Add fallback to fetch limits from EC2 API (#782)

(cherry picked from commit 3b0f876)

pkg/awsutils/awsutils.go

@@ -916,9 +916,25 @@ func (cache *EC2InstanceMetadataCache) GetENIipLimit() (int, error) {
 // GetENILimit returns the number of ENIs can be attached to an instance
 func (cache *EC2InstanceMetadataCache) GetENILimit() (int, error) {
 	eniLimit, ok := InstanceENIsAvailable[cache.instanceType]
-
 	if !ok {
-		return 0, errors.New(fmt.Sprintf("%s: %s", UnknownInstanceType, cache.instanceType))
+		// Fetch from EC2 API
+		describeInstanceTypesInput := &ec2.DescribeInstanceTypesInput{InstanceTypes: []*string{aws.String(cache.instanceType)}}
+		output, err := cache.ec2SVC.DescribeInstanceTypes(describeInstanceTypesInput)
+		if err != nil || len(output.InstanceTypes) != 1 {
+			log.Errorf("", err)
+			return 0, errors.New(fmt.Sprintf("Failed calling DescribeInstanceTypes for `%s`: %v", cache.instanceType, err))
+		}
+		info := output.InstanceTypes[0]
+		// Ignore any missing values
+		instanceType := aws.StringValue(info.InstanceType)
+		eniLimit = int(aws.Int64Value(info.NetworkInfo.MaximumNetworkInterfaces))
+		ipLimit := int(aws.Int64Value(info.NetworkInfo.Ipv4AddressesPerInterface))
+		if instanceType != "" && eniLimit > 0 && ipLimit > 0 {
+			InstanceENIsAvailable[instanceType] = eniLimit
+			InstanceIPsAvailable[instanceType] = ipLimit
+		} else {
+			return 0, errors.New(fmt.Sprintf("%s: %s", UnknownInstanceType, cache.instanceType))
+		}
 	}
 	return eniLimit, nil
 }

pkg/awsutils/awsutils_test.go

@@ -627,6 +627,27 @@ func TestFreeENIDescribeErr(t *testing.T) {
 	assert.Error(t, err)
 }
 
+func TestDescribeInstanceTypes(t *testing.T) {
+	ctrl, _, mockEC2 := setup(t)
+	defer ctrl.Finish()
+	mockEC2.EXPECT().DescribeInstanceTypes(gomock.Any()).Return(&ec2.DescribeInstanceTypesOutput{
+		InstanceTypes: []*ec2.InstanceTypeInfo{
+			{InstanceType: aws.String("not-there"), NetworkInfo: &ec2.NetworkInfo{
+				MaximumNetworkInterfaces:  aws.Int64(9),
+				Ipv4AddressesPerInterface: aws.Int64(99)},
+			},
+		},
+		NextToken: nil,
+	}, nil)
+
+	ins := &EC2InstanceMetadataCache{ec2SVC: mockEC2}
+	ins.instanceType = "not-there"
+	value, err := ins.GetENILimit()
+	assert.NoError(t, err)
+	assert.Equal(t, 9, value)
+	assert.Equal(t, 99, InstanceIPsAvailable[ins.instanceType])
+}
+
 func TestAllocIPAddress(t *testing.T) {
 	ctrl, _, mockEC2 := setup(t)
 	defer ctrl.Finish()

pkg/awsutils/gen_vpc_ip_limits.go

@@ -49,11 +49,11 @@ func main() {
 		log.Fatal(err)
 	}
 	svc := ec2.New(sess)
-	describeInstanceTypeInput := &ec2.DescribeInstanceTypesInput{}
+	describeInstanceTypesInput := &ec2.DescribeInstanceTypesInput{}
 
 	eniLimitMap := make(map[string]ENILimit)
 	for {
-		output, err := svc.DescribeInstanceTypes(describeInstanceTypeInput)
+		output, err := svc.DescribeInstanceTypes(describeInstanceTypesInput)
 		if err != nil {
 			log.Fatal(err)
 		}
@@ -71,7 +71,7 @@ func main() {
 		if output.NextToken == nil {
 			break
 		}
-		describeInstanceTypeInput = &ec2.DescribeInstanceTypesInput{
+		describeInstanceTypesInput = &ec2.DescribeInstanceTypesInput{
 			NextToken: output.NextToken,
 		}
 	}

pkg/ec2wrapper/client.go

@@ -23,6 +23,7 @@ import (
 type EC2 interface {
 	CreateNetworkInterface(input *ec2svc.CreateNetworkInterfaceInput) (*ec2svc.CreateNetworkInterfaceOutput, error)
 	DescribeInstances(input *ec2svc.DescribeInstancesInput) (*ec2svc.DescribeInstancesOutput, error)
+	DescribeInstanceTypes(input *ec2svc.DescribeInstanceTypesInput) (*ec2svc.DescribeInstanceTypesOutput, error)
 	AttachNetworkInterface(input *ec2svc.AttachNetworkInterfaceInput) (*ec2svc.AttachNetworkInterfaceOutput, error)
 	DeleteNetworkInterface(input *ec2svc.DeleteNetworkInterfaceInput) (*ec2svc.DeleteNetworkInterfaceOutput, error)
 	DetachNetworkInterface(input *ec2svc.DetachNetworkInterfaceInput) (*ec2svc.DetachNetworkInterfaceOutput, error)