provider/aws: Only send iops when creating io1 devices. Fix docs (#12392)

builtin/providers/aws/resource_aws_instance.go

@@ -1034,11 +1034,16 @@ func readBlockDeviceMappingsFromConfig(
 
 			if v, ok := bd["volume_type"].(string); ok && v != "" {
 				ebs.VolumeType = aws.String(v)
-			}
-
+				if "io1" == strings.ToLower(v) {
+					// Condition: This parameter is required for requests to create io1
+					// volumes; it is not used in requests to create gp2, st1, sc1, or
+					// standard volumes.
+					// See: http://docs.aws.amazon.com/AWSEC2/latest/APIReference/API_EbsBlockDevice.html
 					if v, ok := bd["iops"].(int); ok && v > 0 {
 						ebs.Iops = aws.Int64(int64(v))
 					}
+				}
+			}
 
 			blockDevices = append(blockDevices, &ec2.BlockDeviceMapping{
 				DeviceName: aws.String(bd["device_name"].(string)),

builtin/providers/aws/resource_aws_instance_test.go

@@ -1060,7 +1060,6 @@ resource "aws_instance" "foo" {
 	root_block_device {
 		volume_type = "gp2"
 		volume_size = 11
-		iops = 330
 	}
 }
 `

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

@@ -102,7 +102,8 @@ The `root_block_device` mapping supports the following:
 * `volume_size` - (Optional) The size of the volume in gigabytes.
 * `iops` - (Optional) The amount of provisioned
   [IOPS](https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ebs-io-characteristics.html).
-  This must be set with a `volume_type` of `"io1"`.
+  This is only valid for `volume_type` of `"io1"`, and must be specified if
+  using that type
 * `delete_on_termination` - (Optional) Whether the volume should be destroyed
   on instance termination (Default: `true`).