Change initializer for resource scaler (#20)

Author: levrado

cmd/autoscaler/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.12-rc-alpine3.8
+FROM golang:1.10-alpine3.7
 
 RUN apk --update --no-cache add \
     git \

cmd/autoscaler/app/autoscaler.go

@@ -40,7 +40,8 @@ func Run(kubeconfigPath string,
 	if err != nil {
 		return errors.Wrap(err, "Failed to initialize plugin loader")
 	}
-	resourceScaler, err := pluginLoader.Load()
+
+	resourceScaler, err := pluginLoader.Load(kubeconfigPath, namespace)
 	if err != nil {
 		return errors.Wrap(err, "Failed to load plugin")
 	}

cmd/autoscaler/main.go

@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/v3io/scaler/cmd/autoscaler/app"
+	"github.com/v3io/scaler/pkg/common"
 
 	"github.com/nuclio/errors"
 )
@@ -20,6 +21,8 @@ func main() {
 	scaleThreshold := flag.Int64("scale-threshold", 0, "Maximum allowed value for metric to be considered below active")
 	flag.Parse()
 
+	*namespace = common.GetNamespace(*namespace)
+
 	if err := app.Run(*kubeconfigPath,
 		*namespace,
 		*scaleInterval,

cmd/dlx/Dockerfile

@@ -1,4 +1,4 @@
-FROM golang:1.12-rc-alpine3.8
+FROM golang:1.10-alpine3.7
 
 RUN apk --update --no-cache add \
     git \

cmd/dlx/app/dlx.go

@@ -11,13 +11,18 @@ import (
 	"github.com/v3io/scaler-types"
 )
 
-func Run(namespace string, targetNameHeader string, targetPathHeader string, targetPort int, listenAddress string) error {
+func Run(kubeconfigPath string,
+	namespace string,
+	targetNameHeader string,
+	targetPathHeader string,
+	targetPort int,
+	listenAddress string) error {
 	pluginLoader, err := pluginloader.New()
 	if err != nil {
 		return errors.Wrap(err, "Failed to initialize plugin loader")
 	}
 
-	resourceScaler, err := pluginLoader.Load()
+	resourceScaler, err := pluginLoader.Load(kubeconfigPath, namespace)
 	if err != nil {
 		return errors.Wrap(err, "Failed to load plugin")
 	}

cmd/dlx/main.go

@@ -5,19 +5,23 @@ import (
 	"os"
 
 	"github.com/v3io/scaler/cmd/dlx/app"
+	"github.com/v3io/scaler/pkg/common"
 
 	"github.com/nuclio/errors"
 )
 
 func main() {
+	kubeconfigPath := flag.String("kubeconfig-path", os.Getenv("KUBECONFIG"), "Path of kubeconfig file")
 	namespace := flag.String("namepsace", "", "Kubernetes namespace")
 	targetNameHeader := flag.String("target-name-header", "", "Name of the header that holds information on target name")
 	targetPathHeader := flag.String("target-path-header", "", "Name of the header that holds information on target path")
 	targetPort := flag.Int("target-port", 0, "Name of the header that holds information on target port")
 	listenAddress := flag.String("listen-address", ":8090", "Address to listen upon for http proxy")
 	flag.Parse()
 
-	if err := app.Run(*namespace, *targetNameHeader, *targetPathHeader, *targetPort, *listenAddress); err != nil {
+	*namespace = common.GetNamespace(*namespace)
+
+	if err := app.Run(*kubeconfigPath, *namespace, *targetNameHeader, *targetPathHeader, *targetPort, *listenAddress); err != nil {
 		errors.PrintErrorStack(os.Stderr, err, 5)
 
 		os.Exit(1)

pkg/common/namespaceresolver.go

@@ -0,0 +1,26 @@
+package common
+
+import (
+	"io/ioutil"
+	"os"
+)
+
+func GetNamespace(namespaceArgument string) string {
+
+	// if the namespace was passed in the arguments, use that
+	if namespaceArgument != "" {
+		return namespaceArgument
+	}
+
+	// if the namespace exists in env, use that
+	if namespaceEnv := os.Getenv("SCALER_NAMESPACE"); namespaceEnv != "" {
+		return namespaceEnv
+	}
+
+	// get namespace from within the pod. if found, return that
+	if namespacePod, err := ioutil.ReadFile("/var/run/secrets/kubernetes.io/serviceaccount/namespace"); err == nil {
+		return string(namespacePod)
+	}
+
+	return "default"
+}

pkg/pluginloader/loader.go

@@ -8,15 +8,15 @@ import (
 	"github.com/v3io/scaler-types"
 )
 
-type resourceScalerNewFunc func() (scaler_types.ResourceScaler, error)
+type resourceScalerNewFunc func(string, string) (scaler_types.ResourceScaler, error)
 
 type PluginLoader struct{}
 
 func New() (*PluginLoader, error) {
 	return &PluginLoader{}, nil
 }
 
-func (p *PluginLoader) Load() (scaler_types.ResourceScaler, error) {
+func (p *PluginLoader) Load(kubeconfigPath string, namespace string) (scaler_types.ResourceScaler, error) {
 	var funcNew resourceScalerNewFunc
 	var ok bool
 
@@ -37,11 +37,12 @@ func (p *PluginLoader) Load() (scaler_types.ResourceScaler, error) {
 			return nil, errors.Wrap(err, "Failed to find New symbol")
 		}
 
-		funcNew, ok = symbol.(func() (scaler_types.ResourceScaler, error))
+		// don't use resourceScalerNewFunc as the cast type cause of some bug :(
+		funcNew, ok = symbol.(func(string, string) (scaler_types.ResourceScaler, error))
 		if !ok {
 			return nil, errors.New("Failed to cast New function of plugin")
 		}
 	}
 
-	return funcNew()
+	return funcNew(kubeconfigPath, namespace)
 }

pkg/resourcescaler/resourcescaler.go

@@ -6,7 +6,7 @@ import (
 
 type NopResourceScaler struct{}
 
-func New() (scaler_types.ResourceScaler, error) { // nolint: deadcode
+func New(kubeconfigPath string, namespace string) (scaler_types.ResourceScaler, error) { // nolint: deadcode
 	return &NopResourceScaler{}, nil
 }