Fix object prefix not being stripped for Dell ECS (#561)

* Fix object prefix not being stripped for Dell ECS

This commit ensure that the same object prefix string is used to query and strip
an object when listing all the objects in a bucket.

Some S3 implementations (in this case Dell ECS) cannot be relied upon to return
the correct `res.Prefix`. Dell ECS will return it URLencoded, e.g. "traceID%2F"
instead of "traceID/".

* Add changelog

* Update CHANGELOG.md

Co-authored-by: Graham Reed <greed@7deadly.org>

Co-authored-by: Graham Reed <greed@7deadly.org>

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 * [ENHANCEMENT] Add a Shutdown handler to flush data to backend, at "/shutdown". [#526](https://github.com/grafana/tempo/pull/526)
 * [BUGFIX] Fixes permissions errors on startup in GCS. [#554](https://github.com/grafana/tempo/pull/554)
+* [BUGFIX] Fixes error where Dell ECS cannot list objects. [#561](https://github.com/grafana/tempo/pull/561)
+
 
 ## v0.6.0
 

tempodb/backend/s3/s3.go

@@ -271,16 +271,17 @@ func (rw *readerWriter) Tenants(ctx context.Context) ([]string, error) {
 
 // Blocks implements backend.Reader
 func (rw *readerWriter) Blocks(ctx context.Context, tenantID string) ([]uuid.UUID, error) {
+	prefix := tenantID + "/"
 	// ListObjects(bucket, prefix, marker, delimiter string, maxKeys int)
-	res, err := rw.core.ListObjects(rw.cfg.Bucket, tenantID+"/", "", "/", 0)
+	res, err := rw.core.ListObjects(rw.cfg.Bucket, prefix, "", "/", 0)
 	if err != nil {
 		return nil, errors.Wrapf(err, "error listing blocks in s3 bucket, bucket: %s", rw.cfg.Bucket)
 	}
 
 	level.Debug(rw.logger).Log("msg", "listing blocks", "tenantID", tenantID, "found", len(res.CommonPrefixes))
 	var blockIDs []uuid.UUID
 	for _, cp := range res.CommonPrefixes {
-		blockID, err := uuid.Parse(strings.Split(strings.TrimPrefix(cp.Prefix, res.Prefix), "/")[0])
+		blockID, err := uuid.Parse(strings.Split(strings.TrimPrefix(cp.Prefix, prefix), "/")[0])
 		if err != nil {
 			return nil, errors.Wrapf(err, "error parsing uuid of obj, objectName: %s", cp.Prefix)
 		}