Add flag to disable tracing activation

cmd/loki/main.go

@@ -58,19 +58,21 @@ func main() {
 		os.Exit(1)
 	}
 
-	// Setting the environment variable JAEGER_AGENT_HOST enables tracing
-	trace, err := tracing.NewFromEnv(fmt.Sprintf("loki-%s", config.Target))
-	if err != nil {
-		level.Error(util.Logger).Log("msg", "error in initializing tracing. tracing will not be enabled", "err", err)
-	}
-	defer func() {
-		if trace != nil {
-			if err := trace.Close(); err != nil {
-				level.Error(util.Logger).Log("msg", "error closing tracing", "err", err)
-			}
+	if config.Tracing.Enabled {
+		// Setting the environment variable JAEGER_AGENT_HOST enables tracing
+		trace, err := tracing.NewFromEnv(fmt.Sprintf("loki-%s", config.Target))
+		if err != nil {
+			level.Error(util.Logger).Log("msg", "error in initializing tracing. tracing will not be enabled", "err", err)
 		}
+		defer func() {
+			if trace != nil {
+				if err := trace.Close(); err != nil {
+					level.Error(util.Logger).Log("msg", "error closing tracing", "err", err)
+				}
+			}
 
-	}()
+		}()
+	}
 
 	// Start Loki
 	t, err := loki.New(config)

docs/configuration/README.md

@@ -25,8 +25,10 @@ Configuration examples can be found in the [Configuration Examples](examples.md)
 * [table_manager_config](#table_manager_config)
   * [provision_config](#provision_config)
     * [auto_scaling_config](#auto_scaling_config)
+* [tracing_config](#tracing_config)
 * [Runtime Configuration file](#runtime-configuration-file)
 
+
 ## Configuration File Reference
 
 To specify which configuration file to load, pass the `-config.file` flag at the
@@ -97,6 +99,9 @@ Supported contents and default values of `loki.yaml`:
 
 # Configuration for "runtime config" module, responsible for reloading runtime configuration file.
 [runtime_config: <runtime_config>]
+
+#Configuration for tracing
+[tracing: <tracing_config>]
 ```
 
 ## server_config
@@ -1044,6 +1049,15 @@ The `auto_scaling_config` block configures autoscaling for DynamoDB.
 [target: <float> | default = 80]
 ```
 
+## tracing_config
+
+The `tracing_config` block configures tracing for Jaeger. Currently limited to disable auto-configuration per [environment variables](https://www.jaegertracing.io/docs/1.16/client-features/) only.
+
+```yaml
+# Whether or not tracing should be enabled.
+[enabled: <boolean>: default = true]
+```
+
 ## Runtime Configuration file
 
 Loki has a concept of "runtime config" file, which is simply a file that is reloaded while Loki is running. It is used by some Loki components to allow operator to change some aspects of Loki configuration without restarting it. File is specified by using `-runtime-config.file=<filename>` flag and reload period (which defaults to 10 seconds) can be changed by `-runtime-config.reload-period=<duration>` flag. Previously this mechanism was only used by limits overrides, and flags were called `-limits.per-user-override-config=<filename>` and `-limits.per-user-override-period=10s` respectively. These are still used, if `-runtime-config.file=<filename>` is not specified.

pkg/loki/loki.go

@@ -32,6 +32,7 @@ import (
 	"github.com/grafana/loki/pkg/querier"
 	"github.com/grafana/loki/pkg/querier/queryrange"
 	"github.com/grafana/loki/pkg/storage"
+	"github.com/grafana/loki/pkg/tracing"
 	serverutil "github.com/grafana/loki/pkg/util/server"
 	"github.com/grafana/loki/pkg/util/validation"
 )
@@ -57,6 +58,7 @@ type Config struct {
 	QueryRange       queryrange.Config           `yaml:"query_range,omitempty"`
 	RuntimeConfig    runtimeconfig.ManagerConfig `yaml:"runtime_config,omitempty"`
 	MemberlistKV     memberlist.KVConfig         `yaml:"memberlist"`
+	Tracing          tracing.Config              `yaml:"tracing"`
 }
 
 // RegisterFlags registers flag.
@@ -81,6 +83,7 @@ func (c *Config) RegisterFlags(f *flag.FlagSet) {
 	c.Worker.RegisterFlags(f)
 	c.QueryRange.RegisterFlags(f)
 	c.RuntimeConfig.RegisterFlags(f)
+	c.Tracing.RegisterFlags(f)
 }
 
 // Validate the config and returns an error if the validation

pkg/tracing/config.go

@@ -0,0 +1,13 @@
+package tracing
+
+import (
+	"flag"
+)
+
+type Config struct {
+	Enabled bool `yaml:"enabled"`
+}
+
+func (cfg *Config) RegisterFlags(f *flag.FlagSet) {
+	f.BoolVar(&cfg.Enabled, "tracing.enabled", true, "Set to false to disable tracing.")
+}