google_compute_instance can specified the subnetwork using a self_link (#290)

google/provider.go

@@ -13,6 +13,7 @@ import (
 	computeBeta "google.golang.org/api/compute/v0.beta"
 	"google.golang.org/api/compute/v1"
 	"google.golang.org/api/googleapi"
+	"regexp"
 )
 
 // Global MutexKV
@@ -273,6 +274,46 @@ func getNetworkLink(d *schema.ResourceData, config *Config, field string) (strin
 	}
 }
 
+// Reads the "subnetwork" fields from the given resource data and if the value is:
+// - a resource URL, returns the string unchanged
+// - a subnetwork name, looks up the resource URL using the google client.
+//
+// If `subnetworkField` is a resource url, `subnetworkProjectField` cannot be set.
+// If `subnetworkField` is a subnetwork name, `subnetworkProjectField` will be used
+// 	as the project if set. If not, we fallback on the default project.
+func getSubnetworkLink(d *schema.ResourceData, config *Config, subnetworkField, subnetworkProjectField, zoneField string) (string, error) {
+	if v, ok := d.GetOk(subnetworkField); ok {
+		subnetwork := v.(string)
+		r := regexp.MustCompile(SubnetworkLinkRegex)
+		if r.MatchString(subnetwork) {
+			return subnetwork, nil
+		}
+
+		var project string
+		if subnetworkProject, ok := d.GetOk(subnetworkProjectField); ok {
+			project = subnetworkProject.(string)
+		} else {
+			var err error
+			project, err = getProject(d, config)
+			if err != nil {
+				return "", err
+			}
+		}
+
+		region := getRegionFromZone(d.Get(zoneField).(string))
+
+		subnet, err := config.clientCompute.Subnetworks.Get(project, region, subnetwork).Do()
+		if err != nil {
+			return "", fmt.Errorf(
+				"Error referencing subnetwork '%s' in region '%s': %s",
+				subnetwork, region, err)
+		}
+
+		return subnet.SelfLink, nil
+	}
+	return "", nil
+}
+
 // getNetworkName reads the "network" field from the given resource data and if the value:
 // - is a resource URL, extracts the network name from the URL and returns it
 // - is the network name only (i.e not prefixed with http://www.googleapis.com/compute/...), is returned unchanged

google/resource_compute_instance.go

@@ -9,6 +9,7 @@ import (
 	"github.com/hashicorp/terraform/helper/validation"
 	"google.golang.org/api/compute/v1"
 	"google.golang.org/api/googleapi"
+	"regexp"
 )
 
 func stringScopeHashcode(v interface{}) int {
@@ -278,20 +279,26 @@ func resourceComputeInstance() *schema.Resource {
 				Elem: &schema.Resource{
 					Schema: map[string]*schema.Schema{
 						"network": &schema.Schema{
-							Type:     schema.TypeString,
+							Type:             schema.TypeString,
-							Optional: true,
+							Optional:         true,
-							ForceNew: true,
+							Computed:         true,
+							ForceNew:         true,
+							DiffSuppressFunc: linkDiffSuppress,
+							ConflictsWith:    []string{"network_interface.0.subnetwork", "network_interface.0.subnetwork_project"},
 						},
 
 						"subnetwork": &schema.Schema{
-							Type:     schema.TypeString,
+							Type:             schema.TypeString,
-							Optional: true,
+							Optional:         true,
-							ForceNew: true,
+							Computed:         true,
+							ForceNew:         true,
+							DiffSuppressFunc: linkDiffSuppress,
 						},
 
 						"subnetwork_project": &schema.Schema{
 							Type:     schema.TypeString,
 							Optional: true,
+							Computed: true,
 							ForceNew: true,
 						},
 
@@ -704,34 +711,21 @@ func resourceComputeInstanceCreate(d *schema.ResourceData, meta interface{}) err
 			prefix := fmt.Sprintf("network_interface.%d", i)
 			// Load up the name of this network_interface
 			networkName := d.Get(prefix + ".network").(string)
-			subnetworkName := d.Get(prefix + ".subnetwork").(string)
-			subnetworkProject := d.Get(prefix + ".subnetwork_project").(string)
 			address := d.Get(prefix + ".address").(string)
 			var networkLink, subnetworkLink string
 
-			if networkName != "" && subnetworkName != "" {
+			if networkName != "" {
-				return fmt.Errorf("Cannot specify both network and subnetwork values.")
-			} else if networkName != "" {
 				networkLink, err = getNetworkLink(d, config, prefix+".network")
 				if err != nil {
 					return fmt.Errorf(
 						"Error referencing network '%s': %s",
 						networkName, err)
 				}
-
 			} else {
-				region := getRegionFromZone(d.Get("zone").(string))
+				subnetworkLink, err = getSubnetworkLink(d, config, prefix+".subnetwork", prefix+".subnetwork_project", "zone")
-				if subnetworkProject == "" {
-					subnetworkProject = project
-				}
-				subnetwork, err := config.clientCompute.Subnetworks.Get(
-					subnetworkProject, region, subnetworkName).Do()
 				if err != nil {
-					return fmt.Errorf(
+					return err
-						"Error referencing subnetwork '%s' in region '%s': %s",
-						subnetworkName, region, err)
 				}
-				subnetworkLink = subnetwork.SelfLink
 			}
 
 			// Build the networkInterface
@@ -961,9 +955,9 @@ func resourceComputeInstanceRead(d *schema.ResourceData, meta interface{}) error
 			networkInterfaces = append(networkInterfaces, map[string]interface{}{
 				"name":               iface.Name,
 				"address":            iface.NetworkIP,
-				"network":            d.Get(fmt.Sprintf("network_interface.%d.network", i)),
+				"network":            iface.Network,
-				"subnetwork":         d.Get(fmt.Sprintf("network_interface.%d.subnetwork", i)),
+				"subnetwork":         iface.Subnetwork,
-				"subnetwork_project": d.Get(fmt.Sprintf("network_interface.%d.subnetwork_project", i)),
+				"subnetwork_project": getProjectFromSubnetworkLink(iface.Subnetwork),
 				"access_config":      accessConfigs,
 			})
 		}
@@ -1452,3 +1446,12 @@ func flattenScratchDisk(disk *compute.AttachedDisk) map[string]interface{} {
 	}
 	return result
 }
+
+func getProjectFromSubnetworkLink(subnetwork string) string {
+	r := regexp.MustCompile(SubnetworkLinkRegex)
+	if !r.MatchString(subnetwork) {
+		return ""
+	}
+
+	return r.FindStringSubmatch(subnetwork)[1]
+}

google/resource_compute_instance_test.go

@@ -1609,7 +1609,7 @@ resource "google_compute_instance" "foobar" {
 	}
 
 	network_interface {
-		subnetwork = "${google_compute_subnetwork.inst-test-subnetwork.name}"
+		subnetwork = "${google_compute_subnetwork.inst-test-subnetwork.self_link}"
 		access_config {	}
 	}
 

google/validation.go

@@ -6,8 +6,14 @@ import (
 	"regexp"
 )
 
-// Copied from the official Google Cloud auto-generated client.
+const (
-const ProjectRegex = "(?:(?:[-a-z0-9]{1,63}\\.)*(?:[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?):)?(?:[0-9]{1,19}|(?:[a-z0-9](?:[-a-z0-9]{0,61}[a-z0-9])?))"
+	// Copied from the official Google Cloud auto-generated client.
+	ProjectRegex    = "(?:(?:[-a-z0-9]{1,63}\\.)*(?:[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?):)?(?:[0-9]{1,19}|(?:[a-z0-9](?:[-a-z0-9]{0,61}[a-z0-9])?))"
+	RegionRegex     = "[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?"
+	SubnetworkRegex = "[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?"
+
+	SubnetworkLinkRegex = "projects/(" + ProjectRegex + ")/regions/(" + RegionRegex + ")/subnetworks/(" + SubnetworkRegex + ")$"
+)
 
 func validateGCPName(v interface{}, k string) (ws []string, errors []error) {
 	re := `^(?:[a-z](?:[-a-z0-9]{0,61}[a-z0-9])?)$`

website/docs/r/compute_instance.html.markdown

@@ -210,12 +210,14 @@ The `network_interface` block supports:
 * `network` - (Optional) The name or self_link of the network to attach this interface to.
     Either `network` or `subnetwork` must be provided.
 
-*  `subnetwork` - (Optional) The name of the subnetwork to attach this interface
+*  `subnetwork` - (Optional) The name or self_link of the subnetwork to attach this
-    to. The subnetwork must exist in the same region this instance will be
+    interface to. The subnetwork must exist in the same region this instance will be
     created in. Either `network` or `subnetwork` must be provided.
 
 *  `subnetwork_project` - (Optional) The project in which the subnetwork belongs.
-   If it is not provided, the provider project is used.
+   If the `subnetwork` is a self_link, this field is ignored in favor of the project
+   defined in the subnetwork self_link. If the `subnetwork` is a name and this
+   field is not provided, the provider project is used.
 
 * `address` - (Optional) The private IP address to assign to the instance. If
     empty, the address will be automatically assigned.