Set default max scale to 5 replicas and a 10% increment

Sets a new default maximum scale limit of 5 replicas out of
the box for CE users, CE meaning "Community" rather than
"Commercial".

The increment factor of 10 vs 25 should not make a difference
to genuine community and hobbyist users.

Tested and verified with unit tests and hey with a CE cluster
where the maximum limit was reached over several minutes,
finally going back to 1 replica.

Signed-off-by: Alex Ellis (OpenFaaS Ltd) <alexellis2@gmail.com>

gateway/handlers/alerthandler.go

@@ -102,6 +102,7 @@ func scaleService(alert requests.PrometheusInnerAlert, service scaling.ServiceQu
 func CalculateReplicas(status string, currentReplicas uint64, maxReplicas uint64, minReplicas uint64, scalingFactor uint64) uint64 {
 	var newReplicas uint64
 
+	maxReplicas = uint64(math.Min(float64(maxReplicas), float64(scaling.DefaultMaxReplicas)))
 	step := uint64(math.Ceil(float64(maxReplicas) / 100 * float64(scalingFactor)))
 
 	if status == "firing" && step > 0 {

gateway/handlers/alerthandler_test.go

@@ -1,4 +1,4 @@
-// Copyright (c) Alex Ellis 2017. All rights reserved.
+// Copyright (c) Alex Ellis 1017. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
 package handlers
@@ -12,9 +12,9 @@ import (
 func TestDisabledScale(t *testing.T) {
 	minReplicas := uint64(1)
 	scalingFactor := uint64(0)
-	newReplicas := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != minReplicas {
-		t.Logf("Expected not to scale, but replicas were: %d", newReplicas)
+	got := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+	if got != minReplicas {
+		t.Logf("Expected not to scale, but replicas were: %d", got)
 		t.Fail()
 	}
 }
@@ -22,20 +22,23 @@ func TestDisabledScale(t *testing.T) {
 func TestParameterEdge(t *testing.T) {
 	minReplicas := uint64(0)
 	scalingFactor := uint64(0)
-	newReplicas := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 0 {
+	got := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+	if got != 0 {
 		t.Log("Expected not to scale")
 		t.Fail()
 	}
 }
 
-func TestScalingWithSameUpperLowerLimit(t *testing.T) {
-	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	//	status string, currentReplicas uint64, maxReplicas uint64, minReplicas uint64, scalingFactor uint64)
-	newReplicas := CalculateReplicas("firing", minReplicas, minReplicas, minReplicas, scalingFactor)
-	if newReplicas != 1 {
-		t.Logf("Replicas - want: %d, got: %d", minReplicas, newReplicas)
+func TestScaling_SameUpperLowerLimit(t *testing.T) {
+	minReplicas := uint64(5)
+	maxReplicas := uint64(5)
+	scalingFactor := uint64(10)
+
+	got := CalculateReplicas("firing", minReplicas, minReplicas, maxReplicas, scalingFactor)
+
+	want := minReplicas
+	if want != got {
+		t.Logf("Replicas - want: %d, got: %d", want, got)
 		t.Fail()
 	}
 }
@@ -43,58 +46,62 @@ func TestScalingWithSameUpperLowerLimit(t *testing.T) {
 func TestMaxScale(t *testing.T) {
 	minReplicas := uint64(1)
 	scalingFactor := uint64(100)
-	newReplicas := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 20 {
-		t.Log("Expected ceiling of 20 replicas")
-		t.Fail()
+	got := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas*2, minReplicas, scalingFactor)
+	if got != scaling.DefaultMaxReplicas {
+		t.Fatalf("want ceiling: %d, but got: %d", scaling.DefaultMaxReplicas, got)
 	}
 }
 
-func TestInitialScale(t *testing.T) {
+func TestInitialScale_From1_Factor10(t *testing.T) {
 	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	newReplicas := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 5 {
-		t.Log("Expected the increment to equal 5")
-		t.Fail()
+	scalingFactor := uint64(10)
+	got := CalculateReplicas("firing", scaling.DefaultMinReplicas, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+	want := uint64(2)
+
+	if got != want {
+		t.Fatalf("want: %d, but got: %d", want, got)
 	}
 }
 
-func TestScale(t *testing.T) {
+func TestScale_midrange_factor25(t *testing.T) {
 	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	newReplicas := CalculateReplicas("firing", 4, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 8 {
-		t.Log("Expected newReplicas to equal 8")
-		t.Fail()
+	scalingFactor := uint64(25)
+	current := uint64(4)
+	maxReplicas := uint64(scaling.DefaultMaxReplicas)
+
+	got := CalculateReplicas("firing", current, maxReplicas, minReplicas, scalingFactor)
+	want := uint64(5)
+	if want != got {
+		t.Fatalf("want: %d, but got: %d", want, got)
 	}
 }
 
-func TestScaleCeiling(t *testing.T) {
+func TestScale_Ceiling_IsDefaultMaxReplicas(t *testing.T) {
 	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	newReplicas := CalculateReplicas("firing", 20, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 20 {
-		t.Log("Expected ceiling of 20 replicas")
-		t.Fail()
+	scalingFactor := uint64(10)
+	current := uint64(scaling.DefaultMaxReplicas)
+
+	got := CalculateReplicas("firing", current, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+	if got != scaling.DefaultMaxReplicas {
+		t.Fatalf("want: %d, but got: %d", scaling.DefaultMaxReplicas, got)
 	}
 }
 
-func TestScaleCeilingEdge(t *testing.T) {
+func TestScaleCeilingReplicasOver(t *testing.T) {
 	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	newReplicas := CalculateReplicas("firing", 19, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 20 {
-		t.Log("Expected ceiling of 20 replicas")
-		t.Fail()
+	scalingFactor := uint64(10)
+	got := CalculateReplicas("firing", 19, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+
+	if got != scaling.DefaultMaxReplicas {
+		t.Fatalf("want: %d, but got: %d", scaling.DefaultMaxReplicas, got)
 	}
 }
 
 func TestBackingOff(t *testing.T) {
 	minReplicas := uint64(1)
-	scalingFactor := uint64(20)
-	newReplicas := CalculateReplicas("resolved", 8, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
-	if newReplicas != 1 {
+	scalingFactor := uint64(10)
+	got := CalculateReplicas("resolved", 8, scaling.DefaultMaxReplicas, minReplicas, scalingFactor)
+	if got != 1 {
 		t.Log("Expected backing off to 1 replica")
 		t.Fail()
 	}
@@ -104,9 +111,9 @@ func TestScaledUpFrom1(t *testing.T) {
 	currentReplicas := uint64(1)
 	maxReplicas := uint64(5)
 	scalingFactor := uint64(30)
-	newReplicas := CalculateReplicas("firing", currentReplicas, maxReplicas, scaling.DefaultMinReplicas, scalingFactor)
-	if newReplicas <= currentReplicas {
-		t.Log("Expected newReplicas > currentReplica")
+	got := CalculateReplicas("firing", currentReplicas, maxReplicas, scaling.DefaultMinReplicas, scalingFactor)
+	if got <= currentReplicas {
+		t.Log("Expected got > currentReplica")
 		t.Fail()
 	}
 }
@@ -115,9 +122,9 @@ func TestScaledUpWithSmallParam(t *testing.T) {
 	currentReplicas := uint64(1)
 	maxReplicas := uint64(4)
 	scalingFactor := uint64(1)
-	newReplicas := CalculateReplicas("firing", currentReplicas, maxReplicas, scaling.DefaultMinReplicas, scalingFactor)
-	if newReplicas <= currentReplicas {
-		t.Log("Expected newReplicas > currentReplica")
+	got := CalculateReplicas("firing", currentReplicas, maxReplicas, scaling.DefaultMinReplicas, scalingFactor)
+	if got <= currentReplicas {
+		t.Log("Expected got > currentReplica")
 		t.Fail()
 	}
 }

gateway/plugin/external.go

@@ -7,7 +7,7 @@ import (
 	"bytes"
 	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"net"
 	"net/http"
@@ -89,7 +89,7 @@ func (s ExternalServiceQuery) GetReplicas(serviceName, serviceNamespace string)
 
 	var bytesOut []byte
 	if res.Body != nil {
-		bytesOut, _ = ioutil.ReadAll(res.Body)
+		bytesOut, _ = io.ReadAll(res.Body)
 		defer res.Body.Close()
 	}
 
@@ -111,20 +111,17 @@ func (s ExternalServiceQuery) GetReplicas(serviceName, serviceNamespace string)
 	scalingFactor := uint64(scaling.DefaultScalingFactor)
 	availableReplicas := function.AvailableReplicas
 
-	targetLoad := uint64(scaling.DefaultTargetLoad)
-
 	if function.Labels != nil {
 		labels := *function.Labels
 
 		minReplicas = extractLabelValue(labels[scaling.MinScaleLabel], minReplicas)
 		maxReplicas = extractLabelValue(labels[scaling.MaxScaleLabel], maxReplicas)
 		extractedScalingFactor := extractLabelValue(labels[scaling.ScalingFactorLabel], scalingFactor)
-		targetLoad = extractLabelValue(labels[scaling.TargetLoadLabel], targetLoad)
 
-		if extractedScalingFactor >= 0 && extractedScalingFactor <= 100 {
+		if extractedScalingFactor > 0 && extractedScalingFactor <= 100 {
 			scalingFactor = extractedScalingFactor
 		} else {
-			log.Printf("Bad Scaling Factor: %d, is not in range of [0 - 100]. Will fallback to %d", extractedScalingFactor, scalingFactor)
+			return scaling.ServiceQueryResponse{}, fmt.Errorf("bad scaling factor: %d, is not in range of [0 - 100]", extractedScalingFactor)
 		}
 	}
 
@@ -135,7 +132,6 @@ func (s ExternalServiceQuery) GetReplicas(serviceName, serviceNamespace string)
 		ScalingFactor:     scalingFactor,
 		AvailableReplicas: availableReplicas,
 		Annotations:       function.Annotations,
-		TargetLoad:        targetLoad,
 	}, err
 }
 

gateway/plugin/external_test.go

@@ -75,7 +75,6 @@ func TestGetReplicasExistentFn(t *testing.T) {
 		MinReplicas:       uint64(scaling.DefaultMinReplicas),
 		ScalingFactor:     uint64(scaling.DefaultScalingFactor),
 		AvailableReplicas: 0,
-		TargetLoad:        10,
 	}
 
 	var injector middleware.AuthInjector

gateway/scaling/ranges.go

@@ -5,13 +5,10 @@ const (
 	DefaultMinReplicas = 1
 
 	// DefaultMaxReplicas is the amount of replicas a service will auto-scale up to.
-	DefaultMaxReplicas = 20
+	DefaultMaxReplicas = 5
 
 	// DefaultScalingFactor is the defining proportion for the scaling increments.
-	DefaultScalingFactor = 20
-
-	// DefaultTargetLoad
-	DefaultTargetLoad = 10
+	DefaultScalingFactor = 10
 
 	DefaultTypeScale = "rps"
 
@@ -23,10 +20,4 @@ const (
 
 	// ScalingFactorLabel label indicates the scaling factor for a function
 	ScalingFactorLabel = "com.openfaas.scale.factor"
-
-	// TargetLoadLabel see also DefaultTargetScale
-	TargetLoadLabel = "com.openfaas.scale.target"
-
-	// ScaleTypeLabel see also DefaultScaleType
-	ScaleTypeLabel = "com.openfaas.scale.type"
 )

gateway/scaling/service_query.go

@@ -17,5 +17,4 @@ type ServiceQueryResponse struct {
 	ScalingFactor     uint64
 	AvailableReplicas uint64
 	Annotations       *map[string]string
-	TargetLoad        uint64
 }