Add basic controller code, initiating json rpc connection getting list of disks and memstats for now.

pkg/controller/client.go

@@ -0,0 +1,72 @@
+/*
+ * Minimalist Object Storage, (C) 2015 Minio, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package controller
+
+import (
+	"encoding/json"
+	"net/http"
+
+	jsonrpc "github.com/gorilla/rpc/v2/json"
+	"github.com/minio/minio/pkg/iodine"
+	"github.com/minio/minio/pkg/server/rpc"
+)
+
+// GetDisks get disks info of the server at given url
+func GetDisks(url string) ([]string, error) {
+	op := RPCOps{
+		Method:  "DiskInfo.Get",
+		Request: rpc.Args{Request: ""},
+	}
+	req, err := NewRequest(url, op, http.DefaultTransport)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	resp, err := req.Do()
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	defer resp.Body.Close()
+	var reply rpc.DiskInfoReply
+	if err := jsonrpc.DecodeClientResponse(resp.Body, &reply); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return reply.Disks, nil
+}
+
+// GetMemStats get system info of the server at given url
+func GetMemStats(url string) ([]byte, error) {
+	op := RPCOps{
+		Method:  "SysInfo.Get",
+		Request: rpc.Args{Request: ""},
+	}
+	req, err := NewRequest(url, op, http.DefaultTransport)
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	resp, err := req.Do()
+	if err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	defer resp.Body.Close()
+	var reply rpc.SysInfoReply
+	if err := jsonrpc.DecodeClientResponse(resp.Body, &reply); err != nil {
+		return nil, iodine.New(err, nil)
+	}
+	return json.MarshalIndent(reply, "", "\t")
+}
+
+// Add more functions here for many replies