Fix disk_template OpInstSetParams parameter

This is not a required field, but rather an optional one; we add a new
parameter and use it instead.

Signed-off-by: Iustin Pop <iustin@google.com>
Reviewed-by: Helga Velroyen <helgav@google.com>

htools/Ganeti/OpCodes.hs

@@ -383,7 +383,7 @@ $(genOpCode "OpCode"
      , pInstBeParams
      , pRuntimeMem
      , pInstHvParams
-     , pDiskTemplate
+     , pOptDiskTemplate
      , pRemoteNode
      , pOsNameChange
      , pInstOsParams

htools/Ganeti/OpParams.hs

@@ -97,6 +97,7 @@ module Ganeti.OpParams
   , pAllowRuntimeChgs
   , pInstDisks
   , pDiskTemplate
+  , pOptDiskTemplate
   , pFileDriver
   , pFileStorageDir
   , pVgName
@@ -732,6 +733,13 @@ pInstDisks = renameField "instDisks" $ simpleField "disks" [t| [IDiskParams] |]
 pDiskTemplate :: Field
 pDiskTemplate = simpleField "disk_template" [t| DiskTemplate |]
 
+-- | Instance disk template.
+pOptDiskTemplate :: Field
+pOptDiskTemplate =
+  optionalField .
+  renameField "OptDiskTemplate" $
+  simpleField "disk_template" [t| DiskTemplate |]
+
 -- | File driver.
 pFileDriver :: Field
 pFileDriver = optionalField $ simpleField "file_driver" [t| FileDriver |]