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providers/aws: add root_block_device to aws_instance
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AWS provides a single `BlockDeviceMapping` to manage three different
kinds of block devices:

 (a) The root volume
 (b) Ephemeral storage
 (c) Additional EBS volumes

Each of these types has slightly different semantics [1].

(a) The root volume is defined by the AMI; it can only be customized
with `volume_size`, `volume_type`, and `delete_on_termination`.

(b) Ephemeral storage is made available based on instance type [2]. It's
attached automatically if _no_ block device mappings are specified, and
must otherwise be defined with block device mapping entries that contain
only DeviceName set to a device like "/dev/sdX" and VirtualName set to
"ephemeralN".

(c) Additional EBS volumes are controlled by mappings that omit
`virtual_name` and can specify `volume_size`, `volume_type`,
`delete_on_termination`, `snapshot_id`, and `encryption`.

After deciding to ignore root block devices to fix hashicorp#859, we had users
with configurations that were attempting to manage the root block device chime
in on hashicorp#913.

Terraform does not have the primitives to be able to properly handle a
single collection of resources that is partially managed and partially
computed, so our strategy here is to break out logical sub-resources for
Terraform and hide the BlockDeviceMapping inside the provider
implementation.

Now (a) is supported by the `root_block_device` sub-resource, and (b)
and (c) are still both merged together under `block_device`, though I
have yet to see ephemeral block devices working properly.

Looking into possibly separating out `ephemeral_block_device` and
`ebs_block_device` sub-resources as well, which seem like the logical
next step. We'll wait until the next big release for this, though, since
it will break backcompat.

[1] http://bit.ly/ec2bdmap
[2] http://bit.ly/instancestorebytype

Fixes hashicorp#913
Refs hashicorp#858
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@phinze
phinze authored and Yahya Poonawala committed Mar 13, 2015
1 parent ce9a6be commit 40efd53
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Showing 3 changed files with 122 additions and 33 deletions.
117 changes: 89 additions & 28 deletions builtin/providers/aws/resource_aws_instance.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -190,6 +190,50 @@ func resourceAwsInstance() *schema.Resource {
},
Set: resourceAwsInstanceBlockDevicesHash,
},

"root_block_device": &schema.Schema{
// TODO: This is a list because we don't support singleton
// sub-resources today. We'll enforce that the list only ever has
// length zero or one below. When TF gains support for
// sub-resources this can be converted.
Type: schema.TypeList,
Optional: true,
Computed: true,
Elem: &schema.Resource{
// "You can only modify the volume size, volume type, and Delete on
// Termination flag on the block device mapping entry for the root
// device volume." - bit.ly/ec2bdmap
Schema: map[string]*schema.Schema{
"delete_on_termination": &schema.Schema{
Type: schema.TypeBool,
Optional: true,
Default: true,
ForceNew: true,
},

"device_name": &schema.Schema{
Type: schema.TypeString,
Optional: true,
ForceNew: true,
Default: "/dev/sda1",
},

"volume_size": &schema.Schema{
Type: schema.TypeInt,
Optional: true,
Computed: true,
ForceNew: true,
},

"volume_type": &schema.Schema{
Type: schema.TypeString,
Optional: true,
Computed: true,
ForceNew: true,
},
},
},
},
},
}
}
Expand Down Expand Up @@ -238,19 +282,36 @@ func resourceAwsInstanceCreate(d *schema.ResourceData, meta interface{}) error {
}
}

blockDevices := make([]interface{}, 0)

if v := d.Get("block_device"); v != nil {
vs := v.(*schema.Set).List()
if len(vs) > 0 {
runOpts.BlockDevices = make([]ec2.BlockDeviceMapping, len(vs))
for i, v := range vs {
bd := v.(map[string]interface{})
runOpts.BlockDevices[i].DeviceName = bd["device_name"].(string)
runOpts.BlockDevices[i].VirtualName = bd["virtual_name"].(string)
runOpts.BlockDevices[i].SnapshotId = bd["snapshot_id"].(string)
runOpts.BlockDevices[i].VolumeType = bd["volume_type"].(string)
runOpts.BlockDevices[i].VolumeSize = int64(bd["volume_size"].(int))
runOpts.BlockDevices[i].DeleteOnTermination = bd["delete_on_termination"].(bool)
runOpts.BlockDevices[i].Encrypted = bd["encrypted"].(bool)
blockDevices = append(blockDevices, v.(*schema.Set).List()...)
}

if v := d.Get("root_block_device"); v != nil {
rootBlockDevices := v.([]interface{})
if len(rootBlockDevices) > 1 {
return fmt.Errorf("Cannot specify more than one root_block_device.")
}
blockDevices = append(blockDevices, rootBlockDevices...)
}

if len(blockDevices) > 0 {
runOpts.BlockDevices = make([]ec2.BlockDeviceMapping, len(blockDevices))
for i, v := range blockDevices {
bd := v.(map[string]interface{})
runOpts.BlockDevices[i].DeviceName = bd["device_name"].(string)
runOpts.BlockDevices[i].VolumeType = bd["volume_type"].(string)
runOpts.BlockDevices[i].VolumeSize = int64(bd["volume_size"].(int))
runOpts.BlockDevices[i].DeleteOnTermination = bd["delete_on_termination"].(bool)
if v, ok := bd["virtual_name"].(string); ok {
runOpts.BlockDevices[i].VirtualName = v
}
if v, ok := bd["snapshot_id"].(string); ok {
runOpts.BlockDevices[i].SnapshotId = v
}
if v, ok := bd["encrypted"].(bool); ok {
runOpts.BlockDevices[i].Encrypted = v
}
}
}
Expand Down Expand Up @@ -379,11 +440,6 @@ func resourceAwsInstanceRead(d *schema.ResourceData, meta interface{}) error {

blockDevices := make(map[string]ec2.BlockDevice)
for _, bd := range instance.BlockDevices {
// Skip root device; AWS attaches it automatically and terraform does not
// manage it
if bd.DeviceName == instance.RootDeviceName {
continue
}
blockDevices[bd.VolumeId] = bd
}

Expand All @@ -397,21 +453,26 @@ func resourceAwsInstanceRead(d *schema.ResourceData, meta interface{}) error {
return err
}

bds := make([]map[string]interface{}, len(volResp.Volumes))
for i, vol := range volResp.Volumes {
nonRootBlockDevices := make([]map[string]interface{}, 0)
for _, vol := range volResp.Volumes {
volSize, err := strconv.Atoi(vol.Size)
if err != nil {
return err
}
bds[i] = make(map[string]interface{})
bds[i]["device_name"] = blockDevices[vol.VolumeId].DeviceName
bds[i]["snapshot_id"] = vol.SnapshotId
bds[i]["volume_type"] = vol.VolumeType
bds[i]["volume_size"] = volSize
bds[i]["delete_on_termination"] = blockDevices[vol.VolumeId].DeleteOnTermination
bds[i]["encrypted"] = vol.Encrypted
blockDevice := make(map[string]interface{})
blockDevice["device_name"] = blockDevices[vol.VolumeId].DeviceName
blockDevice["snapshot_id"] = vol.SnapshotId
blockDevice["volume_type"] = vol.VolumeType
blockDevice["volume_size"] = volSize
blockDevice["delete_on_termination"] = blockDevices[vol.VolumeId].DeleteOnTermination
blockDevice["encrypted"] = vol.Encrypted
if blockDevice["device_name"] == instance.RootDeviceName {
d.Set("root_block_device", []interface{}{blockDevice})
} else {
nonRootBlockDevices = append(nonRootBlockDevices, blockDevice)
}
}
d.Set("block_device", bds)
d.Set("block_device", nonRootBlockDevices)

return nil
}
Expand All @@ -429,7 +490,7 @@ func resourceAwsInstanceUpdate(d *schema.ResourceData, meta interface{}) error {
}

if modify {
log.Printf("[INFO] Modifing instance %s: %#v", d.Id(), opts)
log.Printf("[INFO] Modifying instance %s: %#v", d.Id(), opts)
if _, err := ec2conn.ModifyInstance(d.Id(), opts); err != nil {
return err
}
Expand Down
27 changes: 22 additions & 5 deletions builtin/providers/aws/resource_aws_instance_test.go
View file
Original file line number Diff line number Diff line change
Expand Up @@ -66,7 +66,7 @@ func TestAccAWSInstance_normal(t *testing.T) {
})
}

func TestAccAWSInstance_blockDevicesCheck(t *testing.T) {
func TestAccAWSInstance_blockDevices(t *testing.T) {
var v ec2.Instance

testCheck := func() resource.TestCheckFunc {
Expand All @@ -78,6 +78,11 @@ func TestAccAWSInstance_blockDevicesCheck(t *testing.T) {
blockDevices[blockDevice.DeviceName] = blockDevice
}

// Check if the root block device exists.
if _, ok := blockDevices["/dev/sda1"]; !ok {
fmt.Errorf("block device doesn't exist: /dev/sda1")
}

// Check if the secondary block device exists.
if _, ok := blockDevices["/dev/sdb"]; !ok {
fmt.Errorf("block device doesn't exist: /dev/sdb")
Expand All @@ -97,11 +102,18 @@ func TestAccAWSInstance_blockDevicesCheck(t *testing.T) {
Check: resource.ComposeTestCheckFunc(
testAccCheckInstanceExists(
"aws_instance.foo", &v),
// though two block devices exist in EC2, terraform state should only
// have the one block device we created, as terraform does not manage
// the root device
resource.TestCheckResourceAttr(
"aws_instance.foo", "root_block_device.#", "1"),
resource.TestCheckResourceAttr(
"aws_instance.foo", "root_block_device.0.device_name", "/dev/sda1"),
resource.TestCheckResourceAttr(
"aws_instance.foo", "root_block_device.0.volume_size", "11"),
resource.TestCheckResourceAttr(
"aws_instance.foo", "block_device.#", "1"),
resource.TestCheckResourceAttr(
"aws_instance.foo", "block_device.172787947.device_name", "/dev/sdb"),
resource.TestCheckResourceAttr(
"aws_instance.foo", "block_device.172787947.volume_size", "9"),
testCheck(),
),
},
Expand Down Expand Up @@ -359,10 +371,15 @@ resource "aws_instance" "foo" {
# us-west-2
ami = "ami-55a7ea65"
instance_type = "m1.small"
root_block_device {
device_name = "/dev/sda1"
volume_type = "gp2"
volume_size = 11
}
block_device {
device_name = "/dev/sdb"
volume_type = "gp2"
volume_size = 10
volume_size = 9
}
}
`
Expand Down
11 changes: 11 additions & 0 deletions website/source/docs/providers/aws/r/instance.html.markdown
View file
Original file line number Diff line number Diff line change
Expand Up @@ -48,6 +48,8 @@ The following arguments are supported:
launch the instance with.
* `tags` - (Optional) A mapping of tags to assign to the resource.
* `block_device` - (Optional) A list of block devices to add. Their keys are documented below.
* `root_block_device` - (Optional) Customize details about the root block
device of the instance. Available keys are documented below.

Each `block_device` supports the following:

Expand All @@ -59,6 +61,15 @@ Each `block_device` supports the following:
* `delete_on_termination` - (Optional) Should the volume be destroyed on instance termination (defaults true).
* `encrypted` - (Optional) Should encryption be enabled (defaults false).

The `root_block_device` mapping supports the following:

* `device_name` - The name of the root device on the target instance. Must
match the root device as defined in the AMI. Defaults to "/dev/sda1", which
is the typical root volume for Linux instances.
* `volume_type` - (Optional) The type of volume. Can be standard, gp2, or io1. Defaults to standard.
* `volume_size` - (Optional) The size of the volume in gigabytes.
* `delete_on_termination` - (Optional) Should the volume be destroyed on instance termination (defaults true).

## Attributes Reference

The following attributes are exported:
Expand Down

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