loadbalancer.go

/*
Copyright 2018 The Kubernetes Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package elb

import (
	"fmt"
	"reflect"
	"time"

	"github.com/aws/aws-sdk-go/aws"
	"github.com/aws/aws-sdk-go/aws/awserr"
	"github.com/aws/aws-sdk-go/service/elb"
	"github.com/pkg/errors"
	"sigs.k8s.io/cluster-api-provider-aws/pkg/apis/awsprovider/v1alpha1"
	"sigs.k8s.io/cluster-api-provider-aws/pkg/cloud/aws/converters"
	"sigs.k8s.io/cluster-api-provider-aws/pkg/cloud/aws/services/awserrors"
	"sigs.k8s.io/cluster-api-provider-aws/pkg/cloud/aws/services/wait"
)

// ReconcileLoadbalancers reconciles the load balancers for the given cluster.
func (s *Service) ReconcileLoadbalancers() error {
	s.scope.V(2).Info("Reconciling load balancers")

	// Get default api server spec.
	spec := s.getAPIServerClassicELBSpec()

	// Describe or create.
	apiELB, err := s.describeClassicELB(spec.Name)
	if IsNotFound(err) {
		apiELB, err = s.createClassicELB(spec)
		if err != nil {
			return err
		}

		s.scope.V(2).Info("Created new classic load balancer for apiserver", "api-server-elb-name", apiELB.Name)
	} else if err != nil {
		return err
	}

	if !reflect.DeepEqual(spec.Attributes, apiELB.Attributes) {
		err := s.configureAttributes(apiELB.Name, spec.Attributes)
		if err != nil {
			return err
		}
	}

	// TODO(vincepri): check if anything has changed and reconcile as necessary.
	apiELB.DeepCopyInto(&s.scope.Network().APIServerELB)
	s.scope.V(4).Info("Control plane load balancer", "api-server-elb", apiELB)

	s.scope.V(2).Info("Reconcile load balancers completed successfully")
	return nil
}

// GetAPIServerDNSName returns the DNS name endpoint for the API server
func (s *Service) GetAPIServerDNSName() (string, error) {
	apiELB, err := s.describeClassicELB(GenerateELBName(s.scope.Name(), v1alpha1.APIServerRoleTagValue))

	if err != nil {
		return "", err
	}

	return apiELB.DNSName, nil
}

// DeleteLoadbalancers deletes the load balancers for the given cluster.
func (s *Service) DeleteLoadbalancers() error {
	s.scope.V(2).Info("Deleting load balancers")

	// Get default api server name.
	elbName := GenerateELBName(s.scope.Name(), v1alpha1.APIServerRoleTagValue)

	// Describe and delete if exists.
	if _, err := s.describeClassicELB(elbName); err != nil {
		if IsNotFound(err) {
			return nil
		}
		return err
	}

	if err := s.deleteClassicELBAndWait(elbName); err != nil {
		return err
	}

	s.scope.V(2).Info("Deleting load balancers completed successfully")
	return nil
}

// RegisterInstanceWithClassicELB registers an instance with a classic ELB
func (s *Service) RegisterInstanceWithClassicELB(instanceID string, loadBalancer string) error {
	input := &elb.RegisterInstancesWithLoadBalancerInput{
		Instances:        []*elb.Instance{{InstanceId: aws.String(instanceID)}},
		LoadBalancerName: aws.String(loadBalancer),
	}

	_, err := s.scope.ELB.RegisterInstancesWithLoadBalancer(input)
	if err != nil {
		return err
	}

	return nil
}

// RegisterInstanceWithAPIServerELB registers an instance with a classic ELB
func (s *Service) RegisterInstanceWithAPIServerELB(instanceID string) error {
	input := &elb.RegisterInstancesWithLoadBalancerInput{
		Instances:        []*elb.Instance{{InstanceId: aws.String(instanceID)}},
		LoadBalancerName: aws.String(GenerateELBName(s.scope.Name(), v1alpha1.APIServerRoleTagValue)),
	}

	_, err := s.scope.ELB.RegisterInstancesWithLoadBalancer(input)
	if err != nil {
		return err
	}

	return nil
}

// GenerateELBName generates a formatted ELB name
func GenerateELBName(clusterName string, elbName string) string {
	return fmt.Sprintf("%s-%s", clusterName, elbName)
}

func (s *Service) getAPIServerClassicELBSpec() *v1alpha1.ClassicELB {
	res := &v1alpha1.ClassicELB{
		Name:   GenerateELBName(s.scope.Name(), v1alpha1.APIServerRoleTagValue),
		Scheme: v1alpha1.ClassicELBSchemeInternetFacing,
		Listeners: []*v1alpha1.ClassicELBListener{
			{
				Protocol:         v1alpha1.ClassicELBProtocolTCP,
				Port:             6443,
				InstanceProtocol: v1alpha1.ClassicELBProtocolTCP,
				InstancePort:     6443,
			},
		},
		HealthCheck: &v1alpha1.ClassicELBHealthCheck{
			Target:             fmt.Sprintf("%v:%d", v1alpha1.ClassicELBProtocolTCP, 6443),
			Interval:           10 * time.Second,
			Timeout:            5 * time.Second,
			HealthyThreshold:   5,
			UnhealthyThreshold: 3,
		},
		SecurityGroupIDs: []string{s.scope.SecurityGroups()[v1alpha1.SecurityGroupControlPlane].ID},
		Attributes: v1alpha1.ClassicELBAttributes{
			IdleTimeout: 10 * time.Minute,
		},
	}

	res.Tags = v1alpha1.Build(v1alpha1.BuildParams{
		ClusterName: s.scope.Name(),
		Lifecycle:   v1alpha1.ResourceLifecycleOwned,
		Role:        aws.String(v1alpha1.APIServerRoleTagValue),
	})

	for _, sn := range s.scope.Subnets().FilterPublic() {
		res.SubnetIDs = append(res.SubnetIDs, sn.ID)
	}

	return res
}

func (s *Service) createClassicELB(spec *v1alpha1.ClassicELB) (*v1alpha1.ClassicELB, error) {
	input := &elb.CreateLoadBalancerInput{
		LoadBalancerName: aws.String(spec.Name),
		Subnets:          aws.StringSlice(spec.SubnetIDs),
		SecurityGroups:   aws.StringSlice(spec.SecurityGroupIDs),
		Scheme:           aws.String(string(spec.Scheme)),
		Tags:             converters.MapToELBTags(spec.Tags),
	}

	for _, ln := range spec.Listeners {
		input.Listeners = append(input.Listeners, &elb.Listener{
			Protocol:         aws.String(string(ln.Protocol)),
			LoadBalancerPort: aws.Int64(ln.Port),
			InstanceProtocol: aws.String(string(ln.InstanceProtocol)),
			InstancePort:     aws.Int64(ln.InstancePort),
		})
	}

	out, err := s.scope.ELB.CreateLoadBalancer(input)
	if err != nil {
		return nil, errors.Wrapf(err, "failed to create classic load balancer: %v", spec)
	}

	if spec.HealthCheck != nil {
		hc := &elb.ConfigureHealthCheckInput{
			LoadBalancerName: aws.String(spec.Name),
			HealthCheck: &elb.HealthCheck{
				Target:             aws.String(spec.HealthCheck.Target),
				Interval:           aws.Int64(int64(spec.HealthCheck.Interval.Seconds())),
				Timeout:            aws.Int64(int64(spec.HealthCheck.Timeout.Seconds())),
				HealthyThreshold:   aws.Int64(spec.HealthCheck.HealthyThreshold),
				UnhealthyThreshold: aws.Int64(spec.HealthCheck.UnhealthyThreshold),
			},
		}

		if _, err := s.scope.ELB.ConfigureHealthCheck(hc); err != nil {
			return nil, errors.Wrapf(err, "failed to configure health check for classic load balancer: %v", spec)
		}
	}

	s.scope.V(2).Info("Created classic load balancer", "dns-name", *out.DNSName)

	res := spec.DeepCopy()
	res.DNSName = *out.DNSName
	return res, nil
}

func (s *Service) configureAttributes(name string, attributes v1alpha1.ClassicELBAttributes) error {
	attrs := &elb.ModifyLoadBalancerAttributesInput{
		LoadBalancerName:       aws.String(name),
		LoadBalancerAttributes: &elb.LoadBalancerAttributes{},
	}

	if attributes.IdleTimeout > 0 {
		attrs.LoadBalancerAttributes.ConnectionSettings = &elb.ConnectionSettings{
			IdleTimeout: aws.Int64(int64(attributes.IdleTimeout.Seconds())),
		}
	}

	if _, err := s.scope.ELB.ModifyLoadBalancerAttributes(attrs); err != nil {
		return errors.Wrapf(err, "failed to configure attributes for classic load balancer: %v", name)
	}

	return nil
}

func (s *Service) deleteClassicELB(name string) error {
	input := &elb.DeleteLoadBalancerInput{
		LoadBalancerName: aws.String(name),
	}

	if _, err := s.scope.ELB.DeleteLoadBalancer(input); err != nil {
		return err
	}
	return nil
}

func (s *Service) deleteClassicELBAndWait(name string) error {
	if err := s.deleteClassicELB(name); err != nil {
		return err
	}

	input := &elb.DescribeLoadBalancersInput{
		LoadBalancerNames: aws.StringSlice([]string{name}),
	}

	checkForELBDeletion := func() (done bool, err error) {
		out, err := s.scope.ELB.DescribeLoadBalancers(input)

		// ELB already deleted.
		if len(out.LoadBalancerDescriptions) == 0 {
			return true, nil
		}

		if code, _ := awserrors.Code(err); code == "LoadBalancerNotFound" {
			return true, nil
		}

		if err != nil {
			return false, err
		}

		return false, nil

	}

	if err := wait.WaitForWithRetryable(wait.NewBackoff(), checkForELBDeletion, []string{}); err != nil {
		return errors.Wrapf(err, "failed to wait for ELB deletion %q", name)
	}

	return nil
}

func (s *Service) describeClassicELB(name string) (*v1alpha1.ClassicELB, error) {
	input := &elb.DescribeLoadBalancersInput{
		LoadBalancerNames: aws.StringSlice([]string{name}),
	}

	out, err := s.scope.ELB.DescribeLoadBalancers(input)
	if err != nil {
		if aerr, ok := err.(awserr.Error); ok {
			switch aerr.Code() {
			case elb.ErrCodeAccessPointNotFoundException:
				return nil, errors.Wrapf(err, "no classic load balancer found with name: %q", name)
			case elb.ErrCodeDependencyThrottleException:
				return nil, errors.Wrap(err, "too many requests made to the ELB service")
			default:
				return nil, errors.Wrap(err, "unexpected aws error")
			}
		} else {
			return nil, errors.Wrapf(err, "failed to describe classic load balancer: %s", name)
		}
	}

	if out != nil && len(out.LoadBalancerDescriptions) == 0 {
		return nil, NewNotFound(fmt.Errorf("no classic load balancer found with name %q", name))
	}

	if s.scope.VPC().ID != "" && s.scope.VPC().ID != *out.LoadBalancerDescriptions[0].VPCId {
		return nil, errors.Errorf(
			"ELB names must be unique within a region: %q ELB already exists in this region in VPC %q",
			name, *out.LoadBalancerDescriptions[0].VPCId)
	}

	outAtt, err := s.scope.ELB.DescribeLoadBalancerAttributes(&elb.DescribeLoadBalancerAttributesInput{
		LoadBalancerName: aws.String(name),
	})

	if err != nil {
		return nil, errors.Wrapf(err, "failed to describe classic load balancer %q attributes", name)
	}

	return fromSDKTypeToClassicELB(out.LoadBalancerDescriptions[0], outAtt.LoadBalancerAttributes), nil
}

func fromSDKTypeToClassicELB(v *elb.LoadBalancerDescription, attrs *elb.LoadBalancerAttributes) *v1alpha1.ClassicELB {
	res := &v1alpha1.ClassicELB{
		Name:             aws.StringValue(v.LoadBalancerName),
		Scheme:           v1alpha1.ClassicELBScheme(*v.Scheme),
		SubnetIDs:        aws.StringValueSlice(v.Subnets),
		SecurityGroupIDs: aws.StringValueSlice(v.SecurityGroups),
		DNSName:          aws.StringValue(v.DNSName),
	}

	if attrs.ConnectionSettings != nil && attrs.ConnectionSettings.IdleTimeout != nil {
		res.Attributes.IdleTimeout = time.Duration(*attrs.ConnectionSettings.IdleTimeout) * time.Second
	}

	return res
}