Add /v1/internal/service-virtual-ip for manually setting service VIPs (#17294)

agent/catalog_endpoint.go

@@ -573,3 +573,34 @@ RETRY_ONCE:
 		s.nodeMetricsLabels())
 	return out.Services, nil
 }
+
+func (s *HTTPHandlers) AssignManualServiceVIPs(resp http.ResponseWriter, req *http.Request) (interface{}, error) {
+	metrics.IncrCounterWithLabels([]string{"client", "api", "service_virtual_ips"}, 1,
+		s.nodeMetricsLabels())
+
+	var args structs.AssignServiceManualVIPsRequest
+	if err := s.parseEntMetaNoWildcard(req, &args.EnterpriseMeta); err != nil {
+		return nil, err
+	}
+
+	if err := s.rewordUnknownEnterpriseFieldError(decodeBody(req.Body, &args)); err != nil {
+		return nil, HTTPError{StatusCode: http.StatusBadRequest, Reason: fmt.Sprintf("Request decode failed: %v", err)}
+	}
+
+	// Setup the default DC if not provided
+	if args.Datacenter == "" {
+		args.Datacenter = s.agent.config.Datacenter
+	}
+	s.parseToken(req, &args.Token)
+
+	// Forward to the servers
+	var out structs.AssignServiceManualVIPsResponse
+	if err := s.agent.RPC(req.Context(), "Internal.AssignManualServiceVIPs", &args, &out); err != nil {
+		metrics.IncrCounterWithLabels([]string{"client", "rpc", "error", "service_virtual_ips"}, 1,
+			s.nodeMetricsLabels())
+		return nil, err
+	}
+	metrics.IncrCounterWithLabels([]string{"client", "api", "success", "service_virtual_ips"}, 1,
+		s.nodeMetricsLabels())
+	return out, nil
+}

agent/catalog_endpoint_test.go

@@ -2028,3 +2028,67 @@ func TestCatalog_GatewayServices_Ingress(t *testing.T) {
 		require.Equal(r, expect, gatewayServices)
 	})
 }
+
+func TestCatalogRegister_AssignManualServiceVIPs(t *testing.T) {
+	if testing.Short() {
+		t.Skip("too slow for testing.Short")
+	}
+
+	t.Parallel()
+	a := NewTestAgent(t, "")
+	defer a.Shutdown()
+
+	testrpc.WaitForTestAgent(t, a.RPC, "dc1")
+
+	for _, service := range []string{"api", "web"} {
+		req := structs.ConfigEntryRequest{
+			Datacenter: "dc1",
+			Entry: &structs.ServiceResolverConfigEntry{
+				Kind: structs.ServiceResolver,
+				Name: service,
+			},
+		}
+		var out bool
+		require.NoError(t, a.RPC(context.Background(), "ConfigEntry.Apply", &req, &out))
+	}
+
+	assignVIPs := func(req structs.AssignServiceManualVIPsRequest, expect structs.AssignServiceManualVIPsResponse) {
+		httpReq, _ := http.NewRequest("PUT", "/v1/internal/service-virtual-ip", jsonReader(req))
+		resp := httptest.NewRecorder()
+		obj, err := a.srv.AssignManualServiceVIPs(resp, httpReq)
+		require.NoError(t, err)
+
+		result, ok := obj.(structs.AssignServiceManualVIPsResponse)
+		require.True(t, ok)
+		require.Equal(t, expect, result)
+	}
+
+	// Assign some manual IPs to the service
+	assignVIPs(structs.AssignServiceManualVIPsRequest{
+		Service:    "api",
+		ManualVIPs: []string{"1.1.1.1", "2.2.2.2", "3.3.3.3"},
+	}, structs.AssignServiceManualVIPsResponse{
+		Found: true,
+	})
+
+	// Assign some manual IPs to the new service, reassigning one from the existing service.
+	assignVIPs(structs.AssignServiceManualVIPsRequest{
+		Service:    "web",
+		ManualVIPs: []string{"2.2.2.2", "4.4.4.4"},
+	}, structs.AssignServiceManualVIPsResponse{
+		Found: true,
+		UnassignedFrom: []structs.PeeredServiceName{
+			{
+				ServiceName: structs.ServiceName{Name: "api", EnterpriseMeta: *acl.DefaultEnterpriseMeta()},
+			},
+		},
+	})
+
+	// Assign some manual IPs a non-existent service, should be a no-op.
+	assignVIPs(structs.AssignServiceManualVIPsRequest{
+		Service:    "nope",
+		ManualVIPs: []string{"1.1.1.1", "2.2.2.2", "3.3.3.3", "4.4.4.4"},
+	}, structs.AssignServiceManualVIPsResponse{
+		Found: false,
+	})
+}

agent/consul/fsm/commands_oss.go

@@ -794,9 +794,13 @@ func (c *FSM) applyManualVirtualIPs(buf []byte, index uint64) interface{} {
 		panic(fmt.Errorf("failed to decode request: %v", err))
 	}
 
-	if err := c.state.AssignManualVirtualIPs(index, req.Service, req.ManualIPs); err != nil {
+	found, unassignedFrom, err := c.state.AssignManualServiceVIPs(index, req.Service, req.ManualIPs)
+	if err != nil {
 		c.logger.Warn("AssignManualVirtualIPs failed", "error", err)
 		return err
 	}
-	return nil
+	return structs.AssignServiceManualVIPsResponse{
+		Found:          found,
+		UnassignedFrom: unassignedFrom,
+	}
 }

agent/consul/internal_endpoint.go

@@ -5,6 +5,7 @@ package consul
 
 import (
 	"fmt"
+	"net"
 
 	"github.com/hashicorp/go-bexpr"
 	"github.com/hashicorp/go-hclog"
@@ -17,6 +18,8 @@ import (
 	"github.com/hashicorp/consul/agent/structs"
 )
 
+const MaximumManualVIPsPerService = 8
+
 // Internal endpoint is used to query the miscellaneous info that
 // does not necessarily fit into the other systems. It is also
 // used to hold undocumented APIs that users should not rely on.
@@ -741,6 +744,55 @@ func (m *Internal) PeeredUpstreams(args *structs.PartitionSpecificRequest, reply
 		})
 }
 
+// AssignManualServiceVIPs allows for assigning virtual IPs to a service manually, so that they can
+// be returned along with discovery chain information for use by transparent proxies.
+func (m *Internal) AssignManualServiceVIPs(args *structs.AssignServiceManualVIPsRequest, reply *structs.AssignServiceManualVIPsResponse) error {
+	if done, err := m.srv.ForwardRPC("Internal.AssignManualServiceVIPs", args, reply); done {
+		return err
+	}
+
+	var authzCtx acl.AuthorizerContext
+	authz, err := m.srv.ResolveTokenAndDefaultMeta(args.Token, &args.EnterpriseMeta, &authzCtx)
+	if err != nil {
+		return err
+	}
+	if err := authz.ToAllowAuthorizer().MeshWriteAllowed(&authzCtx); err != nil {
+		return err
+	}
+
+	if err := m.srv.validateEnterpriseRequest(&args.EnterpriseMeta, true); err != nil {
+		return err
+	}
+
+	if len(args.ManualVIPs) > MaximumManualVIPsPerService {
+		return fmt.Errorf("cannot associate more than %d manual virtual IPs with the same service", MaximumManualVIPsPerService)
+	}
+
+	for _, ip := range args.ManualVIPs {
+		parsedIP := net.ParseIP(ip)
+		if parsedIP == nil || parsedIP.To4() == nil {
+			return fmt.Errorf("%q is not a valid IPv4 address", parsedIP.String())
+		}
+	}
+
+	req := state.ServiceVirtualIP{
+		Service: structs.PeeredServiceName{
+			ServiceName: structs.NewServiceName(args.Service, &args.EnterpriseMeta),
+		},
+		ManualIPs: args.ManualVIPs,
+	}
+	resp, err := m.srv.raftApplyMsgpack(structs.UpdateVirtualIPRequestType, req)
+	if err != nil {
+		return err
+	}
+	typedResp, ok := resp.(structs.AssignServiceManualVIPsResponse)
+	if !ok {
+		return fmt.Errorf("unexpected type %T for AssignManualServiceVIPs", resp)
+	}
+	*reply = typedResp
+	return nil
+}
+
 // EventFire is a bit of an odd endpoint, but it allows for a cross-DC RPC
 // call to fire an event. The primary use case is to enable user events being
 // triggered in a remote DC.

agent/consul/internal_endpoint_test.go

@@ -3621,3 +3621,109 @@ func testUUID() string {
 		buf[8:10],
 		buf[10:16])
 }
+
+func TestInternal_AssignManualServiceVIPs(t *testing.T) {
+	if testing.Short() {
+		t.Skip("too slow for testing.Short")
+	}
+	t.Parallel()
+
+	dir1, s1 := testServer(t)
+	defer os.RemoveAll(dir1)
+	defer s1.Shutdown()
+	codec := rpcClient(t, s1)
+	defer codec.Close()
+
+	testrpc.WaitForLeader(t, s1.RPC, "dc1")
+
+	// Set up web service with no manual IPs, and an existing service with manual IPs set.
+	registerReq := structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+		Service: &structs.NodeService{
+			ID:      "web",
+			Service: "web",
+			Port:    8888,
+			Connect: structs.ServiceConnect{Native: true},
+		},
+	}
+	var out struct{}
+	require.NoError(t, msgpackrpc.CallWithCodec(codec, "Catalog.Register", &registerReq, &out))
+
+	registerReq2 := structs.RegisterRequest{
+		Datacenter: "dc1",
+		Node:       "foo",
+		Address:    "127.0.0.1",
+		Service: &structs.NodeService{
+			ID:      "existing",
+			Service: "existing",
+			Port:    9999,
+			Connect: structs.ServiceConnect{Native: true},
+		},
+	}
+	require.NoError(t, msgpackrpc.CallWithCodec(codec, "Catalog.Register", &registerReq2, &out))
+
+	req := structs.AssignServiceManualVIPsRequest{
+		Service:    "existing",
+		ManualVIPs: []string{"8.8.8.8", "9.9.9.9"},
+	}
+	var resp structs.AssignServiceManualVIPsResponse
+	require.NoError(t, msgpackrpc.CallWithCodec(codec, "Internal.AssignManualServiceVIPs", req, &resp))
+
+	type testcase struct {
+		name      string
+		req       structs.AssignServiceManualVIPsRequest
+		expect    structs.AssignServiceManualVIPsResponse
+		expectErr string
+	}
+	run := func(t *testing.T, tc testcase) {
+		var resp structs.AssignServiceManualVIPsResponse
+		err := msgpackrpc.CallWithCodec(codec, "Internal.AssignManualServiceVIPs", tc.req, &resp)
+		if tc.expectErr != "" {
+			require.Error(t, err)
+			require.Contains(t, err.Error(), tc.expectErr)
+			return
+		}
+		require.Equal(t, tc.expect, resp)
+	}
+	tcs := []testcase{
+		{
+			name: "successful manual ip assignment",
+			req: structs.AssignServiceManualVIPsRequest{
+				Service:    "web",
+				ManualVIPs: []string{"1.1.1.1", "2.2.2.2"},
+			},
+			expect: structs.AssignServiceManualVIPsResponse{Found: true},
+		},
+		{
+			name: "reassign existing ip",
+			req: structs.AssignServiceManualVIPsRequest{
+				Service:    "web",
+				ManualVIPs: []string{"8.8.8.8"},
+			},
+			expect: structs.AssignServiceManualVIPsResponse{
+				Found: true,
+				UnassignedFrom: []structs.PeeredServiceName{
+					{
+						ServiceName: structs.ServiceNameFromString("existing"),
+					},
+				},
+			},
+		},
+		{
+			name: "invalid ip",
+			req: structs.AssignServiceManualVIPsRequest{
+				Service:    "web",
+				ManualVIPs: []string{"3.3.3.3", "invalid"},
+			},
+			expect:    structs.AssignServiceManualVIPsResponse{},
+			expectErr: "not a valid",
+		},
+	}
+	for _, tc := range tcs {
+		t.Run(tc.name, func(t *testing.T) {
+			run(t, tc)
+		})
+	}
+}

agent/consul/state/catalog.go

@@ -18,6 +18,7 @@ import (
 	"github.com/hashicorp/consul/agent/structs"
 	"github.com/hashicorp/consul/api"
 	"github.com/hashicorp/consul/lib"
+	"github.com/hashicorp/consul/lib/maps"
 	"github.com/hashicorp/consul/types"
 )
 
@@ -1090,7 +1091,14 @@ func assignServiceVirtualIP(tx WriteTxn, idx uint64, psn structs.PeeredServiceNa
 	return result.String(), nil
 }
 
-func (s *Store) AssignManualVirtualIPs(idx uint64, psn structs.PeeredServiceName, ips []string) error {
+// AssignManualServiceVIPs attempts to associate a list of manual virtual IP addresses with a given service name.
+// Any IP addresses given will be removed from other services in the same partition. This is done to ensure
+// that a manual VIP can only exist once for a given partition.
+// This function returns:
+// - a bool indicating whether the given service exists.
+// - a list of service names that had ip addresses removed from them.
+// - an error indicating success or failure of the call.
+func (s *Store) AssignManualServiceVIPs(idx uint64, psn structs.PeeredServiceName, ips []string) (bool, []structs.PeeredServiceName, error) {
 	tx := s.db.WriteTxn(idx)
 	defer tx.Abort()
 
@@ -1099,10 +1107,11 @@ func (s *Store) AssignManualVirtualIPs(idx uint64, psn structs.PeeredServiceName
 	for _, ip := range ips {
 		assignedIPs[ip] = struct{}{}
 	}
+	modifiedEntries := make(map[structs.PeeredServiceName]struct{})
 	for ip := range assignedIPs {
 		entry, err := tx.First(tableServiceVirtualIPs, indexManualVIPs, psn.ServiceName.PartitionOrDefault(), ip)
 		if err != nil {
-			return fmt.Errorf("failed service virtual IP lookup: %s", err)
+			return false, nil, fmt.Errorf("failed service virtual IP lookup: %s", err)
 		}
 
 		if entry == nil {
@@ -1126,17 +1135,18 @@ func (s *Store) AssignManualVirtualIPs(idx uint64, psn structs.PeeredServiceName
 		newEntry.ManualIPs = filteredIPs
 		newEntry.ModifyIndex = idx
 		if err := tx.Insert(tableServiceVirtualIPs, newEntry); err != nil {
-			return fmt.Errorf("failed inserting service virtual IP entry: %s", err)
+			return false, nil, fmt.Errorf("failed inserting service virtual IP entry: %s", err)
 		}
+		modifiedEntries[newEntry.Service] = struct{}{}
 	}
 
 	entry, err := tx.First(tableServiceVirtualIPs, indexID, psn)
 	if err != nil {
-		return fmt.Errorf("failed service virtual IP lookup: %s", err)
+		return false, nil, fmt.Errorf("failed service virtual IP lookup: %s", err)
 	}
 
 	if entry == nil {
-		return nil
+		return false, nil, nil
 	}
 
 	newEntry := entry.(ServiceVirtualIP)
@@ -1144,13 +1154,16 @@ func (s *Store) AssignManualVirtualIPs(idx uint64, psn structs.PeeredServiceName
 	newEntry.ModifyIndex = idx
 
 	if err := tx.Insert(tableServiceVirtualIPs, newEntry); err != nil {
-		return fmt.Errorf("failed inserting service virtual IP entry: %s", err)
+		return false, nil, fmt.Errorf("failed inserting service virtual IP entry: %s", err)
 	}
 	if err := updateVirtualIPMaxIndexes(tx, idx, psn.ServiceName.PartitionOrDefault(), psn.Peer); err != nil {
-		return err
+		return false, nil, err
+	}
+	if err = tx.Commit(); err != nil {
+		return false, nil, err
 	}
 
-	return tx.Commit()
+	return true, maps.SliceOfKeys(modifiedEntries), nil
 }
 
 func updateVirtualIPMaxIndexes(txn WriteTxn, idx uint64, partition, peerName string) error {

agent/consul/state/catalog_test.go

@@ -1964,8 +1964,11 @@ func TestStateStore_AssignManualVirtualIPs(t *testing.T) {
 	setVirtualIPFlags(t, s)
 
 	// Attempt to assign manual virtual IPs to a service that doesn't exist - should be a no-op.
-	psn := structs.PeeredServiceName{ServiceName: structs.ServiceName{Name: "foo"}}
+	psn := structs.PeeredServiceName{ServiceName: structs.ServiceName{Name: "foo", EnterpriseMeta: *acl.DefaultEnterpriseMeta()}}
-	require.NoError(t, s.AssignManualVirtualIPs(0, psn, []string{"7.7.7.7", "8.8.8.8"}))
+	found, svcs, err := s.AssignManualServiceVIPs(0, psn, []string{"7.7.7.7", "8.8.8.8"})
+	require.NoError(t, err)
+	require.False(t, found)
+	require.Empty(t, svcs)
 	serviceVIP, err := s.ServiceManualVIPs(psn)
 	require.NoError(t, err)
 	require.Nil(t, serviceVIP)
@@ -1997,24 +2000,20 @@ func TestStateStore_AssignManualVirtualIPs(t *testing.T) {
 	require.Empty(t, serviceVIP.ManualIPs)
 
 	// Attempt to assign manual virtual IPs again.
-	require.NoError(t, s.AssignManualVirtualIPs(2, psn, []string{"7.7.7.7", "8.8.8.8"}))
+	found, svcs, err = s.AssignManualServiceVIPs(2, psn, []string{"7.7.7.7", "8.8.8.8"})
+	require.NoError(t, err)
+	require.True(t, found)
+	require.Empty(t, svcs)
 	serviceVIP, err = s.ServiceManualVIPs(psn)
 	require.NoError(t, err)
 	require.Equal(t, "0.0.0.1", serviceVIP.IP.String())
 	require.Equal(t, serviceVIP.ManualIPs, []string{"7.7.7.7", "8.8.8.8"})
 
-	// Register another service
+	// Register another service via config entry.
-	ns2 := &structs.NodeService{
+	s.EnsureConfigEntry(3, &structs.ServiceResolverConfigEntry{
-		ID:             "bar",
+		Kind: structs.ServiceResolver,
-		Service:        "bar",
+		Name: "bar",
-		Address:        "2.2.2.2",
+	})
-		Port:           2222,
-		Connect:        structs.ServiceConnect{Native: true},
-		EnterpriseMeta: *entMeta,
-	}
-
-	// Service successfully registers into the state store.
-	require.NoError(t, s.EnsureService(3, "node1", ns2))
 
 	psn2 := structs.PeeredServiceName{ServiceName: structs.ServiceName{Name: "bar"}}
 	vip, err = s.VirtualIPForService(psn2)
@@ -2023,7 +2022,10 @@ func TestStateStore_AssignManualVirtualIPs(t *testing.T) {
 
 	// Attempt to assign manual virtual IPs for bar, with one IP overlapping with foo.
 	// This should cause the ip to be removed from foo's list of manual IPs.
-	require.NoError(t, s.AssignManualVirtualIPs(4, psn2, []string{"7.7.7.7", "9.9.9.9"}))
+	found, svcs, err = s.AssignManualServiceVIPs(4, psn2, []string{"7.7.7.7", "9.9.9.9"})
+	require.NoError(t, err)
+	require.True(t, found)
+	require.ElementsMatch(t, svcs, []structs.PeeredServiceName{psn})
 
 	serviceVIP, err = s.ServiceManualVIPs(psn)
 	require.NoError(t, err)

agent/http_register.go

@@ -100,6 +100,7 @@ func init() {
 	registerEndpoint("/v1/internal/ui/gateway-intentions/", []string{"GET"}, (*HTTPHandlers).UIGatewayIntentions)
 	registerEndpoint("/v1/internal/ui/service-topology/", []string{"GET"}, (*HTTPHandlers).UIServiceTopology)
 	registerEndpoint("/v1/internal/acl/authorize", []string{"POST"}, (*HTTPHandlers).ACLAuthorize)
+	registerEndpoint("/v1/internal/service-virtual-ip", []string{"PUT"}, (*HTTPHandlers).AssignManualServiceVIPs)
 	registerEndpoint("/v1/kv/", []string{"GET", "PUT", "DELETE"}, (*HTTPHandlers).KVSEndpoint)
 	registerEndpoint("/v1/operator/raft/configuration", []string{"GET"}, (*HTTPHandlers).OperatorRaftConfiguration)
 	registerEndpoint("/v1/operator/raft/transfer-leader", []string{"POST"}, (*HTTPHandlers).OperatorRaftTransferLeader)

agent/structs/catalog.go

@@ -59,3 +59,15 @@ func (h *HealthSummary) Add(status string) {
 		h.Critical++
 	}
 }
+
+type AssignServiceManualVIPsRequest struct {
+	Service    string
+	ManualVIPs []string
+
+	DCSpecificRequest
+}
+
+type AssignServiceManualVIPsResponse struct {
+	Found          bool
+	UnassignedFrom []PeeredServiceName
+}

api/internal.go

@@ -0,0 +1,64 @@
+package api
+
+import "context"
+
+// Internal can be used to query endpoints that are intended for
+// Hashicorp internal-use only.
+type Internal struct {
+	c *Client
+}
+
+// Internal returns a handle to endpoints that are for internal
+// Hashicorp usage only. There is not guarantee that these will
+// be backwards-compatible or supported, so usage of these is
+// not encouraged.
+func (c *Client) Internal() *Internal {
+	return &Internal{c}
+}
+
+type AssignServiceManualVIPsRequest struct {
+	Service    string
+	ManualVIPs []string
+}
+
+type AssignServiceManualVIPsResponse struct {
+	ServiceFound   bool `json:"Found"`
+	UnassignedFrom []PeeredServiceName
+}
+
+type PeeredServiceName struct {
+	ServiceName CompoundServiceName
+	Peer        string
+}
+
+func (i *Internal) AssignServiceVirtualIP(
+	ctx context.Context,
+	service string,
+	manualVIPs []string,
+	wo *WriteOptions,
+) (*AssignServiceManualVIPsResponse, *QueryMeta, error) {
+	req := i.c.newRequest("PUT", "/v1/internal/service-virtual-ip")
+	req.setWriteOptions(wo)
+	req.ctx = ctx
+	req.obj = AssignServiceManualVIPsRequest{
+		Service:    service,
+		ManualVIPs: manualVIPs,
+	}
+	rtt, resp, err := i.c.doRequest(req)
+	if err != nil {
+		return nil, nil, err
+	}
+	defer closeResponseBody(resp)
+	if err := requireOK(resp); err != nil {
+		return nil, nil, err
+	}
+
+	qm := &QueryMeta{RequestTime: rtt}
+	parseQueryMeta(resp, qm)
+
+	var out AssignServiceManualVIPsResponse
+	if err := decodeBody(resp, &out); err != nil {
+		return nil, nil, err
+	}
+	return &out, qm, nil
+}

api/internal_test.go

@@ -0,0 +1,114 @@
+package api
+
+import (
+	"context"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestAPI_Internal_AssignServiceVirtualIP(t *testing.T) {
+	t.Parallel()
+	doTest_Internal_AssignServiceVirtualIP(t, &WriteOptions{
+		Namespace: defaultNamespace,
+		Partition: defaultPartition,
+	})
+}
+
+func doTest_Internal_AssignServiceVirtualIP(t *testing.T, writeOpts *WriteOptions) {
+	c, s := makeClient(t)
+	defer s.Stop()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 20*time.Second)
+	defer cancel()
+
+	if writeOpts.Partition != "" {
+		_, _, err := c.Partitions().Create(ctx, &Partition{Name: writeOpts.Partition}, nil)
+		require.NoError(t, err)
+	}
+	if writeOpts.Namespace != "" {
+		_, _, err := c.Namespaces().Create(&Namespace{Name: writeOpts.Namespace, Partition: writeOpts.Partition}, nil)
+		require.NoError(t, err)
+	}
+
+	// Create resolvers that we can attach VIPs to.
+	for _, name := range []string{"one", "two", "three"} {
+		ok, _, err := c.ConfigEntries().Set(&ServiceResolverConfigEntry{
+			Kind:      ServiceResolver,
+			Name:      name,
+			Namespace: writeOpts.Namespace,
+			Partition: writeOpts.Partition,
+		}, writeOpts)
+		require.NoError(t, err)
+		require.True(t, ok)
+	}
+
+	tests := []struct {
+		tName                string
+		svcName              string
+		vips                 []string
+		expectFound          bool
+		expectUnassignedFrom []PeeredServiceName
+	}{
+		{
+			tName:                "missing service is no-op",
+			svcName:              "missing",
+			vips:                 []string{"1.1.1.1", "2.2.2.2"},
+			expectFound:          false,
+			expectUnassignedFrom: nil,
+		},
+		{
+			tName:                "set vips for one",
+			svcName:              "one",
+			vips:                 []string{"1.1.1.1", "2.2.2.2", "3.3.3.3"},
+			expectFound:          true,
+			expectUnassignedFrom: nil,
+		},
+		{
+			tName:       "move vip to two",
+			svcName:     "two",
+			vips:        []string{"2.2.2.2"},
+			expectFound: true,
+			expectUnassignedFrom: []PeeredServiceName{
+				{ServiceName: CompoundServiceName{Name: "one", Namespace: writeOpts.Namespace, Partition: writeOpts.Partition}},
+			},
+		},
+		{
+			tName:       "move vip to three",
+			svcName:     "three",
+			vips:        []string{"3.3.3.3"},
+			expectFound: true,
+			expectUnassignedFrom: []PeeredServiceName{
+				{ServiceName: CompoundServiceName{Name: "one", Namespace: writeOpts.Namespace, Partition: writeOpts.Partition}},
+			},
+		},
+		{
+			tName:                "no-op try move vips to missing",
+			svcName:              "missing",
+			vips:                 []string{"1.1.1.1", "2.2.2.2", "3.3.3.3"},
+			expectFound:          false,
+			expectUnassignedFrom: nil,
+		},
+		{
+			tName:       "move all vips back to one",
+			svcName:     "one",
+			vips:        []string{"1.1.1.1", "2.2.2.2", "3.3.3.3", "4.4.4.4"},
+			expectFound: true,
+			expectUnassignedFrom: []PeeredServiceName{
+				{ServiceName: CompoundServiceName{Name: "two", Namespace: writeOpts.Namespace, Partition: writeOpts.Partition}},
+				{ServiceName: CompoundServiceName{Name: "three", Namespace: writeOpts.Namespace, Partition: writeOpts.Partition}},
+			},
+		},
+	}
+
+	internal := c.Internal()
+	for _, tc := range tests {
+		t.Run(tc.tName, func(t *testing.T) {
+			resp, _, err := internal.AssignServiceVirtualIP(ctx, tc.svcName, tc.vips, writeOpts)
+			require.NoError(t, err)
+			require.Equal(t, tc.expectFound, resp.ServiceFound)
+			require.ElementsMatch(t, tc.expectUnassignedFrom, resp.UnassignedFrom)
+		})
+	}
+}