Fix/pay per request billing mode (#55)

Issue 1595:
[[dynamodb] Status always false when setting billingMode to PAY_PER_REQUEST](aws-controllers-k8s/community#1595)

Description of changes:
Before comparing the desire and latest status, set ProvisionedThroughput to nil(another way is to set write/readCapacityUnits to 0)  when billing mode is `PAY_PER_REQUEST`.  

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.

Author: Julian-Chu

pkg/resource/table/hooks.go

@@ -24,6 +24,7 @@ import (
 	ackrequeue "github.com/aws-controllers-k8s/runtime/pkg/requeue"
 	ackrtlog "github.com/aws-controllers-k8s/runtime/pkg/runtime/log"
 	ackutil "github.com/aws-controllers-k8s/runtime/pkg/util"
+	"github.com/aws/aws-sdk-go/aws"
 	svcsdk "github.com/aws/aws-sdk-go/service/dynamodb"
 	corev1 "k8s.io/api/core/v1"
 
@@ -418,9 +419,17 @@ func customPreCompare(
 	a *resource,
 	b *resource,
 ) {
-	// TODO(hilalymh): customDeltaFunctions for AttributeDefintions
+	// TODO(hilalymh): customDeltaFunctions for AttributeDefinitions
 	// TODO(hilalymh): customDeltaFunctions for GlobalSecondaryIndexes
 
+	// See https://github.com/aws-controllers-k8s/community/issues/1595
+	if aws.StringValue(a.ko.Spec.BillingMode) == string(v1alpha1.BillingMode_PAY_PER_REQUEST) {
+		a.ko.Spec.ProvisionedThroughput = nil
+	}
+	if aws.StringValue(b.ko.Spec.BillingMode) == string(v1alpha1.BillingMode_PAY_PER_REQUEST) {
+		b.ko.Spec.ProvisionedThroughput = nil
+	}
+
 	if len(a.ko.Spec.Tags) != len(b.ko.Spec.Tags) {
 		delta.Add("Spec.Tags", a.ko.Spec.Tags, b.ko.Spec.Tags)
 	} else if a.ko.Spec.Tags != nil && b.ko.Spec.Tags != nil {

pkg/resource/table/hooks_test.go

@@ -17,6 +17,7 @@ import (
 	"reflect"
 	"testing"
 
+	"github.com/aws-controllers-k8s/runtime/pkg/compare"
 	"github.com/aws/aws-sdk-go/aws"
 
 	"github.com/aws-controllers-k8s/dynamodb-controller/apis/v1alpha1"
@@ -130,3 +131,30 @@ func Test_computeTagsDelta(t *testing.T) {
 		})
 	}
 }
+
+func Test_customPreCompare(t *testing.T) {
+	t.Run("when billing mode is PAY_PER_REQUEST, ProvisionedThroughput should be nil", func(t *testing.T) {
+		a := &resource{ko: &v1alpha1.Table{
+			Spec: v1alpha1.TableSpec{
+				BillingMode:           aws.String(string(v1alpha1.BillingMode_PAY_PER_REQUEST)),
+				ProvisionedThroughput: &v1alpha1.ProvisionedThroughput{},
+			},
+		}}
+
+		b := &resource{ko: &v1alpha1.Table{
+			Spec: v1alpha1.TableSpec{
+				BillingMode:           aws.String(string(v1alpha1.BillingMode_PAY_PER_REQUEST)),
+				ProvisionedThroughput: &v1alpha1.ProvisionedThroughput{},
+			},
+		}}
+		delta := &compare.Delta{}
+		customPreCompare(delta, a, b)
+		if a.ko.Spec.ProvisionedThroughput != nil {
+			t.Errorf("a.Spec.ProvisionedThroughput should be nil, but got %+v", a.ko.Spec.ProvisionedThroughput)
+		}
+
+		if b.ko.Spec.ProvisionedThroughput != nil {
+			t.Errorf("b.Spec.ProvisionedThroughput should be nil, but got %+v", a.ko.Spec.ProvisionedThroughput)
+		}
+	})
+}