Add etcd part of config support, add noColor/json support (#8439)

- Add color/json mode support for get/help commands
- Support ENV help for all sub-systems
- Add support for etcd as part of config

pkg/color/color.go

@@ -1,11 +1,25 @@
+/*
+ * MinIO Cloud Storage, (C) 2019 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 color
 
 import (
 	"fmt"
-	"os"
 
 	"github.com/fatih/color"
-	"github.com/mattn/go-isatty"
 )
 
 // global colors.
@@ -13,7 +27,7 @@ var (
 	// Check if we stderr, stdout are dumb terminals, we do not apply
 	// ansi coloring on dumb terminals.
 	IsTerminal = func() bool {
-		return isatty.IsTerminal(os.Stdout.Fd()) && isatty.IsTerminal(os.Stderr.Fd())
+		return !color.NoColor
 	}
 
 	Bold = func() func(a ...interface{}) string {
@@ -22,78 +36,91 @@ var (
 		}
 		return fmt.Sprint
 	}()
+
 	Red = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgRed).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	Blue = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgBlue).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	Yellow = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgYellow).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	Green = func() func(a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgGreen).SprintFunc()
 		}
 		return fmt.Sprint
 	}()
+
 	GreenBold = func() func(a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgGreen, color.Bold).SprintFunc()
 		}
 		return fmt.Sprint
 	}()
+
 	CyanBold = func() func(a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgCyan, color.Bold).SprintFunc()
 		}
 		return fmt.Sprint
 	}()
+
 	YellowBold = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgYellow, color.Bold).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	BlueBold = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgBlue, color.Bold).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	BgYellow = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.BgYellow).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	Black = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgBlack).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	FgRed = func() func(a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgRed).SprintFunc()
 		}
 		return fmt.Sprint
 	}()
+
 	BgRed = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.BgRed).SprintfFunc()
 		}
 		return fmt.Sprintf
 	}()
+
 	FgWhite = func() func(format string, a ...interface{}) string {
 		if IsTerminal() {
 			return color.New(color.FgWhite).SprintfFunc()