*: Change etcdserver API to support raft learner

- Added isLearner flag to MemberAddRequest in Cluster API.
- Added isLearner field to StatusResponse in Maintenance API.
- Added MemberPromote rpc to Cluster API.

Documentation/dev-guide/api_reference_v3.md

@@ -37,6 +37,7 @@ This is a generated documentation. Please read the proto files for more.
 | MemberRemove | MemberRemoveRequest | MemberRemoveResponse | MemberRemove removes an existing member from the cluster. |
 | MemberUpdate | MemberUpdateRequest | MemberUpdateResponse | MemberUpdate updates the member configuration. |
 | MemberList | MemberListRequest | MemberListResponse | MemberList lists all the members in the cluster. |
+| MemberPromote | MemberPromoteRequest | MemberPromoteResponse | MemberPromote promotes a member from raft learner (non-voting) to raft voting member. |
 
 
 
@@ -609,6 +610,7 @@ Empty field.
 | name | name is the human-readable name of the member. If the member is not started, the name will be an empty string. | string |
 | peerURLs | peerURLs is the list of URLs the member exposes to the cluster for communication. | (slice of) string |
 | clientURLs | clientURLs is the list of URLs the member exposes to clients for communication. If the member is not started, clientURLs will be empty. | (slice of) string |
+| isLearner | isLearner indicates if the member is raft learner. | bool |
 
 
 
@@ -617,6 +619,7 @@ Empty field.
 | Field | Description | Type |
 | ----- | ----------- | ---- |
 | peerURLs | peerURLs is the list of URLs the added member will use to communicate with the cluster. | (slice of) string |
+| isLearner | isLearner indicates if the added member is raft learner. | bool |
 
 
 
@@ -645,6 +648,23 @@ Empty field.
 
 
 
+##### message `MemberPromoteRequest` (etcdserver/etcdserverpb/rpc.proto)
+
+| Field | Description | Type |
+| ----- | ----------- | ---- |
+| ID | ID is the member ID of the member to promote. | uint64 |
+
+
+
+##### message `MemberPromoteResponse` (etcdserver/etcdserverpb/rpc.proto)
+
+| Field | Description | Type |
+| ----- | ----------- | ---- |
+| header |  | ResponseHeader |
+| members | members is a list of all members after promoting the member. | (slice of) Member |
+
+
+
 ##### message `MemberRemoveRequest` (etcdserver/etcdserverpb/rpc.proto)
 
 | Field | Description | Type |
@@ -819,6 +839,7 @@ Empty field.
 | raftAppliedIndex | raftAppliedIndex is the current raft applied index of the responding member. | uint64 |
 | errors | errors contains alarm/health information and status. | (slice of) string |
 | dbSizeInUse | dbSizeInUse is the size of the backend database logically in use, in bytes, of the responding member. | int64 |
+| isLearner | isLearner indicates if the member is raft learner. | bool |
 
 
 

Documentation/dev-guide/apispec/swagger/rpc.swagger.json

@@ -501,6 +501,33 @@
         }
       }
     },
+    "/v3/cluster/member/promote": {
+      "post": {
+        "tags": [
+          "Cluster"
+        ],
+        "summary": "MemberPromote promotes a member from raft learner (non-voting) to raft voting member.",
+        "operationId": "MemberPromote",
+        "parameters": [
+          {
+            "name": "body",
+            "in": "body",
+            "required": true,
+            "schema": {
+              "$ref": "#/definitions/etcdserverpbMemberPromoteRequest"
+            }
+          }
+        ],
+        "responses": {
+          "200": {
+            "description": "A successful response.",
+            "schema": {
+              "$ref": "#/definitions/etcdserverpbMemberPromoteResponse"
+            }
+          }
+        }
+      }
+    },
     "/v3/cluster/member/remove": {
       "post": {
         "tags": [
@@ -820,7 +847,7 @@
           "200": {
             "description": "A successful response.(streaming responses)",
             "schema": {
-              "$ref": "#/definitions/etcdserverpbLeaseKeepAliveResponse"
+              "$ref": "#/x-stream-definitions/etcdserverpbLeaseKeepAliveResponse"
             }
           }
         }
@@ -1009,7 +1036,7 @@
           "200": {
             "description": "A successful response.(streaming responses)",
             "schema": {
-              "$ref": "#/definitions/etcdserverpbSnapshotResponse"
+              "$ref": "#/x-stream-definitions/etcdserverpbSnapshotResponse"
             }
           }
         }
@@ -1091,7 +1118,7 @@
           "200": {
             "description": "A successful response.(streaming responses)",
             "schema": {
-              "$ref": "#/definitions/etcdserverpbWatchResponse"
+              "$ref": "#/x-stream-definitions/etcdserverpbWatchResponse"
             }
           }
         }
@@ -1882,6 +1909,11 @@
             "type": "string"
           }
         },
+        "isLearner": {
+          "description": "isLearner indicates if the member is raft learner.",
+          "type": "boolean",
+          "format": "boolean"
+        },
         "name": {
           "description": "name is the human-readable name of the member. If the member is not started, the name will be an empty string.",
           "type": "string"
@@ -1898,6 +1930,11 @@
     "etcdserverpbMemberAddRequest": {
       "type": "object",
       "properties": {
+        "isLearner": {
+          "description": "isLearner indicates if the added member is raft learner.",
+          "type": "boolean",
+          "format": "boolean"
+        },
         "peerURLs": {
           "description": "peerURLs is the list of URLs the added member will use to communicate with the cluster.",
           "type": "array",
@@ -1944,6 +1981,31 @@
         }
       }
     },
+    "etcdserverpbMemberPromoteRequest": {
+      "type": "object",
+      "properties": {
+        "ID": {
+          "description": "ID is the member ID of the member to promote.",
+          "type": "string",
+          "format": "uint64"
+        }
+      }
+    },
+    "etcdserverpbMemberPromoteResponse": {
+      "type": "object",
+      "properties": {
+        "header": {
+          "$ref": "#/definitions/etcdserverpbResponseHeader"
+        },
+        "members": {
+          "description": "members is a list of all members after promoting the member.",
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/etcdserverpbMember"
+          }
+        }
+      }
+    },
     "etcdserverpbMemberRemoveRequest": {
       "type": "object",
       "properties": {
@@ -2266,6 +2328,11 @@
         "header": {
           "$ref": "#/definitions/etcdserverpbResponseHeader"
         },
+        "isLearner": {
+          "description": "isLearner indicates if the member is raft learner.",
+          "type": "boolean",
+          "format": "boolean"
+        },
         "leader": {
           "description": "leader is the member ID which the responding member believes is the current leader.",
           "type": "string",
@@ -2508,6 +2575,43 @@
           "format": "int64"
         }
       }
+    },
+    "protobufAny": {
+      "type": "object",
+      "properties": {
+        "type_url": {
+          "type": "string"
+        },
+        "value": {
+          "type": "string",
+          "format": "byte"
+        }
+      }
+    },
+    "runtimeStreamError": {
+      "type": "object",
+      "properties": {
+        "details": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/protobufAny"
+          }
+        },
+        "grpc_code": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "http_code": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "http_status": {
+          "type": "string"
+        },
+        "message": {
+          "type": "string"
+        }
+      }
     }
   },
   "securityDefinitions": {
@@ -2521,5 +2625,43 @@
     {
       "ApiKey": []
     }
-  ]
+  ],
+  "x-stream-definitions": {
+    "etcdserverpbLeaseKeepAliveResponse": {
+      "properties": {
+        "error": {
+          "$ref": "#/definitions/runtimeStreamError"
+        },
+        "result": {
+          "$ref": "#/definitions/etcdserverpbLeaseKeepAliveResponse"
+        }
+      },
+      "title": "Stream result of etcdserverpbLeaseKeepAliveResponse",
+      "type": "object"
+    },
+    "etcdserverpbSnapshotResponse": {
+      "properties": {
+        "error": {
+          "$ref": "#/definitions/runtimeStreamError"
+        },
+        "result": {
+          "$ref": "#/definitions/etcdserverpbSnapshotResponse"
+        }
+      },
+      "title": "Stream result of etcdserverpbSnapshotResponse",
+      "type": "object"
+    },
+    "etcdserverpbWatchResponse": {
+      "properties": {
+        "error": {
+          "$ref": "#/definitions/runtimeStreamError"
+        },
+        "result": {
+          "$ref": "#/definitions/etcdserverpbWatchResponse"
+        }
+      },
+      "title": "Stream result of etcdserverpbWatchResponse",
+      "type": "object"
+    }
+  }
 }

Documentation/dev-guide/apispec/swagger/v3election.swagger.json

@@ -77,7 +77,7 @@
           "200": {
             "description": "A successful response.(streaming responses)",
             "schema": {
-              "$ref": "#/definitions/v3electionpbLeaderResponse"
+              "$ref": "#/x-stream-definitions/v3electionpbLeaderResponse"
             }
           }
         },
@@ -212,6 +212,43 @@
         }
       }
     },
+    "protobufAny": {
+      "type": "object",
+      "properties": {
+        "type_url": {
+          "type": "string"
+        },
+        "value": {
+          "type": "string",
+          "format": "byte"
+        }
+      }
+    },
+    "runtimeStreamError": {
+      "type": "object",
+      "properties": {
+        "grpc_code": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "http_code": {
+          "type": "integer",
+          "format": "int32"
+        },
+        "message": {
+          "type": "string"
+        },
+        "http_status": {
+          "type": "string"
+        },
+        "details": {
+          "type": "array",
+          "items": {
+            "$ref": "#/definitions/protobufAny"
+          }
+        }
+      }
+    },
     "v3electionpbCampaignRequest": {
       "type": "object",
       "properties": {
@@ -330,5 +367,19 @@
         }
       }
     }
+  },
+  "x-stream-definitions": {
+    "v3electionpbLeaderResponse": {
+      "type": "object",
+      "properties": {
+        "result": {
+          "$ref": "#/definitions/v3electionpbLeaderResponse"
+        },
+        "error": {
+          "$ref": "#/definitions/runtimeStreamError"
+        }
+      },
+      "title": "Stream result of v3electionpbLeaderResponse"
+    }
   }
 }

etcdserver/etcdserverpb/etcdserver.pb.go

@@ -64,6 +64,8 @@
 		MemberUpdateResponse
 		MemberListRequest
 		MemberListResponse
+		MemberPromoteRequest
+		MemberPromoteResponse
 		DefragmentRequest
 		DefragmentResponse
 		MoveLeaderRequest

etcdserver/etcdserverpb/gw/rpc.pb.gw.go

@@ -341,6 +341,19 @@ func request_Cluster_MemberList_0(ctx context.Context, marshaler runtime.Marshal
 
 }
 
+func request_Cluster_MemberPromote_0(ctx context.Context, marshaler runtime.Marshaler, client etcdserverpb.ClusterClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
+	var protoReq etcdserverpb.MemberPromoteRequest
+	var metadata runtime.ServerMetadata
+
+	if err := marshaler.NewDecoder(req.Body).Decode(&protoReq); err != nil && err != io.EOF {
+		return nil, metadata, status.Errorf(codes.InvalidArgument, "%v", err)
+	}
+
+	msg, err := client.MemberPromote(ctx, &protoReq, grpc.Header(&metadata.HeaderMD), grpc.Trailer(&metadata.TrailerMD))
+	return msg, metadata, err
+
+}
+
 func request_Maintenance_Alarm_0(ctx context.Context, marshaler runtime.Marshaler, client etcdserverpb.MaintenanceClient, req *http.Request, pathParams map[string]string) (proto.Message, runtime.ServerMetadata, error) {
 	var protoReq etcdserverpb.AlarmRequest
 	var metadata runtime.ServerMetadata
@@ -1399,6 +1412,35 @@ func RegisterClusterHandlerClient(ctx context.Context, mux *runtime.ServeMux, cl
 
 	})
 
+	mux.Handle("POST", pattern_Cluster_MemberPromote_0, func(w http.ResponseWriter, req *http.Request, pathParams map[string]string) {
+		ctx, cancel := context.WithCancel(req.Context())
+		defer cancel()
+		if cn, ok := w.(http.CloseNotifier); ok {
+			go func(done <-chan struct{}, closed <-chan bool) {
+				select {
+				case <-done:
+				case <-closed:
+					cancel()
+				}
+			}(ctx.Done(), cn.CloseNotify())
+		}
+		inboundMarshaler, outboundMarshaler := runtime.MarshalerForRequest(mux, req)
+		rctx, err := runtime.AnnotateContext(ctx, mux, req)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+		resp, md, err := request_Cluster_MemberPromote_0(rctx, inboundMarshaler, client, req, pathParams)
+		ctx = runtime.NewServerMetadataContext(ctx, md)
+		if err != nil {
+			runtime.HTTPError(ctx, mux, outboundMarshaler, w, req, err)
+			return
+		}
+
+		forward_Cluster_MemberPromote_0(ctx, mux, outboundMarshaler, w, req, resp, mux.GetForwardResponseOptions()...)
+
+	})
+
 	return nil
 }
 
@@ -1410,6 +1452,8 @@ var (
 	pattern_Cluster_MemberUpdate_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2, 2, 3}, []string{"v3", "cluster", "member", "update"}, ""))
 
 	pattern_Cluster_MemberList_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2, 2, 3}, []string{"v3", "cluster", "member", "list"}, ""))
+
+	pattern_Cluster_MemberPromote_0 = runtime.MustPattern(runtime.NewPattern(1, []int{2, 0, 2, 1, 2, 2, 2, 3}, []string{"v3", "cluster", "member", "promote"}, ""))
 )
 
 var (
@@ -1420,6 +1464,8 @@ var (
 	forward_Cluster_MemberUpdate_0 = runtime.ForwardResponseMessage
 
 	forward_Cluster_MemberList_0 = runtime.ForwardResponseMessage
+
+	forward_Cluster_MemberPromote_0 = runtime.ForwardResponseMessage
 )
 
 // RegisterMaintenanceHandlerFromEndpoint is same as RegisterMaintenanceHandler but

etcdserver/etcdserverpb/rpc.proto

@@ -165,6 +165,14 @@ service Cluster {
         body: "*"
     };
   }
+
+  // MemberPromote promotes a member from raft learner (non-voting) to raft voting member.
+  rpc MemberPromote(MemberPromoteRequest) returns (MemberPromoteResponse) {
+      option (google.api.http) = {
+        post: "/v3/cluster/member/promote"
+        body: "*"
+    };
+  }
 }
 
 service Maintenance {
@@ -846,11 +854,15 @@ message Member {
   repeated string peerURLs = 3;
   // clientURLs is the list of URLs the member exposes to clients for communication. If the member is not started, clientURLs will be empty.
   repeated string clientURLs = 4;
+  // isLearner indicates if the member is raft learner.
+  bool isLearner = 5;
 }
 
 message MemberAddRequest {
   // peerURLs is the list of URLs the added member will use to communicate with the cluster.
   repeated string peerURLs = 1;
+  // isLearner indicates if the added member is raft learner.
+  bool isLearner = 2;
 }
 
 message MemberAddResponse {
@@ -894,6 +906,17 @@ message MemberListResponse {
   repeated Member members = 2;
 }
 
+message MemberPromoteRequest {
+  // ID is the member ID of the member to promote.
+  uint64 ID = 1;
+}
+
+message MemberPromoteResponse {
+  ResponseHeader header = 1;
+  // members is a list of all members after promoting the member.
+  repeated Member members = 2;
+}
+
 message DefragmentRequest {
 }
 
@@ -967,6 +990,8 @@ message StatusResponse {
   repeated string errors = 8;
   // dbSizeInUse is the size of the backend database logically in use, in bytes, of the responding member.
   int64 dbSizeInUse = 9;
+  // isLearner indicates if the member is raft learner.
+  bool isLearner = 10;
 }
 
 message AuthEnableRequest {