provider/scaleway: improve volume attachment (hashicorp#10084)

* provider/scaleway: increase wait for server time

according to the scaleway community, shutdown/ startup might actually take an
hour. since a regular shutdown transfers data this is bound by the size of the
actual volumes in use.

https://community.online.net/t/solving-the-long-shutdown-boot-when-only-needed-to-attach-detach-a-volume/326

anyhow, 20 minutes seems quite optimistic, and we've seen some timeout errors in
the logs, too

* provider/scaleway: clear cache on volume attachment

the volume attachment errors quite often, and while I have no hard evidence
(yet) I guess it might be related to the cache that the official scaleway SDK
includes.

for now this is just a tiny experiment, clearing the cache when creating/
destroying volume attachments. let's see if this improves anything, really

* provider/scaleway: guard against attaching already attached volumes

* provider/scaleway: use cheaper instance types for tests

Scaleway bills by the hour and C2S costs much more than C1, since in the tests
we just spin up instances, to destroy them later on...

Author: nicolai86

builtin/providers/scaleway/helpers.go

@@ -84,7 +84,9 @@ func deleteStoppedServer(scaleway *api.ScalewayAPI, server *api.ScalewayServer)
 // the helpers.go file pulls in quite a lot dependencies, and they're just convenience wrappers anyway
 
 func waitForServerState(scaleway *api.ScalewayAPI, serverID, targetState string) error {
-	return resource.Retry(20*time.Minute, func() *resource.RetryError {
+	return resource.Retry(60*time.Minute, func() *resource.RetryError {
+		scaleway.ClearCache()
+
 		s, err := scaleway.GetServer(serverID)
 
 		if err != nil {

builtin/providers/scaleway/resource_scaleway_volume_attachment.go

@@ -30,10 +30,20 @@ func resourceScalewayVolumeAttachment() *schema.Resource {
 	}
 }
 
+var errVolumeAlreadyAttached = fmt.Errorf("Scaleway volume already attached")
+
 func resourceScalewayVolumeAttachmentCreate(d *schema.ResourceData, m interface{}) error {
 	scaleway := m.(*Client).scaleway
+	scaleway.ClearCache()
 
-	var startServerAgain = false
+	vol, err := scaleway.GetVolume(d.Get("volume").(string))
+	if err != nil {
+		return err
+	}
+	if vol.Server != nil {
+		log.Printf("[DEBUG] Scaleway volume %q already attached to %q.", vol.Identifier, vol.Server.Identifier)
+		return errVolumeAlreadyAttached
+	}
 
 	// guard against server shutdown/ startup race conditiond
 	serverID := d.Get("server").(string)
@@ -46,6 +56,7 @@ func resourceScalewayVolumeAttachmentCreate(d *schema.ResourceData, m interface{
 		return err
 	}
 
+	var startServerAgain = false
 	// volumes can only be modified when the server is powered off
 	if server.State != "stopped" {
 		startServerAgain = true
@@ -63,10 +74,6 @@ func resourceScalewayVolumeAttachmentCreate(d *schema.ResourceData, m interface{
 		volumes[i] = volume
 	}
 
-	vol, err := scaleway.GetVolume(d.Get("volume").(string))
-	if err != nil {
-		return err
-	}
 	volumes[fmt.Sprintf("%d", len(volumes)+1)] = *vol
 
 	// the API request requires most volume attributes to be unset to succeed
@@ -83,6 +90,8 @@ func resourceScalewayVolumeAttachmentCreate(d *schema.ResourceData, m interface{
 	}
 
 	if err := resource.Retry(5*time.Minute, func() *resource.RetryError {
+		scaleway.ClearCache()
+
 		var req = api.ScalewayServerPatchDefinition{
 			Volumes: &volumes,
 		}
@@ -121,6 +130,7 @@ func resourceScalewayVolumeAttachmentCreate(d *schema.ResourceData, m interface{
 
 func resourceScalewayVolumeAttachmentRead(d *schema.ResourceData, m interface{}) error {
 	scaleway := m.(*Client).scaleway
+	scaleway.ClearCache()
 
 	server, err := scaleway.GetServer(d.Get("server").(string))
 	if err != nil {
@@ -160,6 +170,8 @@ func resourceScalewayVolumeAttachmentRead(d *schema.ResourceData, m interface{})
 
 func resourceScalewayVolumeAttachmentDelete(d *schema.ResourceData, m interface{}) error {
 	scaleway := m.(*Client).scaleway
+	scaleway.ClearCache()
+
 	var startServerAgain = false
 
 	// guard against server shutdown/ startup race conditiond
@@ -204,6 +216,8 @@ func resourceScalewayVolumeAttachmentDelete(d *schema.ResourceData, m interface{
 	}
 
 	if err := resource.Retry(5*time.Minute, func() *resource.RetryError {
+		scaleway.ClearCache()
+
 		var req = api.ScalewayServerPatchDefinition{
 			Volumes: &volumes,
 		}

builtin/providers/scaleway/resource_scaleway_volume_attachment_test.go

@@ -70,24 +70,22 @@ func testAccCheckScalewayVolumeAttachmentExists(n string) resource.TestCheckFunc
 	}
 }
 
-var x86_64ImageIdentifier = "aecaed73-51a5-4439-a127-6d8229847145"
-
 var testAccCheckScalewayVolumeAttachmentConfig = fmt.Sprintf(`
 resource "scaleway_server" "base" {
   name = "test"
   # ubuntu 14.04
   image = "%s"
-  type = "C2S"
+  type = "C1"
   # state = "stopped"
 }
 
 resource "scaleway_volume" "test" {
   name = "test"
-  size_in_gb = 20
+  size_in_gb = 5
   type = "l_ssd"
 }
 
 resource "scaleway_volume_attachment" "test" {
   server = "${scaleway_server.base.id}"
   volume = "${scaleway_volume.test.id}"
-}`, x86_64ImageIdentifier)
+}`, armImageIdentifier)