vpc network custom mtu support (#4126) (#7567)

Signed-off-by: Modular Magician <[email protected]>

Author: modular-magician

.changelog/4126.txt

@@ -0,0 +1,3 @@
+```release-note:enhancement
+compute: added `mtu` field to `google_compute_network` resource
+```

google/resource_compute_network.go

@@ -18,6 +18,7 @@ import (
 	"fmt"
 	"log"
 	"reflect"
+	"strconv"
 	"time"
 
 	"github.com/hashicorp/terraform-plugin-sdk/v2/helper/schema"
@@ -73,6 +74,14 @@ the user can explicitly connect subnetwork resources.`,
 				ForceNew: true,
 				Description: `An optional description of this resource. The resource must be
 recreated to modify this field.`,
+			},
+			"mtu": {
+				Type:     schema.TypeInt,
+				Computed: true,
+				Optional: true,
+				ForceNew: true,
+				Description: `Maximum Transmission Unit in bytes. The minimum value for this field is 1460
+and the maximum value is 1500 bytes.`,
 			},
 			"routing_mode": {
 				Type:         schema.TypeString,
@@ -143,6 +152,12 @@ func resourceComputeNetworkCreate(d *schema.ResourceData, meta interface{}) erro
 	} else if !isEmptyValue(reflect.ValueOf(routingConfigProp)) {
 		obj["routingConfig"] = routingConfigProp
 	}
+	mtuProp, err := expandComputeNetworkMtu(d.Get("mtu"), d, config)
+	if err != nil {
+		return err
+	} else if v, ok := d.GetOkExists("mtu"); !isEmptyValue(reflect.ValueOf(mtuProp)) && (ok || !reflect.DeepEqual(v, mtuProp)) {
+		obj["mtu"] = mtuProp
+	}
 
 	url, err := replaceVars(d, config, "{{ComputeBasePath}}projects/{{project}}/global/networks")
 	if err != nil {
@@ -289,6 +304,9 @@ func resourceComputeNetworkRead(d *schema.ResourceData, meta interface{}) error
 			}
 		}
 	}
+	if err := d.Set("mtu", flattenComputeNetworkMtu(res["mtu"], d, config)); err != nil {
+		return fmt.Errorf("Error reading Network: %s", err)
+	}
 	if err := d.Set("self_link", ConvertSelfLinkToV1(res["selfLink"].(string))); err != nil {
 		return fmt.Errorf("Error reading Network: %s", err)
 	}
@@ -458,6 +476,23 @@ func flattenComputeNetworkRoutingConfigRoutingMode(v interface{}, d *schema.Reso
 	return v
 }
 
+func flattenComputeNetworkMtu(v interface{}, d *schema.ResourceData, config *Config) interface{} {
+	// Handles the string fixed64 format
+	if strVal, ok := v.(string); ok {
+		if intVal, err := strconv.ParseInt(strVal, 10, 64); err == nil {
+			return intVal
+		}
+	}
+
+	// number values are represented as float64
+	if floatVal, ok := v.(float64); ok {
+		intVal := int(floatVal)
+		return intVal
+	}
+
+	return v // let terraform core handle it otherwise
+}
+
 func expandComputeNetworkDescription(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
 	return v, nil
 }
@@ -485,3 +520,7 @@ func expandComputeNetworkRoutingConfig(v interface{}, d TerraformResourceData, c
 func expandComputeNetworkRoutingConfigRoutingMode(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
 	return v, nil
 }
+
+func expandComputeNetworkMtu(v interface{}, d TerraformResourceData, config *Config) (interface{}, error) {
+	return v, nil
+}

google/resource_compute_network_generated_test.go

@@ -58,6 +58,42 @@ resource "google_compute_network" "vpc_network" {
 `, context)
 }
 
+func TestAccComputeNetwork_networkCustomMtuExample(t *testing.T) {
+	t.Parallel()
+
+	context := map[string]interface{}{
+		"random_suffix": randString(t, 10),
+	}
+
+	vcrTest(t, resource.TestCase{
+		PreCheck:  func() { testAccPreCheck(t) },
+		Providers: testAccProviders,
+		ExternalProviders: map[string]resource.ExternalProvider{
+			"random": {},
+		},
+		CheckDestroy: testAccCheckComputeNetworkDestroyProducer(t),
+		Steps: []resource.TestStep{
+			{
+				Config: testAccComputeNetwork_networkCustomMtuExample(context),
+			},
+			{
+				ResourceName:      "google_compute_network.vpc_network",
+				ImportState:       true,
+				ImportStateVerify: true,
+			},
+		},
+	})
+}
+
+func testAccComputeNetwork_networkCustomMtuExample(context map[string]interface{}) string {
+	return Nprintf(`
+resource "google_compute_network" "vpc_network" {
+  name = "tf-test-vpc-network%{random_suffix}"
+  mtu  = 1500
+}
+`, context)
+}
+
 func testAccCheckComputeNetworkDestroyProducer(t *testing.T) func(s *terraform.State) error {
 	return func(s *terraform.State) error {
 		for name, rs := range s.RootModule().Resources {

website/docs/r/compute_network.html.markdown

@@ -44,6 +44,20 @@ resource "google_compute_network" "vpc_network" {
   name = "vpc-network"
 }
 ```
+<div class = "oics-button" style="float: right; margin: 0 0 -15px">
+  <a href="https://console.cloud.google.com/cloudshell/open?cloudshell_git_repo=https%3A%2F%2Fgithub.jpy.wang%2Fterraform-google-modules%2Fdocs-examples.git&cloudshell_working_dir=network_custom_mtu&cloudshell_image=gcr.io%2Fgraphite-cloud-shell-images%2Fterraform%3Alatest&open_in_editor=main.tf&cloudshell_print=.%2Fmotd&cloudshell_tutorial=.%2Ftutorial.md" target="_blank">
+    <img alt="Open in Cloud Shell" src="//gstatic.com/cloudssh/images/open-btn.svg" style="max-height: 44px; margin: 32px auto; max-width: 100%;">
+  </a>
+</div>
+## Example Usage - Network Custom Mtu
+
+
+```hcl
+resource "google_compute_network" "vpc_network" {
+  name = "vpc-network"
+  mtu  = 1500
+}
+```
 
 ## Argument Reference
 
@@ -86,6 +100,11 @@ The following arguments are supported:
   subnetworks of this network, across regions.
   Possible values are `REGIONAL` and `GLOBAL`.
 
+* `mtu` -
+  (Optional)
+  Maximum Transmission Unit in bytes. The minimum value for this field is 1460
+  and the maximum value is 1500 bytes.
+
 * `project` - (Optional) The ID of the project in which the resource belongs.
     If it is not provided, the provider project is used.