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Merge pull request #24569 from williamsandrew/elb-proxy-protocol
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AWS: ELB proxy protocol support via annotation service.beta.kubernetes.io/aws-load-balancer-proxy-protocol

This is a ~~work in progress~~ branch that adds support for the Proxy Protocol with Elastic Load Balancers. The proxy protocol is documented here: http://www.haproxy.org/download/1.5/doc/proxy-protocol.txt. It allows us to pass the "real ip" address of a client to pods behind services.

As it stands now, we create an ELB policy on the load balancer that enables the proxy protocol. We then enumerate each node port assigned to the load balancer and add our newly created policy to it. The manual process is documented here: http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/enable-proxy-protocol.html


Right now, I’m looking to get some feedback on the approach before I dive too much deeper in the code. More precisely, I have questions regarding the following:

1) Right now I just check that a certain annotation exists on the service regardless of what its value is. Assuming we’re going to enable this feature via an annotation, what is the expected experience? This decision likely depends on the answers to the next questions.

2) Right now the implementation enables the proxy protocol on every ELB backend. The actual ELB API expects you to add the policy for each configured backend. Do we want the ability to configure the proxy protocol on a per service port basis? For example, if a service exposes TCP 80 and 443, would we want the ability to only enable the proxy protocol on port 443? Does this overcomplicate the implementation? If we wanted to go this direction we could do something like ...

```
{
  "service.beta.kubernetes.io/aws-load-balancer-proxy-protocol": "tcp:80,tcp:443"
}
```

3) I avoided this because I was concerned with scope creep and our organization doesn’t need it, but could/should our implementation be adjusted to just handle ELB policies in general? I hadn’t used the ELB API until I started working on this branch so I don’t know how realistic this is. I also don't know how common this use case is as our organization has used our own load balancing setup prior to Kubernetes. This page has a couple of examples at the bottom: http://docs.aws.amazon.com/cli/latest/reference/elb/create-load-balancer-policy.html

cc @justinsb

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k8s-merge-robot committed May 31, 2016
2 parents 561b938 + 01d9cdd commit 52cc96d
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Showing 3 changed files with 198 additions and 2 deletions.
27 changes: 26 additions & 1 deletion pkg/cloudprovider/providers/aws/aws.go
Original file line number Diff line number Diff line change
Expand Up @@ -69,6 +69,11 @@ const TagNameSubnetPublicELB = "kubernetes.io/role/elb"
// This lets us define more advanced semantics in future.
const ServiceAnnotationLoadBalancerInternal = "service.beta.kubernetes.io/aws-load-balancer-internal"

// Annotation used on the service to enable the proxy protocol on an ELB. Right now we only
// accept the value "*" which means enable the proxy protocol on all ELB backends. In the
// future we could adjust this to allow setting the proxy protocol only on certain backends.
const ServiceAnnotationLoadBalancerProxyProtocol = "service.beta.kubernetes.io/aws-load-balancer-proxy-protocol"

// Service annotation requesting a secure listener. Value is a valid certificate ARN.
// For more, see http://docs.aws.amazon.com/ElasticLoadBalancing/latest/DeveloperGuide/elb-listener-config.html
// CertARN is an IAM or CM certificate ARN, e.g. arn:aws:acm:us-east-1:123456789012:certificate/12345678-1234-1234-1234-123456789012
Expand Down Expand Up @@ -159,6 +164,8 @@ type ELB interface {
DescribeLoadBalancers(*elb.DescribeLoadBalancersInput) (*elb.DescribeLoadBalancersOutput, error)
RegisterInstancesWithLoadBalancer(*elb.RegisterInstancesWithLoadBalancerInput) (*elb.RegisterInstancesWithLoadBalancerOutput, error)
DeregisterInstancesFromLoadBalancer(*elb.DeregisterInstancesFromLoadBalancerInput) (*elb.DeregisterInstancesFromLoadBalancerOutput, error)
CreateLoadBalancerPolicy(*elb.CreateLoadBalancerPolicyInput) (*elb.CreateLoadBalancerPolicyOutput, error)
SetLoadBalancerPoliciesForBackendServer(*elb.SetLoadBalancerPoliciesForBackendServerInput) (*elb.SetLoadBalancerPoliciesForBackendServerOutput, error)

DetachLoadBalancerFromSubnets(*elb.DetachLoadBalancerFromSubnetsInput) (*elb.DetachLoadBalancerFromSubnetsOutput, error)
AttachLoadBalancerToSubnets(*elb.AttachLoadBalancerToSubnetsInput) (*elb.AttachLoadBalancerToSubnetsOutput, error)
Expand Down Expand Up @@ -2178,6 +2185,16 @@ func (s *AWSCloud) EnsureLoadBalancer(apiService *api.Service, hosts []string) (
internalELB = true
}

// Determine if we need to set the Proxy protocol policy
proxyProtocol := false
proxyProtocolAnnotation := apiService.Annotations[ServiceAnnotationLoadBalancerProxyProtocol]
if proxyProtocolAnnotation != "" {
if proxyProtocolAnnotation != "*" {
return nil, fmt.Errorf("annotation %q=%q detected, but the only value supported currently is '*'", ServiceAnnotationLoadBalancerProxyProtocol, proxyProtocolAnnotation)
}
proxyProtocol = true
}

// Find the subnets that the ELB will live in
subnetIDs, err := s.findELBSubnets(internalELB)
if err != nil {
Expand Down Expand Up @@ -2230,7 +2247,15 @@ func (s *AWSCloud) EnsureLoadBalancer(apiService *api.Service, hosts []string) (
securityGroupIDs := []string{securityGroupID}

// Build the load balancer itself
loadBalancer, err := s.ensureLoadBalancer(serviceName, loadBalancerName, listeners, subnetIDs, securityGroupIDs, internalELB)
loadBalancer, err := s.ensureLoadBalancer(
serviceName,
loadBalancerName,
listeners,
subnetIDs,
securityGroupIDs,
internalELB,
proxyProtocol,
)
if err != nil {
return nil, err
}
Expand Down
137 changes: 136 additions & 1 deletion pkg/cloudprovider/providers/aws/aws_loadbalancer.go
Original file line number Diff line number Diff line change
Expand Up @@ -28,7 +28,9 @@ import (
"k8s.io/kubernetes/pkg/util/sets"
)

func (s *AWSCloud) ensureLoadBalancer(namespacedName types.NamespacedName, loadBalancerName string, listeners []*elb.Listener, subnetIDs []string, securityGroupIDs []string, internalELB bool) (*elb.LoadBalancerDescription, error) {
const ProxyProtocolPolicyName = "k8s-proxyprotocol-enabled"

func (s *AWSCloud) ensureLoadBalancer(namespacedName types.NamespacedName, loadBalancerName string, listeners []*elb.Listener, subnetIDs []string, securityGroupIDs []string, internalELB, proxyProtocol bool) (*elb.LoadBalancerDescription, error) {
loadBalancer, err := s.describeLoadBalancer(loadBalancerName)
if err != nil {
return nil, err
Expand Down Expand Up @@ -62,6 +64,22 @@ func (s *AWSCloud) ensureLoadBalancer(namespacedName types.NamespacedName, loadB
if err != nil {
return nil, err
}

if proxyProtocol {
err = s.createProxyProtocolPolicy(loadBalancerName)
if err != nil {
return nil, err
}

for _, listener := range listeners {
glog.V(2).Infof("Adjusting AWS loadbalancer proxy protocol on node port %d. Setting to true", *listener.InstancePort)
err := s.setBackendPolicies(loadBalancerName, *listener.InstancePort, []*string{aws.String(ProxyProtocolPolicyName)})
if err != nil {
return nil, err
}
}
}

dirty = true
} else {
// TODO: Sync internal vs non-internal
Expand Down Expand Up @@ -189,6 +207,73 @@ func (s *AWSCloud) ensureLoadBalancer(namespacedName types.NamespacedName, loadB
dirty = true
}
}

{
// Sync proxy protocol state for new and existing listeners

proxyPolicies := make([]*string, 0)
if proxyProtocol {
// Ensure the backend policy exists

// NOTE The documentation for the AWS API indicates we could get an HTTP 400
// back if a policy of the same name already exists. However, the aws-sdk does not
// seem to return an error to us in these cases. Therefore this will issue an API
// request everytime.
err := s.createProxyProtocolPolicy(loadBalancerName)
if err != nil {
return nil, err
}

proxyPolicies = append(proxyPolicies, aws.String(ProxyProtocolPolicyName))
}

foundBackends := make(map[int64]bool)
proxyProtocolBackends := make(map[int64]bool)
for _, backendListener := range loadBalancer.BackendServerDescriptions {
foundBackends[*backendListener.InstancePort] = false
proxyProtocolBackends[*backendListener.InstancePort] = proxyProtocolEnabled(backendListener)
}

for _, listener := range listeners {
setPolicy := false
instancePort := *listener.InstancePort

if currentState, ok := proxyProtocolBackends[instancePort]; !ok {
// This is a new ELB backend so we only need to worry about
// potentientally adding a policy and not removing an
// existing one
setPolicy = proxyProtocol
} else {
foundBackends[instancePort] = true
// This is an existing ELB backend so we need to determine
// if the state changed
setPolicy = (currentState != proxyProtocol)
}

if setPolicy {
glog.V(2).Infof("Adjusting AWS loadbalancer proxy protocol on node port %d. Setting to %t", instancePort, proxyProtocol)
err := s.setBackendPolicies(loadBalancerName, instancePort, proxyPolicies)
if err != nil {
return nil, err
}
dirty = true
}
}

// We now need to figure out if any backend policies need removed
// because these old policies will stick around even if there is no
// corresponding listener anymore
for instancePort, found := range foundBackends {
if !found {
glog.V(2).Infof("Adjusting AWS loadbalancer proxy protocol on node port %d. Setting to false", instancePort)
err := s.setBackendPolicies(loadBalancerName, instancePort, []*string{})
if err != nil {
return nil, err
}
dirty = true
}
}
}
}

if dirty {
Expand Down Expand Up @@ -308,3 +393,53 @@ func (s *AWSCloud) ensureLoadBalancerInstances(loadBalancerName string, lbInstan

return nil
}

func (s *AWSCloud) createProxyProtocolPolicy(loadBalancerName string) error {
request := &elb.CreateLoadBalancerPolicyInput{
LoadBalancerName: aws.String(loadBalancerName),
PolicyName: aws.String(ProxyProtocolPolicyName),
PolicyTypeName: aws.String("ProxyProtocolPolicyType"),
PolicyAttributes: []*elb.PolicyAttribute{
{
AttributeName: aws.String("ProxyProtocol"),
AttributeValue: aws.String("true"),
},
},
}
glog.V(2).Info("Creating proxy protocol policy on load balancer")
_, err := s.elb.CreateLoadBalancerPolicy(request)
if err != nil {
return fmt.Errorf("error creating proxy protocol policy on load balancer: %v", err)
}

return nil
}

func (s *AWSCloud) setBackendPolicies(loadBalancerName string, instancePort int64, policies []*string) error {
request := &elb.SetLoadBalancerPoliciesForBackendServerInput{
InstancePort: aws.Int64(instancePort),
LoadBalancerName: aws.String(loadBalancerName),
PolicyNames: policies,
}
if len(policies) > 0 {
glog.V(2).Infof("Adding AWS loadbalancer backend policies on node port %d", instancePort)
} else {
glog.V(2).Infof("Removing AWS loadbalancer backend policies on node port %d", instancePort)
}
_, err := s.elb.SetLoadBalancerPoliciesForBackendServer(request)
if err != nil {
return fmt.Errorf("error adjusting AWS loadbalancer backend policies: %v", err)
}

return nil
}

func proxyProtocolEnabled(backend *elb.BackendServerDescription) bool {
for _, policy := range backend.PolicyNames {
if aws.StringValue(policy) == ProxyProtocolPolicyName {
return true
}
}

return false
}
36 changes: 36 additions & 0 deletions pkg/cloudprovider/providers/aws/aws_test.go
Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ import (
"github.com/golang/glog"
"k8s.io/kubernetes/pkg/api"
"k8s.io/kubernetes/pkg/api/unversioned"
"k8s.io/kubernetes/pkg/util/sets"

"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/mock"
Expand Down Expand Up @@ -487,6 +488,14 @@ func (elb *FakeELB) ConfigureHealthCheck(*elb.ConfigureHealthCheckInput) (*elb.C
panic("Not implemented")
}

func (elb *FakeELB) CreateLoadBalancerPolicy(*elb.CreateLoadBalancerPolicyInput) (*elb.CreateLoadBalancerPolicyOutput, error) {
panic("Not implemented")
}

func (elb *FakeELB) SetLoadBalancerPoliciesForBackendServer(*elb.SetLoadBalancerPoliciesForBackendServerInput) (*elb.SetLoadBalancerPoliciesForBackendServerOutput, error) {
panic("Not implemented")
}

type FakeASG struct {
aws *FakeAWSServices
}
Expand Down Expand Up @@ -1302,3 +1311,30 @@ func TestBuildListener(t *testing.T) {
}
}
}

func TestProxyProtocolEnabled(t *testing.T) {
policies := sets.NewString(ProxyProtocolPolicyName, "FooBarFoo")
fakeBackend := &elb.BackendServerDescription{
InstancePort: aws.Int64(80),
PolicyNames: stringSetToPointers(policies),
}
result := proxyProtocolEnabled(fakeBackend)
assert.True(t, result, "expected to find %s in %s", ProxyProtocolPolicyName, policies)

policies = sets.NewString("FooBarFoo")
fakeBackend = &elb.BackendServerDescription{
InstancePort: aws.Int64(80),
PolicyNames: []*string{
aws.String("FooBarFoo"),
},
}
result = proxyProtocolEnabled(fakeBackend)
assert.False(t, result, "did not expect to find %s in %s", ProxyProtocolPolicyName, policies)

policies = sets.NewString()
fakeBackend = &elb.BackendServerDescription{
InstancePort: aws.Int64(80),
}
result = proxyProtocolEnabled(fakeBackend)
assert.False(t, result, "did not expect to find %s in %s", ProxyProtocolPolicyName, policies)
}

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