Add admin get/set config keys API (#6113)

This PR adds two new admin APIs in Minio server and madmin package:
- GetConfigKeys(keys []string) ([]byte, error)
- SetConfigKeys(params map[string]string) (err error)

A key is a path in Minio configuration file, (e.g. notify.webhook.1)

The user will always send a string value when setting it in the config file,
the API will know how to convert the value to the appropriate type. The user
is also able to set a raw json.

Before setting a new config, Minio will validate all fields and try to connect
to notification targets if available.

pkg/madmin/API.md

@@ -40,6 +40,8 @@ func main() {
 |:----------------------------|:----------------------------|:--------------------------------------|:--------------------------|:------------------------------------|
 | [`ServiceStatus`](#ServiceStatus) | [`ServerInfo`](#ServerInfo) | [`Heal`](#Heal) | [`GetConfig`](#GetConfig) | [`SetCredentials`](#SetCredentials) |
 | [`ServiceSendAction`](#ServiceSendAction) | | | [`SetConfig`](#SetConfig) | |
+| | |            | [`GetConfigKeys`](#GetConfigKeys) |                                     |
+| | |            | [`SetConfigKeys`](#SetConfigKeys) |                                     |
 
 
 ## 1. Constructor
@@ -326,6 +328,47 @@ __Example__
     log.Println("SetConfig: ", string(buf.Bytes()))
 ```
 
+<a name="GetConfigKeys"></a>
+### GetConfigKeys(keys []string) ([]byte, error)
+Get a json document which contains a set of keys and their values from config.json.
+
+__Example__
+
+``` go
+    configBytes, err := madmClnt.GetConfigKeys([]string{"version", "notify.amqp.1"})
+    if err != nil {
+        log.Fatalf("failed due to: %v", err)
+    }
+
+    // Pretty-print config received as json.
+    var buf bytes.Buffer
+    err = json.Indent(buf, configBytes, "", "\t")
+    if err != nil {
+        log.Fatalf("failed due to: %v", err)
+    }
+
+    log.Println("config received successfully: ", string(buf.Bytes()))
+```
+
+
+<a name="SetConfigKeys"></a>
+### SetConfigKeys(params map[string]string) error
+Set a set of keys and values for Minio server or distributed setup and restart the Minio
+server for the new configuration changes to take effect.
+
+__Example__
+
+``` go
+    err := madmClnt.SetConfigKeys(map[string]string{"notify.webhook.1": "{\"enable\": true, \"endpoint\": \"http://example.com/api\"}"})
+    if err != nil {
+        log.Fatalf("failed due to: %v", err)
+    }
+
+    log.Println("New configuration successfully set")
+```
+
+
+
 ## 8. Misc operations
 
 <a name="SetCredentials"></a>

pkg/madmin/config-commands.go

@@ -20,12 +20,14 @@ package madmin
 import (
 	"bytes"
 	"crypto/rand"
+	"encoding/base64"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
 	"net/http"
+	"net/url"
 
 	"github.com/minio/minio/pkg/quick"
 	"github.com/minio/sio"
@@ -90,6 +92,36 @@ func (adm *AdminClient) GetConfig() ([]byte, error) {
 	return DecryptServerConfigData(adm.secretAccessKey, resp.Body)
 }
 
+// GetConfigKeys - returns partial json or json value from config.json of a minio setup.
+func (adm *AdminClient) GetConfigKeys(keys []string) ([]byte, error) {
+	// No TLS?
+	if !adm.secure {
+		// return nil, fmt.Errorf("credentials/configuration cannot be retrieved over an insecure connection")
+	}
+
+	queryVals := make(url.Values)
+	for _, k := range keys {
+		queryVals.Add(k, "")
+	}
+
+	// Execute GET on /minio/admin/v1/config-keys to get config of a setup.
+	resp, err := adm.executeMethod("GET",
+		requestData{
+			relPath:     "/v1/config-keys",
+			queryValues: queryVals,
+		})
+	defer closeResponse(resp)
+	if err != nil {
+		return nil, err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return nil, httpRespToErrorResponse(resp)
+	}
+
+	return DecryptServerConfigData(adm.secretAccessKey, resp.Body)
+}
+
 // SetConfig - set config supplied as config.json for the setup.
 func (adm *AdminClient) SetConfig(config io.Reader) (err error) {
 	const maxConfigJSONSize = 256 * 1024 // 256KiB
@@ -148,3 +180,35 @@ func (adm *AdminClient) SetConfig(config io.Reader) (err error) {
 
 	return nil
 }
+
+// SetConfigKeys - set config keys supplied as config.json for the setup.
+func (adm *AdminClient) SetConfigKeys(params map[string]string) error {
+	queryVals := make(url.Values)
+	for k, v := range params {
+		encryptedVal, err := EncryptServerConfigData(adm.secretAccessKey, []byte(v))
+		if err != nil {
+			return err
+		}
+		encodedVal := base64.StdEncoding.EncodeToString(encryptedVal)
+		queryVals.Add(k, string(encodedVal))
+	}
+
+	reqData := requestData{
+		relPath:     "/v1/config-keys",
+		queryValues: queryVals,
+	}
+
+	// Execute PUT on /minio/admin/v1/config-keys to set config.
+	resp, err := adm.executeMethod("PUT", reqData)
+
+	defer closeResponse(resp)
+	if err != nil {
+		return err
+	}
+
+	if resp.StatusCode != http.StatusOK {
+		return httpRespToErrorResponse(resp)
+	}
+
+	return nil
+}

pkg/madmin/examples/get-config-keys.go

@@ -0,0 +1,54 @@
+// +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 (
+	"bytes"
+	"encoding/json"
+	"log"
+
+	"github.com/minio/minio/pkg/madmin"
+)
+
+func main() {
+	// 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)
+	}
+
+	configBytes, err := madmClnt.GetConfigKeys([]string{"notify.amqp.1", "version"})
+	if err != nil {
+		log.Fatalf("failed due to: %v", err)
+	}
+
+	// Pretty-print config received as json.
+	var buf bytes.Buffer
+	err = json.Indent(&buf, configBytes, "", "\t")
+	if err != nil {
+		log.Fatalf("failed due to: %v", err)
+	}
+
+	log.Println("config received successfully: ", string(buf.Bytes()))
+}

pkg/madmin/examples/get-config.go

@@ -1,4 +1,6 @@
-/* +build ignore
+// +build ignore
+
+/*
  * Minio Cloud Storage, (C) 2017 Minio, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");

pkg/madmin/examples/set-config-keys.go

@@ -0,0 +1,53 @@
+// +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 (
+	"fmt"
+	"log"
+
+	"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)
+	}
+
+	err = madmClnt.SetConfigKeys(map[string]string{
+		"domain":           "example.com",
+		"notify.webhook.1": "{\"enable\": true, \"endpoint\": \"http://example.com/api/object-notifications\"}",
+	})
+
+	if err != nil {
+		log.Fatalln(err)
+	}
+
+	fmt.Println("Setting new configuration successfully executed.")
+}