: Krisztian Litkey <[email protected]>

pkg/agent/agent.go

@@ -485,18 +485,8 @@ func (a *Agent) updateNodeConfig(obj runtime.Object) {
 	if cfg == nil {
 		cfg = a.groupCfg
 	}
-	if cfg == nil {
-		log.Warnf("node (%s) has no effective configuration", a.nodeName)
-		return
-	}
-
-	err := a.notifyFn(cfg)
-	if err != nil {
-		log.Errorf("failed to apply configuration: %v", err)
-	}
 
-	a.patchConfigStatus(a.currentCfg, cfg, err)
-	a.currentCfg = cfg
+	a.updateConfig(cfg)
 }
 
 func (a *Agent) updateGroupConfig(obj runtime.Object) {
@@ -535,11 +525,25 @@ func (a *Agent) updateGroupConfig(obj runtime.Object) {
 		return
 	}
 
+	a.updateConfig(cfg)
+}
+
+func (a *Agent) updateConfig(cfg metav1.Object) {
 	if cfg == nil {
 		log.Warnf("node (%s) has no effective configuration", a.nodeName)
 		return
 	}
 
+	if v, ok := cfg.(cfgapi.Validator); ok {
+		if err := v.Validate(); err != nil {
+			log.Errorf("failed to validate configuration: %v", err)
+
+			a.patchConfigStatus(a.currentCfg, cfg, err)
+			a.currentCfg = cfg
+			return
+		}
+	}
+
 	err := a.notifyFn(cfg)
 	if err != nil {
 		log.Errorf("failed to apply configuration: %v", err)

pkg/apis/config/v1alpha1/validator.go

@@ -0,0 +1,22 @@
+// Copyright The NRI Plugins Authors. All Rights Reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package v1alpha1
+
+// Validator is an optional interface that top level configuration types
+// can implement to provide extra custom validation of configuration data.
+// +kubebuilder:object:generate=false
+type Validator interface {
+	Validate() error
+}