instance_interruption_behaviour -> instance_interruption_behavior

US Spelling to match the AWS API and the docs.
While this is technically a breaking change this didn't work anyway.
See discussion at hashicorp#1986 (comment)

aws/resource_aws_spot_instance_request.go

@@ -78,11 +78,12 @@ func resourceAwsSpotInstanceRequest() *schema.Resource {
 				Optional: true,
 				ForceNew: true,
 			}
-			s["instance_interruption_behaviour"] = &schema.Schema{
+			s["instance_interruption_behavior"] = &schema.Schema{
 				Type:     schema.TypeString,
 				Optional: true,
 				Default:  "terminate",
 				ForceNew: true,
+				ValidateFunc: validateInstanceInterruptionBehavior,
 			}
 			return s
 		}(),
@@ -100,7 +101,7 @@ func resourceAwsSpotInstanceRequestCreate(d *schema.ResourceData, meta interface
 	spotOpts := &ec2.RequestSpotInstancesInput{
 		SpotPrice: aws.String(d.Get("spot_price").(string)),
 		Type:      aws.String(d.Get("spot_type").(string)),
-		InstanceInterruptionBehavior: aws.String(d.Get("instance_interruption_behaviour").(string)),
+		InstanceInterruptionBehavior: aws.String(d.Get("instance_interruption_behavior").(string)),
 
 		// Though the AWS API supports creating spot instance requests for multiple
 		// instances, for TF purposes we fix this to one instance per request.
@@ -132,7 +133,7 @@ func resourceAwsSpotInstanceRequestCreate(d *schema.ResourceData, meta interface
 	}
 
 	// Placement GroupName can only be specified when instanceInterruptionBehavior is not set to 'stop'
-	if v, exists := d.GetOkExists("instance_interruption_behaviour"); v == "terminate" || !exists {
+	if v, exists := d.GetOkExists("instance_interruption_behavior"); v == "terminate" || !exists {
 		spotOpts.LaunchSpecification.Placement = instanceOpts.SpotPlacement
 	}
 
@@ -239,7 +240,7 @@ func resourceAwsSpotInstanceRequestRead(d *schema.ResourceData, meta interface{}
 	d.Set("launch_group", request.LaunchGroup)
 	d.Set("block_duration_minutes", request.BlockDurationMinutes)
 	d.Set("tags", tagsToMap(request.Tags))
-	d.Set("instance_interruption_behaviour", request.InstanceInterruptionBehavior)
+	d.Set("instance_interruption_behavior", request.InstanceInterruptionBehavior)
 
 	return nil
 }

aws/resource_aws_spot_instance_request_test.go

@@ -33,7 +33,7 @@ func TestAccAWSSpotInstanceRequest_basic(t *testing.T) {
 					resource.TestCheckResourceAttr(
 						"aws_spot_instance_request.foo", "spot_request_state", "active"),
 					resource.TestCheckResourceAttr(
-						"aws_spot_instance_request.foo", "instance_interruption_behaviour", "terminate"),
+						"aws_spot_instance_request.foo", "instance_interruption_behavior", "terminate"),
 				),
 			},
 		},
@@ -379,7 +379,7 @@ func TestAccAWSSpotInstanceRequestStopInterrupt(t *testing.T) {
 					resource.TestCheckResourceAttr(
 						"aws_spot_instance_request.foo", "spot_request_state", "active"),
 					resource.TestCheckResourceAttr(
-						"aws_spot_instance_request.foo", "instance_interruption_behaviour", "stop"),
+						"aws_spot_instance_request.foo", "instance_interruption_behavior", "stop"),
 				),
 			},
 		},
@@ -562,6 +562,6 @@ func testAccAWSSpotInstanceRequestStopInterruptConfig() string {
 		// and verify termination behavior
 		wait_for_fulfillment = true
 
-		instance_interruption_behaviour = "stop"
+		instance_interruption_behavior = "stop"
 	}`)
 }