feat: instantiate global plugins in Kong via labelling

There are cases where a plugin(s) should be executed for all proxied
requests. In order to do this with the existing model, it becomes
cumbersome to configure it for 100s of different services and would make
sense to configure globally for all services. This feature is already
supported by Kong.

With this change, all KongPlugin resources that have a label of
`"global" : "true"` will be setup as global plugins in Kong
by the Ingress controller.

internal/ingress/controller/kong.go

@@ -30,16 +30,16 @@ import (
 
 	"github.com/fatih/structs"
 	"github.com/golang/glog"
-	configurationv1 "github.com/kong/kubernetes-ingress-controller/internal/apis/configuration/v1"
-	"github.com/pkg/errors"
-	extensions "k8s.io/api/extensions/v1beta1"
-	"k8s.io/apimachinery/pkg/util/sets"
-
 	kong "github.com/kong/kubernetes-ingress-controller/internal/apis/admin"
 	kongadminv1 "github.com/kong/kubernetes-ingress-controller/internal/apis/admin/v1"
+	configurationv1 "github.com/kong/kubernetes-ingress-controller/internal/apis/configuration/v1"
+	pluginv1 "github.com/kong/kubernetes-ingress-controller/internal/apis/plugin/v1"
 	"github.com/kong/kubernetes-ingress-controller/internal/ingress"
 	"github.com/kong/kubernetes-ingress-controller/internal/ingress/annotations"
 	"github.com/kong/kubernetes-ingress-controller/internal/net/ssl"
+	"github.com/pkg/errors"
+	extensions "k8s.io/api/extensions/v1beta1"
+	"k8s.io/apimachinery/pkg/util/sets"
 )
 
 // OnUpdate is called periodically by syncQueue to keep the configuration in sync.
@@ -92,6 +92,11 @@ func (n *NGINXController) OnUpdate(ingressCfg *ingress.Configuration) error {
 		return err
 	}
 
+	err = n.syncGlobalPlugins()
+	if err != nil {
+		return err
+	}
+
 	checkServices, err := n.syncServices(ingressCfg)
 	if err != nil {
 		return err
@@ -114,6 +119,91 @@ func (n *NGINXController) OnUpdate(ingressCfg *ingress.Configuration) error {
 	return nil
 }
 
+func (n *NGINXController) syncGlobalPlugins() error {
+	glog.Infof("syncing global plugins")
+
+	targetGlobalPlugins, err := n.store.ListGlobalKongPlugins()
+	if err != nil {
+		return err
+	}
+	targetPluginMap := make(map[string]*pluginv1.KongPlugin)
+	var duplicates []string // keep track of duplicate
+
+	for i := 0; i < len(targetGlobalPlugins); i++ {
+		name := targetGlobalPlugins[i].Name
+		// empty name skip it
+		if name == "" {
+			continue
+		}
+		if _, ok := targetPluginMap[name]; ok {
+			glog.Error("Multiple KongPlugin definitions found with 'global' annotation for :", name,
+				", the plugin will not be applied")
+			duplicates = append(duplicates, name)
+			continue
+		}
+		targetPluginMap[name] = targetGlobalPlugins[i]
+	}
+
+	// remove duplicates
+	for _, plugin := range duplicates {
+		delete(targetPluginMap, plugin)
+	}
+
+	client := n.cfg.Kong.Client
+	plugins, err := client.Plugins().List(nil)
+	if err != nil {
+		return err
+	}
+
+	// plugins in Kong
+	currentGlobalPlugins := make(map[string]kongadminv1.Plugin)
+	for _, plugin := range plugins.Items {
+		if plugin.Route == "" && plugin.Service == "" && plugin.Consumer == "" {
+			currentGlobalPlugins[plugin.Name] = plugin
+		}
+	}
+
+	// sync plugins to Kong
+	for pluginName, kongPlugin := range targetPluginMap {
+		// plugin exists?
+		if pluginInKong, ok := currentGlobalPlugins[pluginName]; !ok {
+			// no, create it
+			p := &kongadminv1.Plugin{
+				Name:   pluginName,
+				Config: kongadminv1.Configuration(kongPlugin.Config),
+			}
+			_, res := client.Plugins().CreateGlobal(p)
+			if res.StatusCode != http.StatusCreated {
+				return errors.Wrap(res.Error(), fmt.Sprintf("creating a global Kong plugin %v", p))
+			}
+		} else {
+			// plugin exists, is the configuration up to date
+			if !pluginDeepEqual(kongPlugin.Config, &pluginInKong) {
+				// no, update it
+				p := &kongadminv1.Plugin{
+					Name:   pluginName,
+					Config: kongadminv1.Configuration(kongPlugin.Config),
+				}
+				_, res := client.Plugins().Patch(pluginInKong.ID, p)
+				if res.StatusCode != http.StatusOK {
+					return errors.Wrap(res.Error(), fmt.Sprintf("updating a global Kong plugin %v", p))
+				}
+			}
+		}
+		// remove from the current list, all that remain in the current list will be deleted
+		delete(currentGlobalPlugins, pluginName)
+	}
+
+	// delete the ones not configured in k8s
+	for _, plugin := range currentGlobalPlugins {
+		err := client.Plugins().Delete(plugin.ID)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 // syncTargets reconciles the state between the ingress controller and
 // kong comparing the endpoints in Kubernetes and the targets in a
 // particular kong upstream. To avoid downtimes we create the new targets