Add tracer plugin

define an interface for creating and configuring tracers
add the Jaeger tracer as a plugin

License: MIT
Signed-off-by: ForrestWeston <forrest@protocol.ai>

plugin/loader/initializer.go

@@ -20,9 +20,20 @@ func initialize(plugins []plugin.Plugin) error {
 
 func run(plugins []plugin.Plugin) error {
 	for _, pl := range plugins {
-		err := runIPLDPlugin(pl)
-		if err != nil {
-			return err
+		switch pl.(type) {
+		case plugin.PluginIPLD:
+			err := runIPLDPlugin(pl)
+			if err != nil {
+				return err
+			}
+		case plugin.PluginTracer:
+			err := runTracerPlugin(pl)
+			if err != nil {
+				return err
+			}
+		default:
+			//since this is a developer error if we hit this case
+			panic(pl)
 		}
 	}
 	return nil
@@ -41,3 +52,15 @@ func runIPLDPlugin(pl plugin.Plugin) error {
 
 	return ipldpl.RegisterInputEncParsers(coredag.DefaultInputEncParsers)
 }
+
+func runTracerPlugin(pl plugin.Plugin) error {
+	tracerpl, ok := pl.(plugin.PluginTracer)
+	if !ok {
+		return nil
+	}
+	err := tracerpl.InitGlobalTracer(nil)
+	if err != nil {
+		return err
+	}
+	return nil
+}

plugin/loader/preload_list

@@ -4,3 +4,4 @@
 # name             go-path                  number of the sub-plugin
 
 #ipldgit github.com/ipfs/go-ipfs/plugin/plugins/git 0
+#jaegertracer github.com/ipfs/go-ipfs/plugin/plugins/jaeger 0

plugin/plugins/jaeger/jaeger.go

@@ -0,0 +1,50 @@
+package jaeger
+
+import (
+	"github.com/ipfs/go-ipfs/plugin"
+	opentrace "github.com/opentracing/opentracing-go"
+	config "github.com/uber/jaeger-client-go/config"
+)
+
+// Plugins is exported list of plugins that will be loaded
+var Plugins = []plugin.Plugin{
+	&jaegerPlugin{},
+}
+
+type jaegerPlugin struct{}
+
+var _ plugin.PluginTracer = (*jaegerPlugin)(nil)
+
+func (*jaegerPlugin) Name() string {
+	return "jaeger"
+}
+
+func (*jaegerPlugin) Version() string {
+	return "0.0.1"
+}
+
+func (*jaegerPlugin) Init() error {
+	return nil
+}
+
+//Initalize a Jaeger tracer and set it as the global tracer in opentracing api
+func (*jaegerPlugin) InitGlobalTracer(cfg map[string]interface{}) error {
+	tracerCfg := &config.Configuration{
+		Sampler: &config.SamplerConfig{
+			Type:  "const",
+			Param: 1,
+		},
+		Reporter: &config.ReporterConfig{
+			LogSpans: false,
+		},
+	}
+	//service should be the ipfs node id
+	//we are ignoring the closer for now
+	tracer, _, err := tracerCfg.New("IPFS-NODE-ID")
+	if err != nil {
+		//probably failed to init the tracer
+		return err
+	}
+	opentrace.SetGlobalTracer(tracer)
+	return nil
+}

plugin/tracer.go

@@ -0,0 +1,7 @@
+package plugin
+
+// PluginTracer is an interface that can be implemented to add a tracer
+type PluginTracer interface {
+	Plugin
+	InitGlobalTracer(cfg map[string]interface{}) error
+}