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/madmin/config-help-commands.go

@@ -18,16 +18,50 @@
 package madmin
 
 import (
+	"encoding/json"
 	"io"
 	"net/http"
 	"net/url"
+	"strings"
+	"text/tabwriter"
+	"text/template"
+
+	"github.com/minio/minio/pkg/color"
 )
 
+// Help template used by all sub-systems
+const Help = `{{colorBlueBold "Key"}}{{"\t"}}{{colorBlueBold "Description"}}
+{{colorYellowBold "----"}}{{"\t"}}{{colorYellowBold "----"}}
+{{range $key, $value := .}}{{colorCyanBold $key}}{{ "\t" }}{{$value}}
+{{end}}`
+
+// HelpEnv template used by all sub-systems
+const HelpEnv = `{{colorBlueBold "KeyEnv"}}{{"\t"}}{{colorBlueBold "Description"}}
+{{colorYellowBold "----"}}{{"\t"}}{{colorYellowBold "----"}}
+{{range $key, $value := .}}{{colorCyanBold $key}}{{ "\t" }}{{$value}}
+{{end}}`
+
+var funcMap = template.FuncMap{
+	"colorBlueBold":   color.BlueBold,
+	"colorYellowBold": color.YellowBold,
+	"colorCyanBold":   color.CyanBold,
+}
+
+// HelpTemplate - captures config help template
+var HelpTemplate = template.Must(template.New("config-help").Funcs(funcMap).Parse(Help))
+
+// HelpEnvTemplate - captures config help template
+var HelpEnvTemplate = template.Must(template.New("config-help-env").Funcs(funcMap).Parse(HelpEnv))
+
 // HelpConfigKV - return help for a given sub-system.
-func (adm *AdminClient) HelpConfigKV(subSys, key string) (io.ReadCloser, error) {
+func (adm *AdminClient) HelpConfigKV(subSys, key string, envOnly bool) (io.Reader, error) {
 	v := url.Values{}
 	v.Set("subSys", subSys)
 	v.Set("key", key)
+	if envOnly {
+		v.Set("env", "")
+	}
+
 	reqData := requestData{
 		relPath:     adminAPIPrefix + "/help-config-kv",
 		queryValues: v,
@@ -38,12 +72,29 @@ func (adm *AdminClient) HelpConfigKV(subSys, key string) (io.ReadCloser, error)
 	if err != nil {
 		return nil, err
 	}
+	defer closeResponse(resp)
 
 	if resp.StatusCode != http.StatusOK {
-		defer closeResponse(resp)
 		return nil, httpRespToErrorResponse(resp)
 	}
 
-	return resp.Body, nil
+	var help = make(map[string]string)
+	d := json.NewDecoder(resp.Body)
+	if err = d.Decode(&help); err != nil {
+		return nil, err
+	}
 
+	var s strings.Builder
+	w := tabwriter.NewWriter(&s, 1, 8, 2, ' ', 0)
+	if !envOnly {
+		err = HelpTemplate.Execute(w, help)
+	} else {
+		err = HelpEnvTemplate.Execute(w, help)
+	}
+	if err != nil {
+		return nil, err
+	}
+
+	w.Flush()
+	return strings.NewReader(s.String()), nil
 }