feat: add feature gates to the controller manager

go.mod

@@ -30,6 +30,7 @@ require (
  k8s.io/apiextensions-apiserver v0.22.2
  k8s.io/apimachinery v0.22.2
  k8s.io/client-go v0.22.2
+ k8s.io/component-base v0.22.2
  knative.dev/networking v0.0.0-20210914225408-69ad45454096
  knative.dev/pkg v0.0.0-20210919202233-5ae482141474
  knative.dev/serving v0.26.0
@@ -118,7 +119,6 @@ require (
  gopkg.in/inf.v0 v0.9.1 // indirect
  gopkg.in/yaml.v2 v2.4.0 // indirect
  gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
- k8s.io/component-base v0.22.2 // indirect
  k8s.io/klog/v2 v2.9.0 // indirect
  k8s.io/kube-openapi v0.0.0-20210421082810-95288971da7e // indirect
  k8s.io/utils v0.0.0-20210819203725-bdf08cb9a70a // indirect

internal/manager/config.go

@@ -9,6 +9,7 @@ import (
  "github.com/spf13/pflag"
  "k8s.io/client-go/rest"
  "k8s.io/client-go/tools/clientcmd"
+ cliflag "k8s.io/component-base/cli/flag"
  "sigs.k8s.io/controller-runtime/pkg/client"
 
  "github.com/kong/kubernetes-ingress-controller/v2/internal/adminapi"
@@ -81,6 +82,9 @@ type Config struct {
  EnableProfiling bool
  EnableConfigDumps bool
  DumpSensitiveConfig bool
+
+ // Feature Gates
+ FeatureGates map[string]bool
 }
 
 // -----------------------------------------------------------------------------
@@ -182,6 +186,10 @@ func (c *Config) FlagSet() *pflag.FlagSet {
  flagSet.Int("stderrthreshold", 0, "DEPRECATED: has no effect and will be removed in future releases (see github issue #1297)")
  flagSet.Bool("update-status-on-shutdown", false, `DEPRECATED: no longer has any effect and will be removed in a later release (see github issue #1304)`)
 
+ // Feature Gates (see FEATURE_GATES.md)
+ flagSet.Var(cliflag.NewMapStringBool(&c.FeatureGates), "feature-gates", "A set of key=value pairs that describe feature gates for alpha/beta/experimental features. "+
+ fmt.Sprintf("See the Feature Gates documentation for information and available options: %s", featureGatesDocsURL))
+
  return flagSet
 }
 

internal/manager/feature_gates.go

@@ -0,0 +1,52 @@
+package manager
+
+import (
+ "fmt"
+
+ "github.com/go-logr/logr"
+
+ "github.com/kong/kubernetes-ingress-controller/v2/internal/util"
+)
+
+// featureGatesDocsURL provides a link to the documentation for feature gates in the KIC repository
+const featureGatesDocsURL = "https:/Kong/kubernetes-ingress-controller/blob/main/FEATURE_GATES.md"
+
+// setupFeatureGates converts feature gates to controller enablement
+func setupFeatureGates(setupLog logr.Logger, c *Config) error {
+ // if there are no configurations then bail out
+ if len(c.FeatureGates) < 1 {
+ setupLog.V(util.DebugLevel).Info("no feature gates configured")
+ return nil
+ }
+
+ // generate a map of feature gates by string names to their controller enablement
+ ctrlMap := getFeatureGateControllerMapping(c)
+
+ // find each feature gate option and process it
+ for feature, enabled := range c.FeatureGates {
+ setupLog.Info("found configuration option for gated feature", "feature", feature, "enabled", enabled)
+ ctrlEnabled, ok := ctrlMap[feature]
+ if !ok {
+ return fmt.Errorf("%s is not a valid feature, please see the documentation: %s", feature, featureGatesDocsURL)
+ }
+ *ctrlEnabled = enabled
+ }
+
+ return nil
+}
+
+// getFeatureGateControllerMapping provides a map[string]*bool for a given *Config where the keys
+// reference pointers to the enablement value for the controller of relevant feature gates by name.
+//
+// NOTE: if you're adding a new feature gate, it needs to be added here.
+func getFeatureGateControllerMapping(c *Config) map[string]*bool {
+ return map[string]*bool{
+ "KongPlugin": &c.KongPluginEnabled,
+ "KongClusterPlugin": &c.KongClusterPluginEnabled,
+ "KongIngress": &c.KongIngressEnabled,
+ "TCPIngress": &c.TCPIngressEnabled,
+ "UDPIngress": &c.UDPIngressEnabled,
+ "KongConsumer": &c.KongConsumerEnabled,
+ "Knative": &c.KnativeIngressEnabled,
+ }
+}

internal/manager/run.go

@@ -42,6 +42,11 @@ func Run(ctx context.Context, c *Config, diagnostic util.ConfigDumpDiagnostic) e
  utilruntime.Must(configurationv1beta1.AddToScheme(scheme))
  utilruntime.Must(knativev1alpha1.AddToScheme(scheme))
 
+ setupLog.Info("getting enabled options and features")
+ if err := setupFeatureGates(setupLog, c); err != nil {
+ return fmt.Errorf("failed to configure feature gates: %w", err)
+ }
+
  setupLog.Info("getting the kubernetes client configuration")
  kubeconfig, err := c.GetKubeconfig()
  if err != nil {