Enable safe handling of range limits for replicas

Correct drift within limits available for community (hobbyist)
users.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <[email protected]>

Author: alexellis

Dockerfile

@@ -27,7 +27,7 @@ RUN GOOS=${TARGETOS} GOARCH=${TARGETARCH} go build \
         --ldflags "-s -w \
         -X github.com/openfaas/faas-netes/version.GitCommit=${GIT_COMMIT}\
         -X github.com/openfaas/faas-netes/version.Version=${VERSION}" \
-        -a -installsuffix cgo -o faas-netes .
+        -o faas-netes .
 
 FROM --platform=${TARGETPLATFORM:-linux/amd64} alpine:3.17 as ship
 LABEL org.label-schema.license="MIT" \

Makefile

@@ -29,7 +29,7 @@ ${CODEGEN_PKG}: $(TOOLS_DIR)/code-generator.mod
 	@cd $(TOOLS_DIR) && go mod download -modfile=code-generator.mod
 
 local:
-	CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o faas-netes
+	CGO_ENABLED=0 GOOS=linux go build -o faas-netes
 
 build-docker:
 	docker build \

main.go

@@ -15,6 +15,7 @@ import (
 	informers "github.com/openfaas/faas-netes/pkg/client/informers/externalversions"
 	v1 "github.com/openfaas/faas-netes/pkg/client/informers/externalversions/openfaas/v1"
 	"github.com/openfaas/faas-netes/pkg/config"
+	"github.com/openfaas/faas-netes/pkg/controller"
 	"github.com/openfaas/faas-netes/pkg/handlers"
 	"github.com/openfaas/faas-netes/pkg/k8s"
 	"github.com/openfaas/faas-netes/pkg/signals"
@@ -197,6 +198,7 @@ func runController(setup serverSetup) {
 	stopCh := signals.SetupSignalHandler()
 	operator := false
 	listers := startInformers(setup, stopCh, operator)
+	controller.RegisterEventHandlers(listers.DeploymentInformer, kubeClient, config.DefaultFunctionNamespace)
 
 	functionLookup := k8s.NewFunctionLookup(config.DefaultFunctionNamespace, listers.EndpointsInformer.Lister())
 

pkg/controller/controller.go

@@ -368,6 +368,7 @@ func (c *Controller) handleObject(obj interface{}) {
 		}
 		glog.V(4).Infof("Recovered deleted object '%s' from tombstone", object.GetName())
 	}
+
 	glog.V(4).Infof("Processing object: %s", object.GetName())
 	if ownerRef := metav1.GetControllerOf(object); ownerRef != nil {
 		// If this object is not owned by a function, we should not do anything more

pkg/controller/informers.go

@@ -0,0 +1,85 @@
+package controller
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/openfaas/faas-netes/pkg/handlers"
+	appsv1 "k8s.io/api/apps/v1"
+	"k8s.io/apimachinery/pkg/api/errors"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/apimachinery/pkg/labels"
+	v1apps "k8s.io/client-go/informers/apps/v1"
+	"k8s.io/client-go/kubernetes"
+	"k8s.io/client-go/tools/cache"
+	"k8s.io/klog"
+)
+
+func RegisterEventHandlers(deploymentInformer v1apps.DeploymentInformer, kubeClient *kubernetes.Clientset, namespace string) {
+	deploymentInformer.Informer().AddEventHandler(cache.ResourceEventHandlerFuncs{
+		AddFunc: func(obj interface{}) {
+			deployment, ok := obj.(*appsv1.Deployment)
+			if !ok || deployment == nil {
+				return
+			}
+			if err := applyValidation(deployment, kubeClient); err != nil {
+				klog.Info(err)
+			}
+		},
+		UpdateFunc: func(oldObj, newObj interface{}) {
+			deployment, ok := newObj.(*appsv1.Deployment)
+			if !ok || deployment == nil {
+				return
+			}
+			if err := applyValidation(deployment, kubeClient); err != nil {
+				klog.Info(err)
+			}
+		},
+	})
+
+	list, err := deploymentInformer.Lister().Deployments(namespace).List(labels.Everything())
+	if err != nil {
+		klog.Info(err)
+		return
+	}
+
+	for _, deployment := range list {
+		if err := applyValidation(deployment, kubeClient); err != nil {
+			klog.Info(err)
+		}
+	}
+}
+
+func applyValidation(deployment *appsv1.Deployment, kubeClient *kubernetes.Clientset) error {
+	if deployment.Spec.Replicas == nil {
+		return nil
+	}
+
+	if _, ok := deployment.Spec.Template.Labels["faas_function"]; !ok {
+		return nil
+	}
+
+	current := *deployment.Spec.Replicas
+	var target int
+	if current == 0 {
+		target = 1
+	} else if current > handlers.MaxReplicas {
+		target = handlers.MaxReplicas
+	} else {
+		return nil
+	}
+	clone := deployment.DeepCopy()
+
+	value := int32(target)
+	clone.Spec.Replicas = &value
+
+	if _, err := kubeClient.AppsV1().Deployments(deployment.Namespace).
+		Update(context.Background(), clone, metav1.UpdateOptions{}); err != nil {
+		if errors.IsConflict(err) {
+			return nil
+		}
+		return fmt.Errorf("error scaling %s to %d replicas: %w", deployment.Name, value, err)
+	}
+
+	return nil
+}