Add Profiler Admin API (#6463)

Two handlers are added to admin API to enable profiling and disable
profiling of a server in a standalone mode, or all nodes in the
distributed mode.

/minio/admin/profiling/start/{cpu,block,mem}:
  - Start profiling and return starting JSON results, e.g. one
    node is offline.

/minio/admin/profiling/download:
  - Stop the on-going profiling task
  - Stream a zip file which contains all profiling files that can
    be later inspected by go tool pprof

pkg/madmin/API.md

@@ -39,8 +39,8 @@ func main() {
 | Service operations         | Info operations  | Healing operations                    | Config operations         | Misc                                |
 |:----------------------------|:----------------------------|:--------------------------------------|:--------------------------|:------------------------------------|
 | [`ServiceStatus`](#ServiceStatus) | [`ServerInfo`](#ServerInfo) | [`Heal`](#Heal) | [`GetConfig`](#GetConfig) | [`SetCredentials`](#SetCredentials) |
-| [`ServiceSendAction`](#ServiceSendAction) | | | [`SetConfig`](#SetConfig) | |
-| | |            | [`GetConfigKeys`](#GetConfigKeys) |                                     |
+| [`ServiceSendAction`](#ServiceSendAction) | | | [`SetConfig`](#SetConfig) | [`StartProfiling`](#StartProfiling) |
+| | |            | [`GetConfigKeys`](#GetConfigKeys) | [`DownloadProfilingData`](#DownloadProfilingData) |
 | | |            | [`SetConfigKeys`](#SetConfigKeys) |                                     |
 
 
@@ -385,3 +385,56 @@ __Example__
     log.Println("New credentials successfully set.")
 
 ```
+
+<a name="StartProfiling"></a>
+### StartProfiling(profiler string) error
+Ask all nodes to start profiling using the specified profiler mode
+
+__Example__
+
+``` go
+    startProfilingResults, err = madmClnt.StartProfiling("cpu")
+    if err != nil {
+            log.Fatalln(err)
+    }
+    for _, result := range startProfilingResults {
+        if !result.Success {
+            log.Printf("Unable to start profiling on node `%s`, reason = `%s`\n", result.NodeName, result.Error)
+        } else {
+            log.Printf("Profiling successfully started on node `%s`\n", result.NodeName)
+        }
+    }
+
+```
+
+<a name="DownloadProfilingData"></a>
+### DownloadProfilingData() ([]byte, error)
+Download profiling data of all nodes in a zip format.
+
+__Example__
+
+``` go
+    profilingData, err := madmClnt.DownloadProfilingData()
+    if err != nil {
+            log.Fatalln(err)
+    }
+
+    profilingFile, err := os.Create("/tmp/profiling-data.zip")
+    if err != nil {
+            log.Fatal(err)
+    }
+
+    if _, err := io.Copy(profilingFile, profilingData); err != nil {
+            log.Fatal(err)
+    }
+
+    if err := profilingFile.Close(); err != nil {
+            log.Fatal(err)
+    }
+
+    if err := profilingData.Close(); err != nil {
+            log.Fatal(err)
+    }
+
+    log.Println("Profiling data successfully downloaded.")
+```

pkg/madmin/examples/profiling.go

@@ -0,0 +1,89 @@
+// +build ignore
+
+/*
+ * Minio Cloud Storage, (C) 2017 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 main
+
+import (
+	"io"
+	"log"
+	"os"
+	"time"
+
+	"github.com/minio/minio/pkg/madmin"
+)
+
+func main() {
+	// Note: YOUR-ACCESSKEYID, YOUR-SECRETACCESSKEY are
+	// dummy values, please replace them with original values.
+
+	// Note: YOUR-ACCESSKEYID, YOUR-SECRETACCESSKEY are
+	// dummy values, please replace them with original values.
+
+	// API requests are secure (HTTPS) if secure=true and insecure (HTTPS) otherwise.
+	// New returns an Minio Admin client object.
+	madmClnt, err := madmin.New("your-minio.example.com:9000", "YOUR-ACCESSKEYID", "YOUR-SECRETACCESSKEY", true)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	profiler := madmin.ProfilerCPU
+	log.Println("Starting " + profiler + " profiling..")
+
+	startResults, err := madmClnt.StartProfiling(profiler)
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	for _, result := range startResults {
+		if !result.Success {
+			log.Printf("Unable to start profiling on node `%s`, reason = `%s`\n", result.NodeName, result.Error)
+			continue
+		}
+		log.Printf("Profiling successfully started on node `%s`\n", result.NodeName)
+	}
+
+	sleep := time.Duration(10)
+	time.Sleep(time.Second * sleep)
+
+	log.Println("Stopping profiling..")
+
+	profilingData, err := madmClnt.DownloadProfilingData()
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	profilingFile, err := os.Create("/tmp/profiling-" + string(profiler) + ".zip")
+	if err != nil {
+		log.Fatal(err)
+	}
+
+	if _, err := io.Copy(profilingFile, profilingData); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := profilingFile.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	if err := profilingData.Close(); err != nil {
+		log.Fatal(err)
+	}
+
+	log.Println("Profiling files " + profilingFile.Name() + " successfully downloaded.")
+}

pkg/madmin/profiling-commands.go

@@ -0,0 +1,104 @@
+/*
+ * Minio Cloud Storage, (C) 2017, 2018 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 madmin
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"net/http"
+)
+
+// ProfilerType represents the profiler type
+// passed to the profiler subsystem, currently
+// it can be only "cpu", "mem" or "block"
+type ProfilerType string
+
+const (
+	// ProfilerCPU represents CPU profiler type
+	ProfilerCPU = ProfilerType("cpu")
+	// ProfilerMEM represents MEM profiler type
+	ProfilerMEM = ProfilerType("mem")
+	// ProfilerBlock represents Block profiler type
+	ProfilerBlock = ProfilerType("block")
+)
+
+// StartProfilingResult holds the result of starting
+// profiler result in a given node.
+type StartProfilingResult struct {
+	NodeName string `json:"nodeName"`
+	Success  bool   `json:"success"`
+	Error    string `json:"error"`
+}
+
+// StartProfiling makes an admin call to remotely start profiling on a standalone
+// server or the whole cluster in  case of a distributed setup.
+func (adm *AdminClient) StartProfiling(profiler ProfilerType) ([]StartProfilingResult, error) {
+	path := fmt.Sprintf("/v1/profiling/start/%s", profiler)
+	resp, err := adm.executeMethod("POST", requestData{
+		relPath: path,
+	})
+	defer closeResponse(resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, httpRespToErrorResponse(resp)
+	}
+
+	jsonResult, err := ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	var startResults []StartProfilingResult
+	err = json.Unmarshal(jsonResult, &startResults)
+	if err != nil {
+		return nil, err
+	}
+
+	return startResults, nil
+}
+
+// DownloadProfilingData makes an admin call to download profiling data of a standalone
+// server or of the whole cluster in  case of a distributed setup.
+func (adm *AdminClient) DownloadProfilingData() (io.ReadCloser, error) {
+	path := fmt.Sprintf("/v1/profiling/download")
+	resp, err := adm.executeMethod("GET", requestData{
+		relPath: path,
+	})
+
+	if err != nil {
+		closeResponse(resp)
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		closeResponse(resp)
+		return nil, httpRespToErrorResponse(resp)
+	}
+
+	if resp.Body == nil {
+		return nil, errors.New("body is nil")
+	}
+
+	return resp.Body, nil
+}