Use port's to value when building service address under 'alloc' addr_mode

CHANGELOG.md

@@ -6,6 +6,7 @@ IMPROVEMENTS:
 
 BUG FIXES:
  * consul: Fixed a bug where updating a task to include services would not work [[GH-9707](https://github.com/hashicorp/nomad/issues/9707)]
+ * consul: Fixed alloc address mode port advertisement to use the mapped `to` port value [[GH-9730](https://github.com/hashicorp/nomad/issues/9730)]
  * consul/connect: Fixed a bug where absent ingress envoy proxy configuration could panic client [[GH-9669](https://github.com/hashicorp/nomad/issues/9669)]
  * template: Fixed multiple issues in template src/dest and artifact dest interpolation [[GH-9671](https://github.com/hashicorp/nomad/issues/9671)]
  * template: Fixed a bug where dynamic secrets did not trigger the template `change_mode` after a client restart. [[GH-9636](https://github.com/hashicorp/nomad/issues/9636)]

command/agent/consul/service_client.go

@@ -1560,7 +1560,7 @@ func getAddress(addrMode, portLabel string, networks structs.Networks, driverNet
 
 		return driverNet.IP, port, nil
 
-	case "alloc":
+	case structs.AddressModeAlloc:
 		if netStatus == nil {
 			return "", 0, fmt.Errorf(`cannot use address_mode="alloc": no allocation network status reported`)
 		}
@@ -1572,6 +1572,10 @@ func getAddress(addrMode, portLabel string, networks structs.Networks, driverNet
 
 		// If port is a label and is found then return it
 		if port, ok := ports.Get(portLabel); ok {
+			// Use port.To value unless not set
+			if port.To > 0 {
+				return netStatus.Address, port.To, nil
+			}
 			return netStatus.Address, port.Value, nil
 		}
 

command/agent/consul/unit_test.go

@@ -1632,6 +1632,24 @@ func TestGetAddress(t *testing.T) {
 				Address:       "172.26.0.1",
 			},
 			ExpectedIP:   "172.26.0.1",
+			ExpectedPort: 6379,
+		},
+		{
+			Name:      "Alloc no to value",
+			Mode:      structs.AddressModeAlloc,
+			PortLabel: "db",
+			Ports: []structs.AllocatedPortMapping{
+				{
+					Label:  "db",
+					Value:  12345,
+					HostIP: HostIP,
+				},
+			},
+			Status: &structs.AllocNetworkStatus{
+				InterfaceName: "eth0",
+				Address:       "172.26.0.1",
+			},
+			ExpectedIP:   "172.26.0.1",
 			ExpectedPort: 12345,
 		},
 		{

website/content/docs/job-specification/service.mdx

@@ -106,9 +106,13 @@ Connect][connect] integration.
   service. The value of `port` depends on which [`address_mode`](#address_mode)
   is being used:
 
+  - `alloc` - Advertise the mapped `to` value of the labeled port and the allocation address.
+    If a `to` value is not set, the port falls back to using the allocated host port. The `port`
+    field may be a numeric port or a port label specified in the same group's network stanza.
+
   - `driver` - Advertise the port determined by the driver (e.g. Docker or rkt).
     The `port` may be a numeric port or a port label specified in the driver's
-    `port_map`.
+    `ports` field.
 
   - `host` - Advertise the host port for this service. `port` must match a port
     _label_ specified in the [`network`][network] stanza.