Set span.kind to client in query-frontend (grafana#975)

* Set span.kind to client in query-frontend

* I was too slow

* Use opentracing

* Fix changelog

CHANGELOG.md

@@ -55,6 +55,7 @@
 * [BUGFIX] Fix "magic number" errors and other block mishandling when an ingester forcefully shuts down [#937](https://github.com/grafana/tempo/issues/937) (@mdisibio)
 * [BUGFIX] Fix compactor memory leak [#806](https://github.com/grafana/tempo/pull/806) (@mdisibio)
 * [BUGFIX] Fix an issue with WAL replay of zero-length search data when search is disabled. [#968](https://github.com/grafana/tempo/pull/968) (@annanay25)
+* [BUGFIX] Set span's tag `span.kind` to `client` in query-frontend [#975](https://github.com/grafana/tempo/pull/975) (@mapno)
 
 ## v1.1.0 / 2021-08-26
 * [CHANGE] Upgrade Cortex from v1.9.0 to v1.9.0-131-ga4bf10354 [#841](https://github.com/grafana/tempo/pull/841) (@aknuds1)

modules/frontend/retry.go

@@ -5,6 +5,7 @@ import (
 	"net/http"
 
 	"github.com/opentracing/opentracing-go"
+	"github.com/opentracing/opentracing-go/ext"
 	ot_log "github.com/opentracing/opentracing-go/log"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
@@ -37,6 +38,7 @@ func (r retryWare) Do(req *http.Request) (*http.Response, error) {
 	ctx := req.Context()
 	span, ctx := opentracing.StartSpanFromContext(ctx, "frontend.Retry")
 	defer span.Finish()
+	ext.SpanKindRPCClient.Set(span)
 
 	// context propagation
 	req = req.WithContext(ctx)