Elastic APM tracer implementation

pkg/config/static/static_config.go

@@ -19,6 +19,7 @@ import (
 	"github.com/containous/traefik/v2/pkg/provider/rest"
 	"github.com/containous/traefik/v2/pkg/tls"
 	"github.com/containous/traefik/v2/pkg/tracing/datadog"
+	"github.com/containous/traefik/v2/pkg/tracing/elastic"
 	"github.com/containous/traefik/v2/pkg/tracing/haystack"
 	"github.com/containous/traefik/v2/pkg/tracing/instana"
 	"github.com/containous/traefik/v2/pkg/tracing/jaeger"
@@ -144,6 +145,7 @@ type Tracing struct {
 	Datadog       *datadog.Config  `description:"Settings for Datadog." json:"datadog,omitempty" toml:"datadog,omitempty" yaml:"datadog,omitempty" export:"true" label:"allowEmpty"`
 	Instana       *instana.Config  `description:"Settings for Instana." json:"instana,omitempty" toml:"instana,omitempty" yaml:"instana,omitempty" export:"true" label:"allowEmpty"`
 	Haystack      *haystack.Config `description:"Settings for Haystack." json:"haystack,omitempty" toml:"haystack,omitempty" yaml:"haystack,omitempty" export:"true" label:"allowEmpty"`
+	Elastic       *elastic.Config  `description:"Settings for Elastic." json:"elastic,omitempty" toml:"elastic,omitempty" yaml:"elastic,omitempty" export:"true" label:"allowEmpty"`
 }
 
 // SetDefaults sets the default values.

pkg/server/middleware/chainbuilder.go

@@ -108,6 +108,14 @@ func setupTracing(conf *static.Tracing) *tracing.Tracing {
 		}
 	}
 
+	if conf.Elastic != nil {
+		if backend != nil {
+			log.WithoutContext().Error("Multiple tracing backend are not supported: cannot create Elastic backend.")
+		} else {
+			backend = conf.Elastic
+		}
+	}
+
 	if backend == nil {
 		log.WithoutContext().Debug("Could not initialize tracing, using Jaeger by default")
 		defaultBackend := &jaeger.Config{}

pkg/tracing/elastic/elastic.go

@@ -0,0 +1,64 @@
+package elastic
+
+import (
+	"io"
+	"net/url"
+
+	"github.com/containous/traefik/v2/pkg/log"
+	"github.com/containous/traefik/v2/pkg/version"
+	"github.com/opentracing/opentracing-go"
+	"go.elastic.co/apm"
+	"go.elastic.co/apm/module/apmot"
+	"go.elastic.co/apm/transport"
+)
+
+// Name sets the name of this tracer.
+const Name = "elastic"
+
+// Config provides configuration settings for a elastic.co tracer.
+type Config struct {
+	ServerURL          string `description:"Set the URL of the Elastic APM server." json:"serverURL,omitempty" toml:"serverURL,omitempty" yaml:"serverURL,omitempty"`
+	SecretToken        string `description:"Set the token used to connect to Elastic APM Server." json:"secretToken,omitempty" toml:"secretToken,omitempty" yaml:"secretToken,omitempty"`
+	ServiceEnvironment string `description:"Set the name of the environment Traefik is deployed in, e.g. 'production' or 'staging'." json:"serviceEnvironment,omitempty" toml:"serviceEnvironment,omitempty" yaml:"serviceEnvironment,omitempty"`
+}
+
+// Setup sets up the tracer.
+func (c *Config) Setup(serviceName string) (opentracing.Tracer, io.Closer, error) {
+	// Create default transport.
+	tr, err := transport.NewHTTPTransport()
+	if err != nil {
+		return nil, nil, err
+	}
+
+	if c.ServerURL != "" {
+		serverURL, err := url.Parse(c.ServerURL)
+		if err != nil {
+			return nil, nil, err
+		}
+		tr.SetServerURL(serverURL)
+	}
+
+	if c.SecretToken != "" {
+		tr.SetSecretToken(c.SecretToken)
+	}
+
+	tracer, err := apm.NewTracerOptions(apm.TracerOptions{
+		ServiceName:        serviceName,
+		ServiceVersion:     version.Version,
+		ServiceEnvironment: c.ServiceEnvironment,
+		Transport:          tr,
+	})
+	if err != nil {
+		return nil, nil, err
+	}
+
+	tracer.SetLogger(log.WithoutContext())
+	otTracer := apmot.New(apmot.WithTracer(tracer))
+
+	// Without this, child spans are getting the NOOP tracer
+	opentracing.SetGlobalTracer(otTracer)
+
+	log.WithoutContext().Debug("Elastic tracer configured")
+
+	return otTracer, nil, nil
+}