From bcf784375b77aa61377eb6a4a872957053e21a1a Mon Sep 17 00:00:00 2001
From: bergquist <carl.bergquist@gmail.com>
Date: Mon, 18 Sep 2017 11:03:17 +0200
Subject: [PATCH] make it possible to configure sampler type

---
 conf/defaults.ini      |  2 ++
 conf/sample.ini        |  2 ++
 pkg/tracing/tracing.go | 14 +++++++++-----
 3 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/conf/defaults.ini b/conf/defaults.ini
index 5eb3c358f44..5abd27e5c51 100644
--- a/conf/defaults.ini
+++ b/conf/defaults.ini
@@ -458,6 +458,8 @@ url = https://grafana.com
 address =
 # tag that will always be included in when creating new spans. ex (tag1:value1,tag2:value2)
 always_included_tag =
+# Type specifies the type of the sampler: const, probabilistic, rateLimiting, or remote
+sampler_type = const
 # jaeger samplerconfig param
 # for "const" sampler, 0 or 1 for always false/true respectively
 # for "probabilistic" sampler, a probability between 0 and 1
diff --git a/conf/sample.ini b/conf/sample.ini
index e8394631a5c..076b9306d84 100644
--- a/conf/sample.ini
+++ b/conf/sample.ini
@@ -397,6 +397,8 @@
 ;address = localhost:6831
 # Tag that will always be included in when creating new spans. ex (tag1:value1,tag2:value2)
 ;always_included_tag = tag1:value1
+# Type specifies the type of the sampler: const, probabilistic, rateLimiting, or remote
+;sampler_type = const
 # jaeger samplerconfig param
 # for "const" sampler, 0 or 1 for always false/true respectively
 # for "probabilistic" sampler, a probability between 0 and 1
diff --git a/pkg/tracing/tracing.go b/pkg/tracing/tracing.go
index 010f5053b60..be81cd7e794 100644
--- a/pkg/tracing/tracing.go
+++ b/pkg/tracing/tracing.go
@@ -2,14 +2,12 @@ package tracing
 
 import (
 	"io"
-	"io/ioutil"
 	"strings"
 
 	"github.com/grafana/grafana/pkg/log"
 	"github.com/grafana/grafana/pkg/setting"
 
 	opentracing "github.com/opentracing/opentracing-go"
-	jaeger "github.com/uber/jaeger-client-go"
 	jaegercfg "github.com/uber/jaeger-client-go/config"
 	ini "gopkg.in/ini.v1"
 )
@@ -22,6 +20,7 @@ type TracingSettings struct {
 	Enabled      bool
 	Address      string
 	CustomTags   map[string]string
+	SamplerType  string
 	SamplerParam float64
 }
 
@@ -44,6 +43,7 @@ func parseSettings(file *ini.File) *TracingSettings {
 	}
 
 	settings.CustomTags = splitTagSettings(section.Key("always_included_tag").MustString(""))
+	settings.SamplerType = section.Key("sampler_type").MustString("")
 	settings.SamplerParam = section.Key("sampler_param").MustFloat64(1)
 
 	return settings
@@ -51,13 +51,13 @@ func parseSettings(file *ini.File) *TracingSettings {
 
 func internalInit(settings *TracingSettings) (io.Closer, error) {
 	if !settings.Enabled {
-		return ioutil.NopCloser(nil), nil
+		return &nullCloser{}, nil
 	}
 
 	cfg := jaegercfg.Configuration{
 		Disabled: !settings.Enabled,
-		Sampler: &jaegercfg.SamplerConfig{ //we currently only support SamplerConfig. Open an issue if you need another.
-			Type:  jaeger.SamplerTypeConst,
+		Sampler: &jaegercfg.SamplerConfig{
+			Type:  settings.SamplerType,
 			Param: settings.SamplerParam,
 		},
 		Reporter: &jaegercfg.ReporterConfig{
@@ -110,3 +110,7 @@ func (jlw *jaegerLogWrapper) Error(msg string) {
 func (jlw *jaegerLogWrapper) Infof(msg string, args ...interface{}) {
 	jlw.logger.Info(msg, args)
 }
+
+type nullCloser struct{}
+
+func (*nullCloser) Close() error { return nil }