Serve config at HTTP endpoint

CHANGELOG.md

@@ -9,12 +9,13 @@
 * [CHANGE] Rename IngestionMaxBatchSize to IngestionBurstSize. This is a **breaking change**. [#445](https://github.com/grafana/tempo/pull/445)
 * [ENHANCEMENT] Add docker-compose example for GCS along with new backend options [#397](https://github.com/grafana/tempo/pull/397)
 * [ENHANCEMENT] tempo-cli list blocks usability improvements [#403](https://github.com/grafana/tempo/pull/403)
-* [ENHANCEMENT] Add Query Frontend module to allow scaling the query path [#400](https://github.com/grafana/tempo/pull/400)
+* [ENHANCEMENT] Serve config at the "/config" endpoint. [#446](https://github.com/grafana/tempo/pull/446)
 * [BUGFIX] Compactor without GCS permissions fail silently [#379](https://github.com/grafana/tempo/issues/379)
 * [BUGFIX] Prevent race conditions between querier polling and ingesters clearing complete blocks [#421](https://github.com/grafana/tempo/issues/421)
 * [BUGFIX] Exclude blocks in last active window from compaction [#411](https://github.com/grafana/tempo/pull/411)
 * [BUGFIX] Mixin: Ignore metrics and query-frontend route when checking for TempoRequestLatency alert. [#440](https://github.com/grafana/tempo/pull/440)
 * [FEATURE] Add support for Azure Blob Storage backend [#340](https://github.com/grafana/tempo/issues/340)
+* [FEATURE] Add Query Frontend module to allow scaling the query path [#400](https://github.com/grafana/tempo/pull/400)
 
 ## v0.4.0
 

cmd/tempo/app/app.go

@@ -16,6 +16,7 @@ import (
 	"github.com/cortexproject/cortex/pkg/util/modules"
 	"github.com/cortexproject/cortex/pkg/util/services"
 	"github.com/go-kit/kit/log/level"
+	"gopkg.in/yaml.v3"
 
 	"github.com/weaveworks/common/middleware"
 	"github.com/weaveworks/common/server"
@@ -203,6 +204,7 @@ func (t *App) Run() error {
 	}
 
 	// before starting servers, register /ready handler and gRPC health check service.
+	t.server.HTTP.Path("/config").Handler(t.configHandler())
 	t.server.HTTP.Path("/ready").Handler(t.readyHandler(sm))
 	grpc_health_v1.RegisterHealthServer(t.server.GRPC, healthcheck.New(sm))
 
@@ -246,6 +248,23 @@ func (t *App) Run() error {
 	return sm.AwaitStopped(context.Background())
 }
 
+func (t *App) configHandler() http.HandlerFunc {
+	return func(w http.ResponseWriter, r *http.Request) {
+		out, err := yaml.Marshal(t.cfg)
+		if err != nil {
+			http.Error(w, err.Error(), http.StatusInternalServerError)
+			return
+		}
+
+		w.Header().Set("Content-Type", "text/yaml")
+		w.WriteHeader(http.StatusOK)
+		if _, err := w.Write(out); err != nil {
+			level.Error(util.Logger).Log("msg", "error writing response", "err", err)
+		}
+	}
+
+}
+
 func (t *App) readyHandler(sm *services.Manager) http.HandlerFunc {
 	return func(w http.ResponseWriter, r *http.Request) {
 		if !sm.IsHealthy() {

go.mod

@@ -50,6 +50,7 @@ require (
 	google.golang.org/genproto v0.0.0-20201028140639-c77dae4b0522 // indirect
 	google.golang.org/grpc v1.33.1
 	gopkg.in/yaml.v2 v2.3.0
+	gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776
 )
 
 // All of the below replace directives exist due to

vendor/modules.txt

@@ -1630,6 +1630,7 @@ gopkg.in/ini.v1
 ## explicit
 gopkg.in/yaml.v2
 # gopkg.in/yaml.v3 v3.0.0-20200615113413-eeeca48fe776
+## explicit
 gopkg.in/yaml.v3
 # honnef.co/go/tools v0.0.1-2020.1.4
 honnef.co/go/tools/arg