From 0e2c4da3e27d5f3a54bf1cc93b416da4e05b681b Mon Sep 17 00:00:00 2001
From: Paddy <paddy@hashicorp.com>
Date: Mon, 7 Nov 2016 16:00:42 -0800
Subject: [PATCH] provider/google: throw an error for invalid disks

When configuring an instance's attached disk, if the attached disk has
both the disk and type attributes set, it would previously cause
terraform to crash with a nil pointer exception. The root cause was that
we only instantiate the InitializeParams property of the disk if its
disk attribute isn't set, and we try to write to the InitializeParams
property when the type attribute is set. So setting both caused the
InitializeParams property to not be initialized, then written to.

Now we throw an error explaining that the configuration can't have both
the disk and the type set.

Fixes #6495.
---
 resource_compute_instance.go      |  7 +++++
 resource_compute_instance_test.go | 49 +++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/resource_compute_instance.go b/resource_compute_instance.go
index dd413440..3b54708f 100644
--- a/resource_compute_instance.go
+++ b/resource_compute_instance.go
@@ -361,6 +361,13 @@ func resourceComputeInstanceCreate(d *schema.ResourceData, meta interface{}) err
 		disk.Boot = i == 0
 		disk.AutoDelete = d.Get(prefix + ".auto_delete").(bool)
 
+		if _, ok := d.GetOk(prefix + ".disk"); ok {
+			if _, ok := d.GetOk(prefix + ".type"); ok {
+				return fmt.Errorf(
+					"Error: cannot define both disk and type.")
+			}
+		}
+
 		// Load up the disk for this disk if specified
 		if v, ok := d.GetOk(prefix + ".disk"); ok {
 			diskName := v.(string)
diff --git a/resource_compute_instance_test.go b/resource_compute_instance_test.go
index 7ea120e2..33b82aa7 100644
--- a/resource_compute_instance_test.go
+++ b/resource_compute_instance_test.go
@@ -2,6 +2,7 @@ package google
 
 import (
 	"fmt"
+	"regexp"
 	"strings"
 	"testing"
 
@@ -482,6 +483,23 @@ func TestAccComputeInstance_private_image_family(t *testing.T) {
 	})
 }
 
+func TestAccComputeInstance_invalid_disk(t *testing.T) {
+	var instanceName = fmt.Sprintf("instance-test-%s", acctest.RandString(10))
+	var diskName = fmt.Sprintf("instance-testd-%s", acctest.RandString(10))
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckComputeInstanceDestroy,
+		Steps: []resource.TestStep{
+			resource.TestStep{
+				Config:      testAccComputeInstance_invalid_disk(diskName, instanceName),
+				ExpectError: regexp.MustCompile("Error: cannot define both disk and type."),
+			},
+		},
+	})
+}
+
 func testAccCheckComputeInstanceDestroy(s *terraform.State) error {
 	config := testAccProvider.Meta().(*Config)
 
@@ -1152,3 +1170,34 @@ func testAccComputeInstance_private_image_family(disk, image, family, instance s
 			}
 		}`, disk, image, family, instance)
 }
+
+func testAccComputeInstance_invalid_disk(disk, instance string) string {
+	return fmt.Sprintf(`
+		resource "google_compute_instance" "foobar" {
+		  name         = "%s"
+		  machine_type = "f1-micro"
+		  zone         = "us-central1-a"
+
+		  disk {
+		    image = "ubuntu-os-cloud/ubuntu-1604-lts"
+		    type  = "pd-standard"
+		  }
+
+		  disk {
+		    disk        = "${google_compute_disk.foobar.name}"
+		    type        = "pd-standard"
+		    device_name = "xvdb"
+		  }
+
+		  network_interface {
+		    network = "default"
+		  }
+		}
+
+		resource "google_compute_disk" "foobar" {
+		  name = "%s"
+		  zone = "us-central1-a"
+		  type = "pd-standard"
+		  size = "1"
+		}`, instance, disk)
+}