feat: Enable automatic stream sharding by default (#12451)

Signed-off-by: Edward Welch <edward.welch@grafana.com>

docs/sources/setup/upgrade/_index.md

@@ -174,6 +174,10 @@ This new metric will provide a more clear signal that there is an issue with ing
 | `legacy-read-mode`                                     | false       | true        | Deprecated. It will be removed in the next minor release. |
 {{% /responsive-table %}}
 
+#### Automatic stream sharding is enabled by default
+
+Automatic stream sharding helps keep the write load of high volume streams balanced across ingesters and helps to avoid hot-spotting. Check out the [operations page](https://grafana.com/docs/loki/latest/operations/automatic-stream-sharding/) for more information
+
 #### Write dedupe cache is deprecated
 Write dedupe cache is deprecated because it not required by the newer single store indexes ([TSDB]({{< relref "../../operations/storage/tsdb" >}}) and [boltdb-shipper]({{< relref "../../operations/storage/boltdb-shipper" >}})).
 If you using a [legacy index type]({{< relref "../../storage#index-storage" >}}), consider migrating to TSDB (recommended).

pkg/distributor/shardstreams/config.go

@@ -16,8 +16,8 @@ type Config struct {
 }
 
 func (cfg *Config) RegisterFlagsWithPrefix(prefix string, fs *flag.FlagSet) {
-	fs.BoolVar(&cfg.Enabled, prefix+".enabled", false, "Automatically shard streams to keep them under the per-stream rate limit")
+	fs.BoolVar(&cfg.Enabled, prefix+".enabled", true, "Automatically shard streams to keep them under the per-stream rate limit")
 	fs.BoolVar(&cfg.LoggingEnabled, prefix+".logging-enabled", false, "Enable logging when sharding streams")
-	cfg.DesiredRate.Set("3mb") //nolint:errcheck
-	fs.Var(&cfg.DesiredRate, prefix+".desired-rate", "threshold used to cut a new shard. Default (3MB) means if a rate is above 3MB, it will be sharded.")
+	cfg.DesiredRate.Set("1536KB") //nolint:errcheck
+	fs.Var(&cfg.DesiredRate, prefix+".desired-rate", "threshold used to cut a new shard. Default (1536KB) means if a rate is above 1536KB/s, it will be sharded.")
 }

pkg/ingester/instance_test.go

@@ -1082,8 +1082,8 @@ func TestStreamShardingUsage(t *testing.T) {
 	tenantShardStreamsCfg := limiter.limits.ShardStreams(customTenant1)
 
 	t.Run("test default configuration", func(t *testing.T) {
-		require.Equal(t, false, defaultShardStreamsCfg.Enabled)
-		require.Equal(t, "3MB", defaultShardStreamsCfg.DesiredRate.String())
+		require.Equal(t, true, defaultShardStreamsCfg.Enabled)
+		require.Equal(t, "1536KB", defaultShardStreamsCfg.DesiredRate.String())
 		require.Equal(t, false, defaultShardStreamsCfg.LoggingEnabled)
 	})