Allow modifying volume topology

Author: iltyty

csi.proto

@@ -111,6 +111,12 @@ service Controller {
     returns (ControllerModifyVolumeResponse) {
         option (alpha_method) = true;
     }
+
+  rpc ControllerModifyVolumeTopology (
+        ControllerModifyVolumeTopologyRequest)
+    returns (ControllerModifyVolumeTopologyResponse) {
+        option (alpha_method) = true;
+    }
 }
 
 service GroupController {
@@ -1047,6 +1053,52 @@ message ControllerModifyVolumeResponse {
   option (alpha_message) = true;
 }
 
+message ControllerModifyVolumeTopologyRequest {
+  option (alpha_message) = true;
+
+  // Container identity information for the existing volume.
+  // This field is REQUIRED
+  string volume_id = 1;
+
+  // Secrets required by plugin to complete modify volume topology
+  // request.
+  // This field is OPTIONAL. Refer to the `Secrets Requirements`
+  // section on how to use this field.
+  map<string, string> secrets = 2 [(csi_secret) = true];
+
+  // Plugin specific volume attributes to mutate, passed in as 
+  // opaque key-value pairs. 
+  // This field is REQUIRED. The Plugin is responsible for
+  // parsing and validating these parameters. COs will treat these
+  // as opaque. The CO SHOULD specify the intended values of all mutable
+  // parameters it intends to modify. SPs MUST NOT modify volumes based
+  // on the absence of keys, only keys that are specified should result
+  // in modifications to the volume.
+  map<string, string> mutable_parameters = 3;
+}
+
+message ControllerModifyVolumeTopologyResponse {
+  option (alpha_message) = true;
+
+  // Specifies where (regions, zones, racks, etc.) the modified
+  // volume is accessible from.
+  // A plugin that returns this field MUST also set the
+  // VOLUME_ACCESSIBILITY_CONSTRAINTS plugin capability.
+  // The SP MAY specify multiple topologies to indicate the volume is
+  // accessible from multiple locations.
+  // COs MAY use this information along with the topology information
+  // returned by NodeGetInfo to ensure that a given volume is accessible
+  // from a given node when scheduling workloads.
+  repeated Topology accessible_topology = 1;
+
+  // Indicates whether the modification is still in progress.
+  // SP MAY set in_progress to update the accessible_topology
+  // before the modification finishes to reduce possible race
+  // conditions.
+  // COs SHOULD retry the request if in_progress is set to true,
+  // until in_progress is set to false.
+  bool in_progress = 2;
+}
 message GetCapacityRequest {
   // If specified, the Plugin SHALL report the capacity of the storage
   // that can be used to provision volumes that satisfy ALL of the
@@ -1194,6 +1246,10 @@ message ControllerServiceCapability {
       // Indicates the SP supports the GetSnapshot RPC.
       // This enables COs to fetch an existing snapshot.
       GET_SNAPSHOT = 15 [(alpha_enum_value) = true];
+
+      // Indicates the SP supports modifying volume topology.
+      // See ControllerModifyVolumeTopology for details.
+      MODIFY_VOLUME_TOPOLOGY = 16 [(alpha_enum_value) = true];
     }
 
     Type type = 1;