Add `Targets` field to service resolver failovers. (#14162)

This field will be used for cluster peering failover.

.changelog/14162.txt

@@ -0,0 +1,5 @@
+```release-note:improvement
+config-entry: Validate that service-resolver `Failover`s and `Redirect`s only
+specify `Partition` and `Namespace` on Consul Enterprise. This prevents scenarios
+where OSS Consul would save service-resolvers that require Consul Enterprise.
+```

agent/structs/config_entry_discoverychain.go

@@ -954,6 +954,10 @@ func (e *ServiceResolverConfigEntry) Validate() error {
 
 		r := e.Redirect
 
+		if err := r.ValidateEnterprise(); err != nil {
+			return fmt.Errorf("Redirect: %s", err.Error())
+		}
+
 		if len(e.Failover) > 0 {
 			return fmt.Errorf("Redirect and Failover cannot both be set")
 		}
@@ -988,18 +992,59 @@ func (e *ServiceResolverConfigEntry) Validate() error {
 				return fmt.Errorf("Cross-datacenter failover is only supported in the default partition")
 			}
 
-			if subset != "*" && !isSubset(subset) {
-				return fmt.Errorf("Bad Failover[%q]: not a valid subset", subset)
+			errorPrefix := fmt.Sprintf("Bad Failover[%q]: ", subset)
+
+			if err := f.ValidateEnterprise(); err != nil {
+				return fmt.Errorf(errorPrefix + err.Error())
 			}
 
-			if f.Service == "" && f.ServiceSubset == "" && f.Namespace == "" && len(f.Datacenters) == 0 {
-				return fmt.Errorf("Bad Failover[%q] one of Service, ServiceSubset, Namespace, or Datacenters is required", subset)
+			if subset != "*" && !isSubset(subset) {
+				return fmt.Errorf(errorPrefix + "not a valid subset subset")
+			}
+
+			if f.isEmpty() {
+				return fmt.Errorf(errorPrefix + "one of Service, ServiceSubset, Namespace, Targets, or Datacenters is required")
 			}
 
 			if f.ServiceSubset != "" {
 				if f.Service == "" || f.Service == e.Name {
 					if !isSubset(f.ServiceSubset) {
-						return fmt.Errorf("Bad Failover[%q].ServiceSubset %q is not a valid subset of %q", subset, f.ServiceSubset, f.Service)
+						return fmt.Errorf("%sServiceSubset %q is not a valid subset of %q", errorPrefix, f.ServiceSubset, f.Service)
+					}
+				}
+			}
+
+			if len(f.Datacenters) != 0 && len(f.Targets) != 0 {
+				return fmt.Errorf("Bad Failover[%q]: Targets cannot be set with Datacenters", subset)
+			}
+
+			if f.ServiceSubset != "" && len(f.Targets) != 0 {
+				return fmt.Errorf("Bad Failover[%q]: Targets cannot be set with ServiceSubset", subset)
+			}
+
+			if f.Service != "" && len(f.Targets) != 0 {
+				return fmt.Errorf("Bad Failover[%q]: Targets cannot be set with Service", subset)
+			}
+
+			for i, target := range f.Targets {
+				errorPrefix := fmt.Sprintf("Bad Failover[%q].Targets[%d]: ", subset, i)
+
+				if err := target.ValidateEnterprise(); err != nil {
+					return fmt.Errorf(errorPrefix + err.Error())
+				}
+
+				switch {
+				case target.Peer != "" && target.ServiceSubset != "":
+					return fmt.Errorf(errorPrefix + "Peer cannot be set with ServiceSubset")
+				case target.Peer != "" && target.Partition != "":
+					return fmt.Errorf(errorPrefix + "Partition cannot be set with Peer")
+				case target.Peer != "" && target.Datacenter != "":
+					return fmt.Errorf(errorPrefix + "Peer cannot be set with Datacenter")
+				case target.Partition != "" && target.Datacenter != "":
+					return fmt.Errorf(errorPrefix + "Partition cannot be set with Datacenter")
+				case target.ServiceSubset != "" && (target.Service == "" || target.Service == e.Name):
+					if !isSubset(target.ServiceSubset) {
+						return fmt.Errorf("%sServiceSubset %q is not a valid subset of %q", errorPrefix, target.ServiceSubset, e.Name)
 					}
 				}
 			}
@@ -1107,9 +1152,24 @@ func (e *ServiceResolverConfigEntry) ListRelatedServices() []ServiceID {
 
 	if len(e.Failover) > 0 {
 		for _, failover := range e.Failover {
-			failoverID := NewServiceID(defaultIfEmpty(failover.Service, e.Name), failover.GetEnterpriseMeta(&e.EnterpriseMeta))
-			if failoverID != svcID {
-				found[failoverID] = struct{}{}
+			if len(failover.Targets) == 0 {
+				failoverID := NewServiceID(defaultIfEmpty(failover.Service, e.Name), failover.GetEnterpriseMeta(&e.EnterpriseMeta))
+				if failoverID != svcID {
+					found[failoverID] = struct{}{}
+				}
+				continue
+			}
+
+			for _, target := range failover.Targets {
+				// We can't know about related services on cluster peers.
+				if target.Peer != "" {
+					continue
+				}
+
+				failoverID := NewServiceID(defaultIfEmpty(target.Service, e.Name), target.GetEnterpriseMeta(failover.GetEnterpriseMeta(&e.EnterpriseMeta)))
+				if failoverID != svcID {
+					found[failoverID] = struct{}{}
+				}
 			}
 		}
 	}
@@ -1175,8 +1235,9 @@ type ServiceResolverRedirect struct {
 
 // There are some restrictions on what is allowed in here:
 //
-// - Service, ServiceSubset, Namespace, and Datacenters cannot all be
-//   empty at once.
+// - Service, ServiceSubset, Namespace, Datacenters, and Targets cannot all be
+// empty at once. When Targets is defined, the other fields should not be
+// populated.
 //
 type ServiceResolverFailover struct {
 	// Service is the service to resolve instead of the default as the failover
@@ -1205,6 +1266,37 @@ type ServiceResolverFailover struct {
 	//
 	// This is a DESTINATION during failover.
 	Datacenters []string `json:",omitempty"`
+
+	// Targets specifies a fixed list of failover targets to try. We never try a
+	// target multiple times, so those are subtracted from this list before
+	// proceeding.
+	//
+	// This is a DESTINATION during failover.
+	Targets []ServiceResolverFailoverTarget `json:",omitempty"`
+}
+
+func (f *ServiceResolverFailover) isEmpty() bool {
+	return f.Service == "" && f.ServiceSubset == "" && f.Namespace == "" && len(f.Datacenters) == 0 && len(f.Targets) == 0
+}
+
+type ServiceResolverFailoverTarget struct {
+	// Service specifies the name of the service to try during failover.
+	Service string `json:",omitempty"`
+
+	// ServiceSubset specifies the service subset to try during failover.
+	ServiceSubset string `json:",omitempty" alias:"service_subset"`
+
+	// Partition specifies the partition to try during failover.
+	Partition string `json:",omitempty"`
+
+	// Namespace specifies the namespace to try during failover.
+	Namespace string `json:",omitempty"`
+
+	// Datacenter specifies the datacenter to try during failover.
+	Datacenter string `json:",omitempty"`
+
+	// Peer specifies the name of the cluster peer to try during failover.
+	Peer string `json:",omitempty"`
 }
 
 // LoadBalancer determines the load balancing policy and configuration for services

agent/structs/config_entry_discoverychain_oss.go

@@ -4,6 +4,8 @@
 package structs
 
 import (
+	"fmt"
+
 	"github.com/hashicorp/consul/acl"
 )
 
@@ -25,12 +27,56 @@ func (redir *ServiceResolverRedirect) GetEnterpriseMeta(_ *acl.EnterpriseMeta) *
 	return DefaultEnterpriseMetaInDefaultPartition()
 }
 
+// ValidateEnterprise validates that enterprise fields are only set
+// with enterprise binaries.
+func (redir *ServiceResolverRedirect) ValidateEnterprise() error {
+	if redir.Partition != "" {
+		return fmt.Errorf("Setting Partition requires Consul Enterprise")
+	}
+
+	if redir.Namespace != "" {
+		return fmt.Errorf("Setting Namespace requires Consul Enterprise")
+	}
+
+	return nil
+}
+
 // GetEnterpriseMeta is used to synthesize the EnterpriseMeta struct from
 // fields in the ServiceResolverFailover
 func (failover *ServiceResolverFailover) GetEnterpriseMeta(_ *acl.EnterpriseMeta) *acl.EnterpriseMeta {
 	return DefaultEnterpriseMetaInDefaultPartition()
 }
 
+// ValidateEnterprise validates that enterprise fields are only set
+// with enterprise binaries.
+func (failover *ServiceResolverFailover) ValidateEnterprise() error {
+	if failover.Namespace != "" {
+		return fmt.Errorf("Setting Namespace requires Consul Enterprise")
+	}
+
+	return nil
+}
+
+// GetEnterpriseMeta is used to synthesize the EnterpriseMeta struct from
+// fields in the ServiceResolverFailoverTarget
+func (target *ServiceResolverFailoverTarget) GetEnterpriseMeta(_ *acl.EnterpriseMeta) *acl.EnterpriseMeta {
+	return DefaultEnterpriseMetaInDefaultPartition()
+}
+
+// ValidateEnterprise validates that enterprise fields are only set
+// with enterprise binaries.
+func (redir *ServiceResolverFailoverTarget) ValidateEnterprise() error {
+	if redir.Partition != "" {
+		return fmt.Errorf("Setting Partition requires Consul Enterprise")
+	}
+
+	if redir.Namespace != "" {
+		return fmt.Errorf("Setting Namespace requires Consul Enterprise")
+	}
+
+	return nil
+}
+
 // GetEnterpriseMeta is used to synthesize the EnterpriseMeta struct from
 // fields in the DiscoveryChainRequest
 func (req *DiscoveryChainRequest) GetEnterpriseMeta() *acl.EnterpriseMeta {

agent/structs/config_entry_discoverychain_oss_test.go

@@ -0,0 +1,131 @@
+//go:build !consulent
+// +build !consulent
+
+package structs
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestServiceResolverConfigEntry_OSS(t *testing.T) {
+	type testcase struct {
+		name         string
+		entry        *ServiceResolverConfigEntry
+		normalizeErr string
+		validateErr  string
+		// check is called between normalize and validate
+		check func(t *testing.T, entry *ServiceResolverConfigEntry)
+	}
+
+	cases := []testcase{
+		{
+			name: "failover with a namespace on OSS",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Service:   "backup",
+						Namespace: "ns1",
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"]: Setting Namespace requires Consul Enterprise`,
+		},
+		{
+			name: "failover Targets cannot set Namespace on OSS",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{{Namespace: "ns1"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"].Targets[0]: Setting Namespace requires Consul Enterprise`,
+		},
+		{
+			name: "failover Targets cannot set Partition on OSS",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{{Partition: "ap1"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"].Targets[0]: Setting Partition requires Consul Enterprise`,
+		},
+		{
+			name: "setting failover Namespace on OSS",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {Namespace: "ns1"},
+				},
+			},
+			validateErr: `Bad Failover["*"]: Setting Namespace requires Consul Enterprise`,
+		},
+	}
+
+	// Bulk add a bunch of similar validation cases.
+	for _, invalidSubset := range invalidSubsetNames {
+		tc := testcase{
+			name: "invalid subset name: " + invalidSubset,
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Subsets: map[string]ServiceResolverSubset{
+					invalidSubset: {OnlyPassing: true},
+				},
+			},
+			validateErr: fmt.Sprintf("Subset %q is invalid", invalidSubset),
+		}
+		cases = append(cases, tc)
+	}
+
+	for _, goodSubset := range validSubsetNames {
+		tc := testcase{
+			name: "valid subset name: " + goodSubset,
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Subsets: map[string]ServiceResolverSubset{
+					goodSubset: {OnlyPassing: true},
+				},
+			},
+		}
+		cases = append(cases, tc)
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			err := tc.entry.Normalize()
+			if tc.normalizeErr != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.normalizeErr)
+				return
+			}
+			require.NoError(t, err)
+
+			if tc.check != nil {
+				tc.check(t, tc.entry)
+			}
+
+			err = tc.entry.Validate()
+			if tc.validateErr != "" {
+				require.Error(t, err)
+				require.Contains(t, err.Error(), tc.validateErr)
+				return
+			}
+			require.NoError(t, err)
+		})
+	}
+}

agent/structs/config_entry_discoverychain_test.go

@@ -165,6 +165,34 @@ func TestConfigEntries_ListRelatedServices_AndACLs(t *testing.T) {
 				},
 			},
 		},
+		{
+			name: "resolver: failover with targets",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{
+							{Service: "other1"},
+							{Datacenter: "dc2"},
+							{Peer: "cluster-01"},
+						},
+					},
+				},
+			},
+			expectServices: []ServiceID{NewServiceID("other1", nil)},
+			expectACLs: []testACL{
+				defaultDenyCase,
+				readTestCase,
+				writeTestCaseDenied,
+				{
+					name:       "can write test (with other1:read)",
+					authorizer: newServiceACL(t, []string{"other1"}, []string{"test"}),
+					canRead:    true,
+					canWrite:   true,
+				},
+			},
+		},
 		{
 			name: "splitter: self",
 			entry: &ServiceSplitterConfigEntry{
@@ -595,6 +623,15 @@ func TestServiceResolverConfigEntry(t *testing.T) {
 			},
 			validateErr: "Redirect is empty",
 		},
+		{
+			name: "empty redirect",
+			entry: &ServiceResolverConfigEntry{
+				Kind:     ServiceResolver,
+				Name:     "test",
+				Redirect: &ServiceResolverRedirect{},
+			},
+			validateErr: "Redirect is empty",
+		},
 		{
 			name: "redirect subset with no service",
 			entry: &ServiceResolverConfigEntry{
@@ -606,17 +643,6 @@ func TestServiceResolverConfigEntry(t *testing.T) {
 			},
 			validateErr: "Redirect.ServiceSubset defined without Redirect.Service",
 		},
-		{
-			name: "redirect namespace with no service",
-			entry: &ServiceResolverConfigEntry{
-				Kind: ServiceResolver,
-				Name: "test",
-				Redirect: &ServiceResolverRedirect{
-					Namespace: "alternate",
-				},
-			},
-			validateErr: "Redirect.Namespace defined without Redirect.Service",
-		},
 		{
 			name: "self redirect with invalid subset",
 			entry: &ServiceResolverConfigEntry{
@@ -695,7 +721,7 @@ func TestServiceResolverConfigEntry(t *testing.T) {
 					"v1": {},
 				},
 			},
-			validateErr: `Bad Failover["v1"] one of Service, ServiceSubset, Namespace, or Datacenters is required`,
+			validateErr: `Bad Failover["v1"]: one of Service, ServiceSubset, Namespace, Targets, or Datacenters is required`,
 		},
 		{
 			name: "failover to self using invalid subset",
@@ -712,7 +738,7 @@ func TestServiceResolverConfigEntry(t *testing.T) {
 					},
 				},
 			},
-			validateErr: `Bad Failover["v1"].ServiceSubset "gone" is not a valid subset of "test"`,
+			validateErr: `Bad Failover["v1"]: ServiceSubset "gone" is not a valid subset of "test"`,
 		},
 		{
 			name: "failover to self using valid subset",
@@ -745,6 +771,109 @@ func TestServiceResolverConfigEntry(t *testing.T) {
 			},
 			validateErr: `Bad Failover["*"].Datacenters: found empty datacenter`,
 		},
+		{
+			name: "failover target with an invalid subset",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{{ServiceSubset: "subset"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"].Targets[0]: ServiceSubset "subset" is not a valid subset of "test"`,
+		},
+		{
+			name: "failover targets can't have Peer and ServiceSubset",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{{Peer: "cluster-01", ServiceSubset: "subset"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"].Targets[0]: Peer cannot be set with ServiceSubset`,
+		},
+		{
+			name: "failover targets can't have Peer and Datacenter",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{{Peer: "cluster-01", Datacenter: "dc1"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"].Targets[0]: Peer cannot be set with Datacenter`,
+		},
+		{
+			name: "failover Targets cannot be set with Datacenters",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Datacenters: []string{"a"},
+						Targets:     []ServiceResolverFailoverTarget{{Peer: "cluster-01"}},
+					},
+				},
+			},
+			validateErr: `Bad Failover["*"]: Targets cannot be set with Datacenters`,
+		},
+		{
+			name: "failover Targets cannot be set with ServiceSubset",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						ServiceSubset: "v2",
+						Targets:       []ServiceResolverFailoverTarget{{Peer: "cluster-01"}},
+					},
+				},
+				Subsets: map[string]ServiceResolverSubset{
+					"v2": {Filter: "Service.Meta.version == v2"},
+				},
+			},
+			validateErr: `Bad Failover["*"]: Targets cannot be set with ServiceSubset`,
+		},
+		{
+			name: "failover Targets cannot be set with Service",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Service: "another-service",
+						Targets: []ServiceResolverFailoverTarget{{Peer: "cluster-01"}},
+					},
+				},
+				Subsets: map[string]ServiceResolverSubset{
+					"v2": {Filter: "Service.Meta.version == v2"},
+				},
+			},
+			validateErr: `Bad Failover["*"]: Targets cannot be set with Service`,
+		},
+		{
+			name: "complicated failover targets",
+			entry: &ServiceResolverConfigEntry{
+				Kind: ServiceResolver,
+				Name: "test",
+				Failover: map[string]ServiceResolverFailover{
+					"*": {
+						Targets: []ServiceResolverFailoverTarget{
+							{Peer: "cluster-01", Service: "test-v2"},
+							{Service: "test-v2", ServiceSubset: "test"},
+							{Datacenter: "dc2"},
+						},
+					},
+				},
+			},
+		},
 		{
 			name: "bad connect timeout",
 			entry: &ServiceResolverConfigEntry{

api/config_entry_discoverychain.go

@@ -225,8 +225,18 @@ type ServiceResolverFailover struct {
 	Service       string `json:",omitempty"`
 	ServiceSubset string `json:",omitempty" alias:"service_subset"`
 	// Referencing other partitions is not supported.
-	Namespace   string   `json:",omitempty"`
-	Datacenters []string `json:",omitempty"`
+	Namespace   string                          `json:",omitempty"`
+	Datacenters []string                        `json:",omitempty"`
+	Targets     []ServiceResolverFailoverTarget `json:",omitempty"`
+}
+
+type ServiceResolverFailoverTarget struct {
+	Service       string `json:",omitempty"`
+	ServiceSubset string `json:",omitempty" alias:"service_subset"`
+	Partition     string `json:",omitempty"`
+	Namespace     string `json:",omitempty"`
+	Datacenter    string `json:",omitempty"`
+	Peer          string `json:",omitempty"`
 }
 
 // LoadBalancer determines the load balancing policy and configuration for services

api/config_entry_discoverychain_test.go

@@ -149,6 +149,9 @@ func TestAPI_ConfigEntry_DiscoveryChain(t *testing.T) {
 					"v2": {
 						Filter: "Service.Meta.version == v2",
 					},
+					"v3": {
+						Filter: "Service.Meta.version == v3",
+					},
 				},
 				Failover: map[string]ServiceResolverFailover{
 					"*": {
@@ -158,6 +161,13 @@ func TestAPI_ConfigEntry_DiscoveryChain(t *testing.T) {
 						Service:   "alternate",
 						Namespace: splitDefaultNamespace,
 					},
+					"v3": {
+						Targets: []ServiceResolverFailoverTarget{
+							{Peer: "cluster-01"},
+							{Datacenter: "dc1"},
+							{Service: "another-service", ServiceSubset: "v1"},
+						},
+					},
 				},
 				ConnectTimeout: 5 * time.Second,
 				Meta: map[string]string{

proto/pbconfigentry/config_entry.gen.go

@@ -630,6 +630,14 @@ func ServiceResolverFailoverToStructs(s *ServiceResolverFailover, t *structs.Ser
 	t.ServiceSubset = s.ServiceSubset
 	t.Namespace = s.Namespace
 	t.Datacenters = s.Datacenters
+	{
+		t.Targets = make([]structs.ServiceResolverFailoverTarget, len(s.Targets))
+		for i := range s.Targets {
+			if s.Targets[i] != nil {
+				ServiceResolverFailoverTargetToStructs(s.Targets[i], &t.Targets[i])
+			}
+		}
+	}
 }
 func ServiceResolverFailoverFromStructs(t *structs.ServiceResolverFailover, s *ServiceResolverFailover) {
 	if s == nil {
@@ -639,6 +647,38 @@ func ServiceResolverFailoverFromStructs(t *structs.ServiceResolverFailover, s *S
 	s.ServiceSubset = t.ServiceSubset
 	s.Namespace = t.Namespace
 	s.Datacenters = t.Datacenters
+	{
+		s.Targets = make([]*ServiceResolverFailoverTarget, len(t.Targets))
+		for i := range t.Targets {
+			{
+				var x ServiceResolverFailoverTarget
+				ServiceResolverFailoverTargetFromStructs(&t.Targets[i], &x)
+				s.Targets[i] = &x
+			}
+		}
+	}
+}
+func ServiceResolverFailoverTargetToStructs(s *ServiceResolverFailoverTarget, t *structs.ServiceResolverFailoverTarget) {
+	if s == nil {
+		return
+	}
+	t.Service = s.Service
+	t.ServiceSubset = s.ServiceSubset
+	t.Partition = s.Partition
+	t.Namespace = s.Namespace
+	t.Datacenter = s.Datacenter
+	t.Peer = s.Peer
+}
+func ServiceResolverFailoverTargetFromStructs(t *structs.ServiceResolverFailoverTarget, s *ServiceResolverFailoverTarget) {
+	if s == nil {
+		return
+	}
+	s.Service = t.Service
+	s.ServiceSubset = t.ServiceSubset
+	s.Partition = t.Partition
+	s.Namespace = t.Namespace
+	s.Datacenter = t.Datacenter
+	s.Peer = t.Peer
 }
 func ServiceResolverRedirectToStructs(s *ServiceResolverRedirect, t *structs.ServiceResolverRedirect) {
 	if s == nil {

proto/pbconfigentry/config_entry.pb.binary.go

@@ -107,6 +107,16 @@ func (msg *ServiceResolverFailover) UnmarshalBinary(b []byte) error {
 	return proto.Unmarshal(b, msg)
 }
 
+// MarshalBinary implements encoding.BinaryMarshaler
+func (msg *ServiceResolverFailoverTarget) MarshalBinary() ([]byte, error) {
+	return proto.Marshal(msg)
+}
+
+// UnmarshalBinary implements encoding.BinaryUnmarshaler
+func (msg *ServiceResolverFailoverTarget) UnmarshalBinary(b []byte) error {
+	return proto.Unmarshal(b, msg)
+}
+
 // MarshalBinary implements encoding.BinaryMarshaler
 func (msg *LoadBalancer) MarshalBinary() ([]byte, error) {
 	return proto.Marshal(msg)

proto/pbconfigentry/config_entry.proto

@@ -134,6 +134,21 @@ message ServiceResolverFailover {
   string ServiceSubset = 2;
   string Namespace = 3;
   repeated string Datacenters = 4;
+  repeated ServiceResolverFailoverTarget Targets = 5;
+}
+
+// mog annotation:
+//
+// target=github.com/hashicorp/consul/agent/structs.ServiceResolverFailoverTarget
+// output=config_entry.gen.go
+// name=Structs
+message ServiceResolverFailoverTarget {
+  string Service = 1;
+  string ServiceSubset = 2;
+  string Partition = 3;
+  string Namespace = 4;
+  string Datacenter = 5;
+  string Peer = 6;
 }
 
 // mog annotation: