config: Add browser parameter (#3807)

browser new parameter receives "on" or "off" parameter which is similar
to MINIO_BROWSER

cmd/utils.go

@@ -23,11 +23,13 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"os"
 	"strings"
 
 	"encoding/json"
 
 	humanize "github.com/dustin/go-humanize"
+	"github.com/minio/mc/pkg/console"
 	"github.com/pkg/profile"
 )
 
@@ -238,3 +240,25 @@ func dumpRequest(r *http.Request) string {
 	}
 	return string(jsonBytes)
 }
+
+// Variant of getBrowserFromEnv but upon error fails right here.
+func mustGetBrowserFromEnv() string {
+	browser, err := getBrowserFromEnv()
+	if err != nil {
+		console.Fatalf("Unable to load MINIO_BROWSER value from environment. Err: %s.\n", err)
+	}
+	return browser
+}
+
+//
+func getBrowserFromEnv() (string, error) {
+	b := os.Getenv("MINIO_BROWSER")
+	if strings.TrimSpace(b) == "" {
+		return "", nil
+	}
+	if !strings.EqualFold(b, "off") && !strings.EqualFold(b, "on") {
+		return "", errInvalidArgument
+	}
+	globalIsEnvBrowser = true
+	return strings.ToLower(b), nil
+}