Fix minimum replication workers started (#10560)

This PR also fixes GetReplicationConfiguration permission
in web-handlers.go to use bucket as resource

cmd/bucket-replication.go

@@ -304,6 +304,11 @@ var (
 )
 
 func newReplicationState() *replicationState {
+
+	// fix minimum concurrent replication to 1 for single CPU setup
+	if globalReplicationConcurrent == 0 {
+		globalReplicationConcurrent = 1
+	}
 	rs := &replicationState{
 		replicaCh: make(chan ObjectInfo, globalReplicationConcurrent*2),
 	}

cmd/web-handlers.go

@@ -1025,7 +1025,7 @@ func (web *webAPIHandlers) Upload(w http.ResponseWriter, r *http.Request) {
 			BucketName:      bucket,
 			ConditionValues: getConditionValues(r, "", claims.AccessKey, claims.Map()),
 			IsOwner:         owner,
-			ObjectName:      object,
+			ObjectName:      "",
 			Claims:          claims.Map(),
 		}) {
 			replPerms = ErrNone

docs/bucket/replication/README.md

@@ -129,6 +129,8 @@ Replication status can be seen in the metadata on the source and destination obj
 
 To perform bi-directional replication, repeat the above process on the target site - this time setting the source bucket as the replication target.
 
+It is recommended that replication be run in a system with atleast two CPU's available to the process, so that replication can run in its own thread.
+
 ![put](https://raw.githubusercontent.com/minio/minio/master/docs/bucket/replication/PUT_bucket_replication.png)
 
 ![head](https://raw.githubusercontent.com/minio/minio/master/docs/bucket/replication/HEAD_bucket_replication.png)