From 2dd2567fa011032576a3c55f31c31a6b82c922bd Mon Sep 17 00:00:00 2001
From: Jason Zhang <jasonzhang9309@163.com>
Date: Mon, 14 Sep 2020 20:26:32 +0800
Subject: [PATCH] add compute_instace extend system disk support

---
 .../resource_huaweicloud_compute_instance.go  | 36 ++++++++++++++++++-
 website/docs/r/compute_instance.html.markdown |  4 ++-
 2 files changed, 38 insertions(+), 2 deletions(-)

diff --git a/huaweicloud/resource_huaweicloud_compute_instance.go b/huaweicloud/resource_huaweicloud_compute_instance.go
index 753c2d1e49..3419f90b8c 100644
--- a/huaweicloud/resource_huaweicloud_compute_instance.go
+++ b/huaweicloud/resource_huaweicloud_compute_instance.go
@@ -14,6 +14,7 @@ import (
 	"github.com/hashicorp/terraform-plugin-sdk/helper/schema"
 	"github.com/hashicorp/terraform-plugin-sdk/helper/validation"
 	"github.com/huaweicloud/golangsdk"
+	"github.com/huaweicloud/golangsdk/openstack/blockstorage/extensions/volumeactions"
 	"github.com/huaweicloud/golangsdk/openstack/blockstorage/v2/volumes"
 	"github.com/huaweicloud/golangsdk/openstack/common/tags"
 	"github.com/huaweicloud/golangsdk/openstack/compute/v2/extensions/availabilityzones"
@@ -254,7 +255,6 @@ func resourceComputeInstanceV2() *schema.Resource {
 			"system_disk_size": {
 				Type:          schema.TypeInt,
 				Optional:      true,
-				ForceNew:      true,
 				Computed:      true,
 				ConflictsWith: []string{"block_device", "metadata"},
 			},
@@ -961,6 +961,40 @@ func resourceComputeInstanceV2Update(d *schema.ResourceData, meta interface{}) e
 		}
 	}
 
+	if d.HasChange("system_disk_size") {
+		extendOpts := volumeactions.ExtendSizeOpts{
+			NewSize: d.Get("system_disk_size").(int),
+		}
+
+		blockStorageClient, err := config.blockStorageV2Client(GetRegion(d, config))
+
+		if err != nil {
+			return fmt.Errorf("Error creating HuaweiCloud block storage client: %s", err)
+		}
+
+		systemDiskID := d.Get("system_disk_id").(string)
+
+		err = volumeactions.ExtendSize(blockStorageClient, systemDiskID, extendOpts).ExtractErr()
+		if err != nil {
+			return fmt.Errorf("Error extending huaweicloud_compute_instance system disk %s size: %s", systemDiskID, err)
+		}
+
+		stateConf := &resource.StateChangeConf{
+			Pending:    []string{"extending"},
+			Target:     []string{"available", "in-use"},
+			Refresh:    VolumeV2StateRefreshFunc(blockStorageClient, systemDiskID),
+			Timeout:    d.Timeout(schema.TimeoutUpdate),
+			Delay:      10 * time.Second,
+			MinTimeout: 3 * time.Second,
+		}
+
+		_, err = stateConf.WaitForState()
+		if err != nil {
+			return fmt.Errorf(
+				"Error waiting for huaweicloud_compute_instance system disk %s to become ready: %s", systemDiskID, err)
+		}
+	}
+
 	return resourceComputeInstanceV2Read(d, meta)
 }
 
diff --git a/website/docs/r/compute_instance.html.markdown b/website/docs/r/compute_instance.html.markdown
index 632f0f0522..e86c56829d 100644
--- a/website/docs/r/compute_instance.html.markdown
+++ b/website/docs/r/compute_instance.html.markdown
@@ -229,7 +229,9 @@ The following arguments are supported:
 	* `co-p1`: high I/O(performance-optimized) disk type.
 	* `uh-l1`: ultra-high I/O(latency-optimized) disk type.
 
-* `system_disk_size` - (Optional) The system disk size in GB, The value range is 1 to 1024. Changing this creates a new server.
+* `system_disk_size` - (Optional) The system disk size in GB, The value range is 1 to 1024. Changing this parameter will update the disk. 
+    You can extend the disk by setting this parameter to a new value, which must be between current size and the max size(1024). 
+    Shrinking the disk is not supported.
 
 * `data_disks` - (Optional) An array of one or more data disks to attach to the
     instance. The data_disks object structure is documented below. Changing this