provider/aws: Provide the option to skip_destroy on aws_volume_attachment (#9792)

* provider/aws: Provide the option to skip_destroy on
aws_volume_attachment

When you want to attach and detach pre-existing EBS volumes to an
instance, we would do that as follows:

```
resource "aws_instance" "web" {
	ami = "ami-21f78e11"
  availability_zone = "us-west-2a"
	instance_type = "t1.micro"
	tags {
		Name = "HelloWorld"
	}
}

data "aws_ebs_volume" "ebs_volume" {
  filter {
  	name = "size"
  	values = ["${aws_ebs_volume.example.size}"]
  }
  filter {
  	name = "availability-zone"
  	values = ["${aws_ebs_volume.example.availability_zone}"]
  }
  filter {
  	name = "tag:Name"
  	values = ["TestVolume"]
  }
}

resource "aws_volume_attachment" "ebs_att" {
  device_name = "/dev/sdh"
	volume_id = "${data.aws_ebs_volume.ebs_volume.id}"
	instance_id = "${aws_instance.web.id}"
	skip_destroy = true
}
```

The issue here is that when we run a terraform destroy command, the volume tries to get detached from a running instance and goes into a non-responsive state. We would have to force_destroy the volume at that point and risk losing any data on it.

This PR introduces the idea of `skip_destroy` on a volume attachment. tl;dr:

We want the volume to be detached from the instane when the instance itself has been destroyed. This way the normal shut procedures will happen and protect the disk for attachment to another instance

Volume Attachment Tests:

```
% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSVolumeAttachment_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/11/02 00:47:27 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSVolumeAttachment_ -timeout 120m
=== RUN   TestAccAWSVolumeAttachment_basic
--- PASS: TestAccAWSVolumeAttachment_basic (133.49s)
=== RUN   TestAccAWSVolumeAttachment_skipDestroy
--- PASS: TestAccAWSVolumeAttachment_skipDestroy (119.64s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/aws	253.158s
```

EBS Volume Tests:

```
% make testacc TEST=./builtin/providers/aws TESTARGS='-run=TestAccAWSEBSVolume_'
==> Checking that code complies with gofmt requirements...
go generate $(go list ./... | grep -v /terraform/vendor/)
2016/11/02 01:00:18 Generated command/internal_plugin_list.go
TF_ACC=1 go test ./builtin/providers/aws -v -run=TestAccAWSEBSVolume_ -timeout 120m
=== RUN   TestAccAWSEBSVolume_importBasic
--- PASS: TestAccAWSEBSVolume_importBasic (26.38s)
=== RUN   TestAccAWSEBSVolume_basic
--- PASS: TestAccAWSEBSVolume_basic (26.86s)
=== RUN   TestAccAWSEBSVolume_NoIops
--- PASS: TestAccAWSEBSVolume_NoIops (27.89s)
=== RUN   TestAccAWSEBSVolume_withTags
--- PASS: TestAccAWSEBSVolume_withTags (26.88s)
PASS
ok  	github.com/hashicorp/terraform/builtin/providers/aws	108.032s
```

* Update volume_attachment.html.markdown

builtin/providers/aws/resource_aws_ebs_volume.go

@@ -203,15 +203,27 @@ func resourceAwsEbsVolumeRead(d *schema.ResourceData, meta interface{}) error {
 func resourceAwsEbsVolumeDelete(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).ec2conn
 
-	request := &ec2.DeleteVolumeInput{
-		VolumeId: aws.String(d.Id()),
-	}
+	return resource.Retry(5*time.Minute, func() *resource.RetryError {
+		request := &ec2.DeleteVolumeInput{
+			VolumeId: aws.String(d.Id()),
+		}
+		_, err := conn.DeleteVolume(request)
+		if err == nil {
+			return nil
+		}
+
+		ebsErr, ok := err.(awserr.Error)
+		if ebsErr.Code() == "VolumeInUse" {
+			return resource.RetryableError(fmt.Errorf("EBS VolumeInUse - trying again while it detaches"))
+		}
+
+		if !ok {
+			return resource.NonRetryableError(err)
+		}
+
+		return resource.NonRetryableError(err)
+	})
 
-	_, err := conn.DeleteVolume(request)
-	if err != nil {
-		return fmt.Errorf("Error deleting EC2 volume %s: %s", d.Id(), err)
-	}
-	return nil
 }
 
 func readVolume(d *schema.ResourceData, volume *ec2.Volume) error {

builtin/providers/aws/resource_aws_volume_attachment.go

@@ -21,25 +21,30 @@ func resourceAwsVolumeAttachment() *schema.Resource {
 		Delete: resourceAwsVolumeAttachmentDelete,
 
 		Schema: map[string]*schema.Schema{
-			"device_name": &schema.Schema{
+			"device_name": {
 				Type:     schema.TypeString,
 				Required: true,
 				ForceNew: true,
 			},
 
-			"instance_id": &schema.Schema{
+			"instance_id": {
 				Type:     schema.TypeString,
 				Required: true,
 				ForceNew: true,
 			},
 
-			"volume_id": &schema.Schema{
+			"volume_id": {
 				Type:     schema.TypeString,
 				Required: true,
 				ForceNew: true,
 			},
 
-			"force_detach": &schema.Schema{
+			"force_detach": {
+				Type:     schema.TypeBool,
+				Optional: true,
+				Computed: true,
+			},
+			"skip_destroy": {
 				Type:     schema.TypeBool,
 				Optional: true,
 				Computed: true,
@@ -156,6 +161,12 @@ func resourceAwsVolumeAttachmentRead(d *schema.ResourceData, meta interface{}) e
 func resourceAwsVolumeAttachmentDelete(d *schema.ResourceData, meta interface{}) error {
 	conn := meta.(*AWSClient).ec2conn
 
+	if _, ok := d.GetOk("skip_destroy"); ok {
+		log.Printf("[INFO] Found skip_destroy to be true, removing attachment %q from state", d.Id())
+		d.SetId("")
+		return nil
+	}
+
 	vID := d.Get("volume_id").(string)
 	iID := d.Get("instance_id").(string)
 

builtin/providers/aws/resource_aws_volume_attachment_test.go

@@ -19,7 +19,7 @@ func TestAccAWSVolumeAttachment_basic(t *testing.T) {
 		Providers:    testAccProviders,
 		CheckDestroy: testAccCheckVolumeAttachmentDestroy,
 		Steps: []resource.TestStep{
-			resource.TestStep{
+			{
 				Config: testAccVolumeAttachmentConfig,
 				Check: resource.ComposeTestCheckFunc(
 					resource.TestCheckResourceAttr(
@@ -36,6 +36,32 @@ func TestAccAWSVolumeAttachment_basic(t *testing.T) {
 	})
 }
 
+func TestAccAWSVolumeAttachment_skipDestroy(t *testing.T) {
+	var i ec2.Instance
+	var v ec2.Volume
+
+	resource.Test(t, resource.TestCase{
+		PreCheck:     func() { testAccPreCheck(t) },
+		Providers:    testAccProviders,
+		CheckDestroy: testAccCheckVolumeAttachmentDestroy,
+		Steps: []resource.TestStep{
+			{
+				Config: testAccVolumeAttachmentConfigSkipDestroy,
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr(
+						"aws_volume_attachment.ebs_att", "device_name", "/dev/sdh"),
+					testAccCheckInstanceExists(
+						"aws_instance.web", &i),
+					testAccCheckVolumeExists(
+						"aws_ebs_volume.example", &v),
+					testAccCheckVolumeAttachmentExists(
+						"aws_volume_attachment.ebs_att", &i, &v),
+				),
+			},
+		},
+	})
+}
+
 func testAccCheckVolumeAttachmentExists(n string, i *ec2.Instance, v *ec2.Volume) resource.TestCheckFunc {
 	return func(s *terraform.State) error {
 		rs, ok := s.RootModule().Resources[n]
@@ -91,3 +117,44 @@ resource "aws_volume_attachment" "ebs_att" {
 	instance_id = "${aws_instance.web.id}"
 }
 `
+
+const testAccVolumeAttachmentConfigSkipDestroy = `
+resource "aws_instance" "web" {
+	ami = "ami-21f78e11"
+  	availability_zone = "us-west-2a"
+	instance_type = "t1.micro"
+	tags {
+		Name = "HelloWorld"
+	}
+}
+
+resource "aws_ebs_volume" "example" {
+  	availability_zone = "us-west-2a"
+	size = 1
+	tags {
+		Name = "TestVolume"
+	}
+}
+
+data "aws_ebs_volume" "ebs_volume" {
+    filter {
+	name = "size"
+	values = ["${aws_ebs_volume.example.size}"]
+    }
+    filter {
+	name = "availability-zone"
+	values = ["${aws_ebs_volume.example.availability_zone}"]
+    }
+    filter {
+	name = "tag:Name"
+	values = ["TestVolume"]
+    }
+}
+
+resource "aws_volume_attachment" "ebs_att" {
+  	device_name = "/dev/sdh"
+	volume_id = "${data.aws_ebs_volume.ebs_volume.id}"
+	instance_id = "${aws_instance.web.id}"
+	skip_destroy = true
+}
+`

website/source/docs/providers/aws/r/volume_attachment.html.markdown

@@ -49,6 +49,11 @@ example, `/dev/sdh` or `xvdh`)
 volume to detach. Useful if previous attempts failed, but use this option only 
 as a last resort, as this can result in **data loss**. See 
 [Detaching an Amazon EBS Volume from an Instance][1] for more information.
+* `skip_destroy` - (Optional, Boolean) Set this to true if you do not wish 
+to detach the volume from the instance to which it is attached at destroy 
+time, and instead just remove the attachment from Terraform state. This is 
+useful when destroying an instance which has volumes created by some other 
+means attached.
 
 ## Attributes Reference