Bring nicer ui error if creds are missing in Gateway (#6003)

cmd/gateway-main.go

@@ -18,7 +18,6 @@ package cmd
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"net/url"
 	"os"
@@ -151,10 +150,7 @@ func StartGateway(ctx *cli.Context, gw Gateway) {
 
 	// Validate if we have access, secret set through environment.
 	if !globalIsEnvCreds {
-		reqInfo := (&logger.ReqInfo{}).AppendTags("gatewayName", gatewayName)
-		contxt := logger.SetReqInfo(context.Background(), reqInfo)
-		logger.LogIf(contxt, errors.New("Access and Secret keys should be set through ENVs for backend"))
-		cli.ShowCommandHelpAndExit(ctx, gatewayName, 1)
+		logger.Fatal(uiErrEnvCredentialsMissing(nil), "Unable to start gateway")
 	}
 
 	// Create certs path.

cmd/gateway/nas/gateway-nas.go

@@ -85,17 +85,16 @@ EXAMPLES:
 // Handler for 'minio gateway nas' command line.
 func nasGatewayMain(ctx *cli.Context) {
 	// Validate gateway arguments.
-	host := ctx.Args().First()
-	if host == "help" {
+	if !ctx.Args().Present() || ctx.Args().First() == "help" {
 		cli.ShowCommandHelpAndExit(ctx, nasBackend, 1)
 	}
-	// Validate gateway arguments.
-	minio.StartGateway(ctx, &NAS{host})
+
+	minio.StartGateway(ctx, &NAS{ctx.Args().First()})
 }
 
 // NAS implements Gateway.
 type NAS struct {
-	host string
+	path string
 }
 
 // Name implements Gateway interface.
@@ -106,7 +105,7 @@ func (g *NAS) Name() string {
 // NewGatewayLayer returns nas gatewaylayer.
 func (g *NAS) NewGatewayLayer(creds auth.Credentials) (minio.ObjectLayer, error) {
 	var err error
-	newObject, err := minio.NewFSObjectLayer(g.host)
+	newObject, err := minio.NewFSObjectLayer(g.path)
 	if err != nil {
 		return nil, err
 	}

cmd/ui-errors.go

@@ -54,6 +54,12 @@ var (
 Secret key should be in between 8 and 40 characters.`,
 	)
 
+	uiErrEnvCredentialsMissing = newUIErrFn(
+		"Credentials missing",
+		"Please provide correct credentials",
+		`Access key and Secret key should be specified in Gateway mode from environment variables MINIO_ACCESS_KEY and MINIO_SECRET_KEY respectively.`,
+	)
+
 	uiErrInvalidErasureEndpoints = newUIErrFn(
 		"Invalid endpoint(s) in erasure mode",
 		"Please provide correct combination of local/remote paths",