gateway: Use default params when no args provided (#4315)

For S3 & Azure, use default parameters when no arguments (endpoint) are
provided. This also avoids a crash.

cmd/gateway-azure.go

@@ -33,6 +33,7 @@ import (
 	"time"
 
 	"github.com/Azure/azure-sdk-for-go/storage"
+	"github.com/minio/cli"
 	"github.com/minio/minio-go/pkg/policy"
 	"github.com/minio/sha256-simd"
 )
@@ -156,14 +157,20 @@ func azureToObjectError(err error, params ...string) error {
 }
 
 // Inits azure blob storage client and returns AzureObjects.
-func newAzureLayer(args []string) (GatewayLayer, error) {
-	endPoint, secure, err := parseGatewayEndpoint(args[0])
-	if err != nil {
-		return nil, err
-	}
+func newAzureLayer(args cli.Args) (GatewayLayer, error) {
 
-	if endPoint == "" {
-		endPoint = storage.DefaultBaseURL
+	var err error
+
+	// Default endpoint parameters
+	endPoint := storage.DefaultBaseURL
+	secure := true
+
+	// If user provided some parameters
+	if len(args) > 0 {
+		endPoint, secure, err = parseGatewayEndpoint(args.First())
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	account := os.Getenv("MINIO_ACCESS_KEY")

cmd/gateway-gcs.go

@@ -17,32 +17,24 @@
 package cmd
 
 import (
+	"bytes"
 	"context"
 	"crypto/sha256"
+	"encoding/base64"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"hash"
 	"io"
+	"path"
 	"strconv"
 	"strings"
 
-	"encoding/hex"
-
 	"cloud.google.com/go/storage"
-
 	"google.golang.org/api/googleapi"
 	"google.golang.org/api/iterator"
 
-	"encoding/base64"
-
-	"bytes"
-
-	// this package contains the url code of go 1.8
-	// due to compatibility with older versions
-	// copied it to our rep
-
-	"path"
-
+	"github.com/minio/cli"
 	minio "github.com/minio/minio-go"
 	"github.com/minio/minio-go/pkg/policy"
 )
@@ -171,7 +163,7 @@ type gcsGateway struct {
 }
 
 // newGCSGateway returns gcs gatewaylayer
-func newGCSGateway(args []string) (GatewayLayer, error) {
+func newGCSGateway(args cli.Args) (GatewayLayer, error) {
 	if len(args) != 1 {
 		return nil, fmt.Errorf("ProjectID expected")
 	}
@@ -183,7 +175,7 @@ func newGCSGateway(args []string) (GatewayLayer, error) {
 	endpoint := "storage.googleapis.com"
 	secure := true
 
-	projectID := args[0]
+	projectID := args.First()
 
 	ctx := context.Background()
 

cmd/gateway-main.go

@@ -179,7 +179,7 @@ const (
 )
 
 // GatewayFn returns the GatewayLayer for the backend
-type GatewayFn func([]string) (GatewayLayer, error)
+type GatewayFn func(cli.Args) (GatewayLayer, error)
 
 var (
 	backends = map[gatewayBackend]GatewayFn{

cmd/gateway-s3.go

@@ -17,13 +17,15 @@
 package cmd
 
 import (
-	"encoding/hex"
 	"errors"
 	"io"
 	"net/http"
 	"os"
 	"path"
 
+	"encoding/hex"
+
+	"github.com/minio/cli"
 	minio "github.com/minio/minio-go"
 	"github.com/minio/minio-go/pkg/policy"
 )
@@ -99,15 +101,21 @@ type s3Objects struct {
 }
 
 // newS3Gateway returns s3 gatewaylayer
-func newS3Gateway(args []string) (GatewayLayer, error) {
-	endpoint, secure, err := parseGatewayEndpoint(args[0])
-	if err != nil {
-		return nil, err
-	}
+func newS3Gateway(args cli.Args) (GatewayLayer, error) {
 
-	if endpoint == "" {
-		endpoint = "s3.amazonaws.com"
-		secure = true
+	var err error
+
+	// Default endpoint parameters
+	endpoint := "s3.amazonaws.com"
+	secure := true
+
+	// Check if user provided some parameters
+	if len(args) > 0 {
+		// Override default params if the endpoint is provided
+		endpoint, secure, err = parseGatewayEndpoint(args.First())
+		if err != nil {
+			return nil, err
+		}
 	}
 
 	accessKey := os.Getenv("MINIO_ACCESS_KEY")