Add otel tracing implementation support

docs/reference/plugins.md

@@ -430,18 +430,11 @@ func (g *geoip) Match(r *http.Request) bool {
 }
 ```
 
-## OpenTracing plugins
+## Tracing plugins
 
 The tracers, except for `noop`, are built as Go Plugins. A tracing plugin can
 be loaded with `-opentracing NAME` as parameter to skipper.
 
-Implementations of OpenTracing API can be found in the
-https://github.com/skipper-plugins/opentracing repository.
-
-All plugins must have a function named `InitTracer` with the following signature
-
-    func([]string) (opentracing.Tracer, error)
-
 The parameters passed are all arguments for the plugin, i.e. everything after the first
 word from skipper's -opentracing parameter. E.g. when the -opentracing parameter is
 `mytracer foo=bar token=xxx somename=bla:3` the "mytracer" plugin will receive
@@ -452,6 +445,24 @@ as arguments.
 
 The tracer plugin implementation is responsible to parse the received arguments.
 
+Tracer plugins need to follow either OpenTelemetry specification or OpenTracing specification. OpenTelemetry is preferable since OpenTracing will be deprecated in the next few months.
+
+### OpenTelemetry
+
+All opentelemetry plugins must have a function named `InitTracer` with the following signature
+
+    func([]string) (opentelemetry.Tracer, error)
+
+### OpenTracing
+
+Implementations of OpenTracing API can be found in the
+https://github.com/skipper-plugins/opentracing repository.
+
+All opentracing plugins must have a function named `InitTracer` with the following signature
+
+    func([]string) (opentracing.Tracer, error)
+
+
 An example plugin looks like
 ```go
 package main

docs/tutorials/development.md

@@ -280,13 +280,26 @@ delay between the calls.
 A complete example is the [routestring implementation](https://github.com/zalando/skipper/blob/master/dataclients/routestring/string.go), which fits in
 less than 50 lines of code.
 
-## Opentracing
+## Tracing
+
+Currently Skipper supports both Opentelemetry and Opentracing as tracing options. Opentracing is soon to be deprecated in favor of Opentelemetry.
+
+Please check the [tracing package](https://github.com/zalando/skipper/blob/master/tracing)
+and ask for further guidance in our [community channels](https://github.com/zalando/skipper#community).
+
+### Opentelemetry
+
+Your custom Opentelemetry implementations need to satisfy the `opentelemetry.Tracer` interface from
+https://github.com/open-telemetry/opentelemetry-go and need to be loaded as
+a plugin, which might change in the future.
+
+### Opentracing
 
 Your custom Opentracing implementations need to satisfy the `opentracing.Tracer` interface from
 https://github.com/opentracing/opentracing-go and need to be loaded as
 a plugin, which might change in the future.
-Please check the [tracing package](https://github.com/zalando/skipper/blob/master/tracing)
-and ask for further guidance in our [community channels](https://github.com/zalando/skipper#community).
+
+Currently Skipper is migrating to Opentelemetry, what this means is, when this plugin is loaded it will be wrapped in a type called [TracerWrapper](https://github.com/zalando/skipper/blob/master/tracing/wrappers.go), this type implements `opentelemetry.Tracer` interface, and under the hood converts these function calls to `opentracing.Tracer` calls. In the future skipper will only accept plugins that return `opentelemetry.Tracer`.
 
 ## Core
 

filters/auth/authclient.go

@@ -10,9 +10,10 @@ import (
 	"strings"
 	"time"
 
-	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
 	"github.com/zalando/skipper/net"
+	"go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace/noop"
 )
 
 const (
@@ -36,9 +37,9 @@ type tokeninfoClient interface {
 
 var _ tokeninfoClient = &authClient{}
 
-func newAuthClient(baseURL, spanName string, timeout time.Duration, maxIdleConns int, tracer opentracing.Tracer) (*authClient, error) {
+func newAuthClient(baseURL, spanName string, timeout time.Duration, maxIdleConns int, tracer trace.Tracer) (*authClient, error) {
 	if tracer == nil {
-		tracer = opentracing.NoopTracer{}
+		tracer = noop.NewTracerProvider().Tracer("Noop tracer")
 	}
 	if maxIdleConns <= 0 {
 		maxIdleConns = defaultMaxIdleConns
@@ -53,7 +54,7 @@ func newAuthClient(baseURL, spanName string, timeout time.Duration, maxIdleConns
 		ResponseHeaderTimeout:   timeout,
 		TLSHandshakeTimeout:     timeout,
 		MaxIdleConnsPerHost:     maxIdleConns,
-		Tracer:                  tracer,
+		OtelTracer:              tracer,
 		OpentracingComponentTag: "skipper",
 		OpentracingSpanName:     spanName,
 	})

filters/auth/grantconfig.go

@@ -9,11 +9,11 @@ import (
 	"strings"
 	"time"
 
-	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
 	snet "github.com/zalando/skipper/net"
 	"github.com/zalando/skipper/routing"
 	"github.com/zalando/skipper/secrets"
+	"go.opentelemetry.io/otel/trace"
 	"golang.org/x/oauth2"
 )
 
@@ -119,8 +119,10 @@ type OAuthConfig struct {
 	// MaxIdleConnectionsPerHost used for tokeninfo, access-token and refresh-token endpoint.
 	MaxIdleConnectionsPerHost int
 
-	// Tracer used for tokeninfo, access-token and refresh-token endpoint.
-	Tracer opentracing.Tracer
+	// Tracer is an abstraction around different tracers. Currently skipper can
+	// operate both with OpenTracing and OpenTelemetry. This tracer traces the communication
+	// with access-token and refresh-token endpoints.
+	Tracer trace.Tracer
 }
 
 var (
@@ -188,7 +190,7 @@ func (c *OAuthConfig) Init() error {
 			ResponseHeaderTimeout:   c.ConnectionTimeout,
 			TLSHandshakeTimeout:     c.ConnectionTimeout,
 			MaxIdleConnsPerHost:     c.MaxIdleConnectionsPerHost,
-			Tracer:                  c.Tracer,
+			OtelTracer:              c.Tracer,
 			OpentracingComponentTag: "skipper",
 			OpentracingSpanName:     "grantauth",
 		})

filters/auth/oidc.go

@@ -20,12 +20,12 @@ import (
 	"time"
 
 	"github.com/coreos/go-oidc"
-	"github.com/opentracing/opentracing-go"
 	log "github.com/sirupsen/logrus"
 	"github.com/tidwall/gjson"
 	"github.com/zalando/skipper/filters"
 	snet "github.com/zalando/skipper/net"
 	"github.com/zalando/skipper/secrets"
+	"go.opentelemetry.io/otel/trace"
 	"golang.org/x/oauth2"
 )
 
@@ -91,7 +91,7 @@ type OidcOptions struct {
 	MaxIdleConns   int
 	CookieValidity time.Duration
 	Timeout        time.Duration
-	Tracer         opentracing.Tracer
+	Tracer         trace.Tracer
 }
 
 type (
@@ -1032,7 +1032,7 @@ func (f *tokenOidcFilter) initClient() *snet.Client {
 		ResponseHeaderTimeout:   f.oidcOptions.Timeout,
 		TLSHandshakeTimeout:     f.oidcOptions.Timeout,
 		MaxIdleConnsPerHost:     f.oidcOptions.MaxIdleConns,
-		Tracer:                  f.oidcOptions.Tracer,
+		OtelTracer:              f.oidcOptions.Tracer,
 		OpentracingComponentTag: "skipper",
 		OpentracingSpanName:     "distributedClaims",
 	})

filters/auth/tokeninfo.go

@@ -5,8 +5,8 @@ import (
 	"strings"
 	"time"
 
-	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
+	"go.opentelemetry.io/otel/trace"
 )
 
 const (
@@ -26,7 +26,7 @@ type TokeninfoOptions struct {
 	URL          string
 	Timeout      time.Duration
 	MaxIdleConns int
-	Tracer       opentracing.Tracer
+	Tracer       trace.Tracer
 
 	// CacheSize configures the maximum number of cached tokens.
 	// The cache evicts least recently used items first.

filters/auth/tokenintrospection.go

@@ -11,6 +11,8 @@ import (
 
 	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
+	"github.com/zalando/skipper/tracing"
+	"go.opentelemetry.io/otel/trace"
 )
 
 const (
@@ -37,7 +39,7 @@ const (
 
 type TokenintrospectionOptions struct {
 	Timeout      time.Duration
-	Tracer       opentracing.Tracer
+	Tracer       trace.Tracer
 	MaxIdleConns int
 }
 
@@ -173,7 +175,7 @@ func NewSecureOAuthTokenintrospectionAllClaims(timeout time.Duration) filters.Sp
 // NewOAuthTokenintrospectionAnyClaims, NewOAuthTokenintrospectionAllClaims,
 // NewSecureOAuthTokenintrospectionAnyKV, NewSecureOAuthTokenintrospectionAllKV,
 // NewSecureOAuthTokenintrospectionAnyClaims, NewSecureOAuthTokenintrospectionAllClaims,
-// pass opentracing.Tracer and other options in TokenintrospectionOptions.
+// pass open telemetry Tracer and other options in TokenintrospectionOptions.
 func TokenintrospectionWithOptions(
 	create func(time.Duration) filters.Spec,
 	o TokenintrospectionOptions,
@@ -193,7 +195,7 @@ func newOAuthTokenintrospectionFilter(typ roleCheckType, timeout time.Duration)
 		typ: typ,
 		options: TokenintrospectionOptions{
 			Timeout: timeout,
-			Tracer:  opentracing.NoopTracer{},
+			Tracer:  &tracing.TracerWrapper{Ot: opentracing.NoopTracer{}},
 		},
 		secure: false,
 	}
@@ -204,7 +206,7 @@ func newSecureOAuthTokenintrospectionFilter(typ roleCheckType, timeout time.Dura
 		typ: typ,
 		options: TokenintrospectionOptions{
 			Timeout: timeout,
-			Tracer:  opentracing.NoopTracer{},
+			Tracer:  &tracing.TracerWrapper{Ot: opentracing.NoopTracer{}},
 		},
 		secure: true,
 	}

filters/auth/webhook.go

@@ -7,9 +7,11 @@ import (
 	"time"
 
 	"github.com/opentracing/opentracing-go"
+	"go.opentelemetry.io/otel/trace"
 	"golang.org/x/net/http/httpguts"
 
 	"github.com/zalando/skipper/filters"
+	"github.com/zalando/skipper/tracing"
 )
 
 const (
@@ -20,7 +22,7 @@ const (
 type WebhookOptions struct {
 	Timeout      time.Duration
 	MaxIdleConns int
-	Tracer       opentracing.Tracer
+	Tracer       trace.Tracer
 }
 
 type (
@@ -39,7 +41,10 @@ var webhookAuthClient map[string]*authClient = make(map[string]*authClient)
 // to validate authorization for requests via an
 // external web hook.
 func NewWebhook(timeout time.Duration) filters.Spec {
-	return WebhookWithOptions(WebhookOptions{Timeout: timeout, Tracer: opentracing.NoopTracer{}})
+	return WebhookWithOptions(WebhookOptions{
+		Timeout: timeout,
+		Tracer:  &tracing.TracerWrapper{Ot: opentracing.NoopTracer{}},
+	})
 }
 
 // WebhookWithOptions creates a new auth filter specification

filters/filters.go

@@ -8,7 +8,7 @@ import (
 
 	log "github.com/sirupsen/logrus"
 
-	"github.com/opentracing/opentracing-go"
+	"go.opentelemetry.io/otel/trace"
 )
 
 const (
@@ -48,6 +48,10 @@ type FilterContext interface {
 	// with its properties changed by the filters.
 	Request() *http.Request
 
+	// Set a new request object in the context. This is useful when its necessary to make small changes
+	// to the request, like set a new request context.
+	WithRequest(*http.Request)
+
 	// The response object. It is returned to the client with its
 	// properties changed by the filters.
 	Response() *http.Response
@@ -107,11 +111,11 @@ type FilterContext interface {
 	// Allow filters to collect metrics other than the default metrics (Filter Request, Filter Response methods)
 	Metrics() Metrics
 
-	// Allow filters to add Tags, Baggage to the trace or set the ComponentName.
-	Tracer() opentracing.Tracer
+	// Allow filters to add Tags, Baggage to open tracing trace or set the ComponentName.
+	Tracer() trace.Tracer
 
-	// Allow filters to create their own spans
-	ParentSpan() opentracing.Span
+	// Allow filters to create their own open tracing spans
+	ParentSpan() trace.Span
 
 	// Returns a clone of the FilterContext including a brand new request object.
 	// The stream body of the new request is shared with the original.

filters/filtertest/filtertest.go

@@ -7,8 +7,9 @@ package filtertest
 import (
 	"net/http"
 
-	"github.com/opentracing/opentracing-go"
 	"github.com/zalando/skipper/filters"
+	"go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace/noop"
 
 	log "github.com/sirupsen/logrus"
 )
@@ -33,7 +34,7 @@ type Context struct {
 	FBackendUrl         string
 	FOutgoingHost       string
 	FMetrics            filters.Metrics
-	FTracer             opentracing.Tracer
+	FTracer             trace.Tracer
 }
 
 func (spec *Filter) Name() string                    { return spec.FilterName }
@@ -58,15 +59,16 @@ func (fc *Context) ResponseController() *http.ResponseController {
 	return http.NewResponseController(fc.FResponseWriter)
 }
 
-func (fc *Context) Tracer() opentracing.Tracer {
+func (fc *Context) Tracer() trace.Tracer {
 	if fc.FTracer != nil {
 		return fc.FTracer
 	}
-	return &opentracing.NoopTracer{}
+	return noop.NewTracerProvider().Tracer("Noop tracer - filtertest")
 }
 
-func (fc *Context) ParentSpan() opentracing.Span {
-	return opentracing.StartSpan("test_span")
+func (fc *Context) ParentSpan() trace.Span {
+	_, span := fc.FTracer.Start(fc.FRequest.Context(), "test_span")
+	return span
 }
 
 func (fc *Context) Logger() filters.FilterContextLogger {
@@ -79,6 +81,10 @@ func (fc *Context) Serve(resp *http.Response) {
 	fc.FServed = true
 }
 
+func (fc *Context) WithRequest(r *http.Request) {
+	fc.FRequest = r
+}
+
 //lint:ignore ST1016 ignore receiver name, because of type reuse
 func (spec *Filter) CreateFilter(config []interface{}) (filters.Filter, error) {
 	return &Filter{spec.FilterName, config}, nil

filters/openpolicyagent/evaluation.go

@@ -12,10 +12,11 @@ import (
 	"github.com/open-policy-agent/opa/rego"
 	"github.com/open-policy-agent/opa/server"
 	"github.com/open-policy-agent/opa/tracing"
-	"github.com/opentracing/opentracing-go"
+	"go.opentelemetry.io/otel/attribute"
+	"go.opentelemetry.io/otel/trace"
 )
 
-func (opa *OpenPolicyAgentInstance) Eval(ctx context.Context, req *ext_authz_v3.CheckRequest) (*envoyauth.EvalResult, error) {
+func (opa *OpenPolicyAgentInstance) Eval(ctx context.Context, span trace.Span, req *ext_authz_v3.CheckRequest) (*envoyauth.EvalResult, error) {
 
 	decisionId, err := opa.idGenerator.Generate()
 	if err != nil {
@@ -29,9 +30,8 @@ func (opa *OpenPolicyAgentInstance) Eval(ctx context.Context, req *ext_authz_v3.
 		return nil, err
 	}
 
-	span := opentracing.SpanFromContext(ctx)
 	if span != nil {
-		span.SetTag("opa.decision_id", result.DecisionID)
+		span.SetAttributes(attribute.String("opa.decision_id", result.DecisionID))
 	}
 
 	var input map[string]interface{}