Refactor storage class parsing for Gateway mode (#5331)

This PR updates the behaviour to print relevant error message
if storage class is set in config.json for gateway

This PR also fixes the case where storage class set via
environment variables is not parsed properly into config.json.

cmd/config-current.go

@@ -20,7 +20,6 @@ import (
 	"errors"
 	"fmt"
 	"io/ioutil"
-	"strconv"
 	"sync"
 
 	"github.com/minio/minio/pkg/auth"
@@ -108,46 +107,35 @@ func (s *serverConfig) SetStorageClass(standardClass, rrsClass storageClass) {
 	s.Lock()
 	defer s.Unlock()
 
-	// Set the values
-	s.StorageClass.Standard = standardClass.Scheme + strconv.Itoa(standardClass.Parity)
-	s.StorageClass.RRS = rrsClass.Scheme + strconv.Itoa(rrsClass.Parity)
+	s.StorageClass.Standard = standardClass
+	s.StorageClass.RRS = rrsClass
 }
 
 // GetStorageClass reads storage class fields from current config, parses and validates it.
 // It returns the standard and reduced redundancy storage class struct
-func (s *serverConfig) GetStorageClass() (ssc, rrsc storageClass) {
+func (s *serverConfig) GetStorageClass() (storageClass, storageClass) {
 	s.RLock()
 	defer s.RUnlock()
 
 	var err error
+	// Storage Class from config.json is already parsed and stored in s.StorageClass
+	// Now validate the storage class fields
+	ssc := s.StorageClass.Standard
+	rrsc := s.StorageClass.RRS
 
-	if s.StorageClass.Standard != "" {
-		// Parse the values read from config file into storageClass struct
-		ssc, err = parseStorageClass(s.StorageClass.Standard)
-		fatalIf(err, "Invalid value %s set in config.json", s.StorageClass.Standard)
-	}
-
-	if s.StorageClass.RRS != "" {
-		// Parse the values read from config file into storageClass struct
-		rrsc, err = parseStorageClass(s.StorageClass.RRS)
-		fatalIf(err, "Invalid value %s set in config.json", s.StorageClass.RRS)
-	}
-
-	// Validation is done after parsing both the storage classes. This is needed because we need one
-	// storage class value to deduce the correct value of the other storage class.
 	if rrsc.Scheme != "" {
 		err = validateRRSParity(rrsc.Parity, ssc.Parity)
-		fatalIf(err, "Invalid value %s set in config.json", s.StorageClass.RRS)
+		fatalIf(err, "Invalid value %s:%d set in config.json", rrsc.Scheme, rrsc.Parity)
 		globalIsStorageClass = true
 	}
 
 	if ssc.Scheme != "" {
 		err = validateSSParity(ssc.Parity, rrsc.Parity)
-		fatalIf(err, "Invalid value %s set in config.json", s.StorageClass.Standard)
+		fatalIf(err, "Invalid value %s:%d set in config.json", ssc.Scheme, ssc.Parity)
 		globalIsStorageClass = true
 	}
 
-	return
+	return s.StorageClass.Standard, s.StorageClass.RRS
 }
 
 // GetCredentials get current credentials.
@@ -169,11 +157,12 @@ func (s *serverConfig) Save() error {
 
 func newServerConfig() *serverConfig {
 	srvCfg := &serverConfig{
-		Version:    serverConfigVersion,
-		Credential: auth.MustGetNewCredentials(),
-		Region:     globalMinioDefaultRegion,
-		Browser:    true,
-		Notify:     &notifier{},
+		Version:      serverConfigVersion,
+		Credential:   auth.MustGetNewCredentials(),
+		Region:       globalMinioDefaultRegion,
+		Browser:      true,
+		StorageClass: storageClassConfig{},
+		Notify:       &notifier{},
 	}
 
 	// Make sure to initialize notification configs.