feat: Allow to restrict the CRs watched according to their labels

Signed-off-by: Wilfried Roset <[email protected]>

deploy/helm/grafana-operator/README.md

@@ -104,5 +104,6 @@ It's easier to just manage this configuration outside of the operator.
 | serviceMonitor.targetLabels | list | `[]` | Set of labels to transfer from the Kubernetes Service onto the target |
 | serviceMonitor.telemetryPath | string | `"/metrics"` | Set path to metrics path |
 | tolerations | list | `[]` | pod tolerations |
+| watchLabelSelectors | object | `{}` | Sets the `WATCH_LABEL_SELECTORS` environment variable, if defines which CRs are watched according to thei labels. By default, the operator watches all CRs. To make it watch only a subset of CRs, set the value to a map of key/value |
 | watchNamespaceSelector | string | `""` | Sets the `WATCH_NAMESPACE_SELECTOR` environment variable, it defines which namespaces the operator should be listening for based on a namespace label (e.g. `"environment: dev"`). By default, the operator watches all namespaces. To make it watch only its own namespace, check out `namespaceScope` option instead. |
 | watchNamespaces | string | `""` | Sets the `WATCH_NAMESPACE` environment variable, it defines which namespaces the operator should be listening for (e.g. `"grafana, foo"`). By default, the operator watches all namespaces. To make it watch only its own namespace, check out `namespaceScope` option instead. |

deploy/helm/grafana-operator/templates/deployment.yaml

@@ -51,6 +51,12 @@ spec:
               {{ else }}
               value: {{quote .Values.watchNamespaceSelector }}
               {{- end }}
+            - name: WATCH_LABEL_SELECTORS
+              {{- if and .Values.watchLabelSelectors (eq .Values.watchLabelSelectors "") }}
+              value: ""
+              {{ else }}
+              value: {{quote .Values.watchLabelSelectors | toJson }}
+              {{- end }}
             {{- with .Values.env }}
               {{- toYaml . | nindent 12 }}
             {{- end }}

deploy/helm/grafana-operator/values.yaml

@@ -15,6 +15,12 @@ watchNamespaces: ""
 # By default, the operator watches all namespaces. To make it watch only its own namespace, check out `namespaceScope` option instead.
 watchNamespaceSelector: ""
 
+# -- Sets the `WATCH_LABEL_SELECTORS` environment variable,
+# if defines which CRs are watched according to thei labels.
+# By default, the operator watches all CRs. To make it watch only a subset of CRs, set the value to a map of key/value
+watchLabelSelectors: {}
+# labelKey: labelValue
+
 # -- Determines if the target cluster is OpenShift. Additional rbac permissions for routes will be added on OpenShift
 isOpenShift: false
 

main.go

@@ -18,6 +18,7 @@ package main
 
 import (
 	"context"
+	"encoding/json"
 	"flag"
 	"os"
 	"os/signal"
@@ -48,6 +49,7 @@ import (
 	"github.com/grafana/grafana-operator/v5/controllers/autodetect"
 	"github.com/grafana/grafana-operator/v5/embeds"
 	"k8s.io/apimachinery/pkg/runtime"
+	"k8s.io/apimachinery/pkg/selection"
 	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	clientgoscheme "k8s.io/client-go/kubernetes/scheme"
 	ctrl "sigs.k8s.io/controller-runtime"
@@ -65,6 +67,10 @@ const (
 	// eg: "environment: dev"
 	// If empty or undefined, the operator will run in cluster scope.
 	watchNamespaceEnvSelector = "WATCH_NAMESPACE_SELECTOR"
+	// watchLabelSelectorsEnvVar is the constant for env variable WATCH_LABEL_SELECTORS which specifies the resources to watch according to their labels.
+	// eg: '{"labelKey": "labelValue"}'
+	// If empty of undefined, the operator will watch all CRs.
+	watchLabelSelectorsEnvVar = "WATCH_LABEL_SELECTORS"
 )
 
 var (
@@ -105,6 +111,7 @@ func main() {
 
 	watchNamespace, _ := os.LookupEnv(watchNamespaceEnvVar)
 	watchNamespaceSelector, _ := os.LookupEnv(watchNamespaceEnvSelector)
+	watchLabelSelectors, _ := os.LookupEnv(watchLabelSelectorsEnvVar)
 
 	controllerOptions := ctrl.Options{
 		Scheme: scheme,
@@ -183,6 +190,23 @@ func main() {
 		setupLog.Info("operator running in cluster scoped mode")
 	}
 
+	if watchLabelSelectors != "" {
+		labelSelectors := map[string]string{}
+		err := json.Unmarshal([]byte(watchLabelSelectors), &labelSelectors)
+		if err != nil {
+			setupLog.Error(err, "unable to Unmarshal labelSelectors")
+			os.Exit(1) //nolint
+		}
+		for k, v := range labelSelectors {
+			req, err := labels.NewRequirement(k, selection.Equals, []string{v}, nil)
+			if err != nil {
+				setupLog.Error(err, "unable to create labels selector")
+				os.Exit(1) //nolint
+			}
+			controllerOptions.Cache.DefaultLabelSelector.Add(*req)
+		}
+	}
+
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGINT, syscall.SIGTERM, syscall.SIGPIPE)
 	defer stop()