fix: change SetRemoteTarget API to allow editing remote target granularly (#12175)

Currently, only credentials could be updated with
`mc admin bucket remote edit`. 

Allow updating synchronous replication flag, path, 
bandwidth and healthcheck duration on buckets, and
a flag to disable proxying in active-active replication.

pkg/madmin/remote-target-commands_test.go

@@ -0,0 +1,93 @@
+// Copyright (c) 2021 MinIO, Inc.
+//
+// This file is part of MinIO Object Storage stack
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package madmin
+
+import (
+	"net/url"
+	"testing"
+)
+
+func isOpsEqual(op1 []TargetUpdateType, op2 []TargetUpdateType) bool {
+	if len(op1) != len(op2) {
+		return false
+	}
+	for _, o1 := range op1 {
+		found := false
+		for _, o2 := range op2 {
+			if o2 == o1 {
+				found = true
+				break
+			}
+		}
+		if !found {
+			return false
+		}
+	}
+	return true
+}
+
+// TestGetTargetUpdateOps tests GetTargetUpdateOps
+func TestGetTargetUpdateOps(t *testing.T) {
+	testCases := []struct {
+		values      url.Values
+		expectedOps []TargetUpdateType
+	}{
+		{values: url.Values{
+			"update": []string{"true"}},
+			expectedOps: []TargetUpdateType{},
+		},
+		{values: url.Values{
+			"update": []string{"false"},
+			"path":   []string{"true"},
+		},
+			expectedOps: []TargetUpdateType{},
+		},
+		{values: url.Values{
+			"update": []string{"true"},
+			"path":   []string{""},
+		},
+			expectedOps: []TargetUpdateType{},
+		},
+		{values: url.Values{
+			"update": []string{"true"},
+			"path":   []string{"true"},
+			"bzzzz":  []string{"true"},
+		},
+			expectedOps: []TargetUpdateType{PathUpdateType},
+		},
+
+		{values: url.Values{
+			"update":      []string{"true"},
+			"path":        []string{"true"},
+			"creds":       []string{"true"},
+			"sync":        []string{"true"},
+			"proxy":       []string{"true"},
+			"bandwidth":   []string{"true"},
+			"healthcheck": []string{"true"},
+		},
+			expectedOps: []TargetUpdateType{
+				PathUpdateType, CredentialsUpdateType, SyncUpdateType, ProxyUpdateType, BandwidthLimitUpdateType, HealthCheckDurationUpdateType},
+		},
+	}
+	for i, test := range testCases {
+		gotOps := GetTargetUpdateOps(test.values)
+		if !isOpsEqual(gotOps, test.expectedOps) {
+			t.Fatalf("test %d: expected %v got %v", i+1, test.expectedOps, gotOps)
+		}
+	}
+}