config: add ignored fields

Specify fields to skip sending object update. Will be applied to all objects.
If after removal of these fields from k8s object all remaining fields will be equal,
handler won't trigger sending update. Removing array elements is not supported.
For example,
```yaml
ignorefields:
  status:
  metadata:
    resourceVersion:
    managedFields:
```
will remove ".status", ".metadata.resourceVersion" and ".metadata.managedFields"
from k8s object before comparing old & new k8s objects.

config/config.go

@@ -94,6 +94,19 @@ type Config struct {
 	// For watching specific namespace, leave it empty for watching all.
 	// this config is ignored when watching namespaces
 	Namespace string `json:"namespace,omitempty"`
+
+	// Specify fields to skip sending object update. Will be applied to all objects.
+	// If after removal of these fields from k8s object all remaining fields will be equal,
+	// handler won't trigger sending update. Removing array elements is not supported.
+	// For example,
+	// ignorefields:
+	//   status:
+	//   metadata:
+	//     resourceVersion:
+	//     managedFields:
+	// will remove ".status", ".metadata.resourceVersion" and ".metadata.managedFields"
+	// from k8s object before comparing old & new k8s objects.
+	IgnoredFields map[string]interface{} `json:"ignoredfields,omitempty"`
 }
 
 // Slack contains slack configuration

go.mod

@@ -4,6 +4,7 @@ go 1.14
 
 require (
 	github.com/fatih/structtag v1.2.0
+	github.com/google/go-cmp v0.6.0
 	github.com/google/go-querystring v0.0.0-20170111101155-53e6ce116135 // indirect
 	github.com/hashicorp/hcl v0.0.0-20171017181929-23c074d0eceb // indirect
 	github.com/inconshreveable/mousetrap v1.0.0 // indirect

pkg/controller/controller.go

@@ -54,6 +54,8 @@ import (
 
 	"github.com/prometheus/client_golang/prometheus"
     "github.com/prometheus/client_golang/prometheus/promauto"
+
+	"github.com/google/go-cmp/cmp"
 )
 
 const maxRetries = 5
@@ -131,7 +133,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		allCoreEventsController := newResourceController(kubeClient, eventHandler, allCoreEventsInformer, objName(api_v1.Event{}), V1, kubewatchEventsMetrics)
+		allCoreEventsController := newResourceController(kubeClient, eventHandler, allCoreEventsInformer, objName(api_v1.Event{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopAllCoreEventsCh := make(chan struct{})
 		defer close(stopAllCoreEventsCh)
 
@@ -155,7 +157,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		allEventsController := newResourceController(kubeClient, eventHandler, allEventsInformer, objName(events_v1.Event{}), EVENTS_V1, kubewatchEventsMetrics)
+		allEventsController := newResourceController(kubeClient, eventHandler, allEventsInformer, objName(events_v1.Event{}), EVENTS_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopAllEventsCh := make(chan struct{})
 		defer close(stopAllEventsCh)
 
@@ -177,7 +179,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Pod{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Pod{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -199,7 +201,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(autoscaling_v1.HorizontalPodAutoscaler{}), AUTOSCALING_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(autoscaling_v1.HorizontalPodAutoscaler{}), AUTOSCALING_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -222,7 +224,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.DaemonSet{}), APPS_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.DaemonSet{}), APPS_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -244,7 +246,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.StatefulSet{}), APPS_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.StatefulSet{}), APPS_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -266,7 +268,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.ReplicaSet{}), APPS_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.ReplicaSet{}), APPS_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -288,7 +290,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Service{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Service{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -310,7 +312,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.Deployment{}), APPS_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(apps_v1.Deployment{}), APPS_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -332,7 +334,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Namespace{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Namespace{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -354,7 +356,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ReplicationController{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ReplicationController{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -376,7 +378,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(batch_v1.Job{}), BATCH_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(batch_v1.Job{}), BATCH_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -398,7 +400,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Node{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Node{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -420,7 +422,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ServiceAccount{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ServiceAccount{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -442,7 +444,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(rbac_v1.ClusterRole{}), RBAC_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(rbac_v1.ClusterRole{}), RBAC_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -464,7 +466,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(rbac_v1.ClusterRoleBinding{}), RBAC_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(rbac_v1.ClusterRoleBinding{}), RBAC_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -486,7 +488,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.PersistentVolume{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.PersistentVolume{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -508,7 +510,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Secret{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.Secret{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -530,7 +532,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ConfigMap{}), V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(api_v1.ConfigMap{}), V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -552,7 +554,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, objName(networking_v1.Ingress{}), NETWORKING_V1, kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, objName(networking_v1.Ingress{}), NETWORKING_V1, kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -583,7 +585,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 			cache.Indexers{},
 		)
 
-		c := newResourceController(kubeClient, eventHandler, informer, crd.Resource, fmt.Sprintf("%s/%s", crd.Group, crd.Version), kubewatchEventsMetrics)
+		c := newResourceController(kubeClient, eventHandler, informer, crd.Resource, fmt.Sprintf("%s/%s", crd.Group, crd.Version), kubewatchEventsMetrics, conf.IgnoredFields)
 		stopCh := make(chan struct{})
 		defer close(stopCh)
 
@@ -596,7 +598,7 @@ func Start(conf *config.Config, eventHandler handlers.Handler) {
 	<-sigterm
 }
 
-func newResourceController(client kubernetes.Interface, eventHandler handlers.Handler, informer cache.SharedIndexInformer, resourceType string, apiVersion string, kubewatchEventsMetrics *prometheus.CounterVec) *Controller {
+func newResourceController(client kubernetes.Interface, eventHandler handlers.Handler, informer cache.SharedIndexInformer, resourceType string, apiVersion string, kubewatchEventsMetrics *prometheus.CounterVec, ignoredFields map[string]interface{}) *Controller {
 	queue := workqueue.NewRateLimitingQueue(workqueue.DefaultControllerRateLimiter())
 	var newEvent Event
 	var err error
@@ -634,6 +636,15 @@ func newResourceController(client kubernetes.Interface, eventHandler handlers.Ha
 			if !ok {
 				logrus.WithField("pkg", "kubewatch-"+resourceType).Errorf("cannot convert old to runtime.Object for update on %v", old)
 			}
+			if len(ignoredFields) > 0 {
+				diff, errDiff := diffObjects(old, new, ignoredFields)
+				if errDiff != nil {
+					logrus.WithField("pkg", "kubewatch-"+resourceType).Errorf("cannot diff old & new objects %v and %v: %v", old, new, errDiff)
+				} else if len(diff) == 0 {
+					logrus.WithField("pkg", "kubewatch-"+resourceType).Infof("Ignoring update to %v: %s", resourceType, newEvent.key)
+					return
+				}
+			}
 			logrus.WithField("pkg", "kubewatch-"+resourceType).Infof("Processing update to %v: %s", resourceType, newEvent.key)
 			if err == nil {
 				queue.Add(newEvent)
@@ -670,6 +681,38 @@ func newResourceController(client kubernetes.Interface, eventHandler handlers.Ha
 	}
 }
 
+func diffObjects(old, new interface{}, ignoredFields map[string]interface{}) (string, error) {
+	oldContent, err := runtime.DefaultUnstructuredConverter.ToUnstructured(old)
+	if err != nil {
+		return "", err
+	}
+	newContent, err := runtime.DefaultUnstructuredConverter.ToUnstructured(new)
+	if err != nil {
+		return "", err
+	}
+	recursiveDelete(oldContent, ignoredFields)
+	recursiveDelete(newContent, ignoredFields)
+	return cmp.Diff(oldContent, newContent), nil
+}
+
+// recursiveDelete recursively removes key from object
+// value of key should be either nil or nested map[string]interface{}
+// value of object to delete from should be nested map[string]interface{}
+func recursiveDelete(object map[string]interface{}, key map[string]interface{}) {
+	for k, v := range key {
+		if v == nil {
+			delete(object, k)
+			continue
+		}
+		if recursiveKey, ok := v.(map[string]interface{}); ok {
+			if recursiveObj, ok := object[k].(map[string]interface{}); ok {
+				recursiveDelete(recursiveObj, recursiveKey)
+			}
+		}
+	}
+	return
+}
+
 // Run starts the kubewatch controller
 func (c *Controller) Run(stopCh <-chan struct{}) {
 	defer utilruntime.HandleCrash()