Move away from global tracers. (#6591)

* Move away from global tracers.

This PR moves away from global tracers and instead initialises
a tracer provider at Service setup and passes it where it needs to be.

* Change tracing provider to be set via options.

Also change name for GetServiceTraceProvider.

* Add changelog.

services/proxy/pkg/middleware/authentication.go

@@ -8,7 +8,6 @@ import (
 	"strings"
 
 	"github.com/owncloud/ocis/v2/services/proxy/pkg/router"
-	proxytracing "github.com/owncloud/ocis/v2/services/proxy/pkg/tracing"
 	"github.com/owncloud/ocis/v2/services/proxy/pkg/webdav"
 	"go.opentelemetry.io/otel/trace"
 	"golang.org/x/text/cases"
@@ -50,7 +49,8 @@ type Authenticator interface {
 func Authentication(auths []Authenticator, opts ...Option) func(next http.Handler) http.Handler {
 	options := newOptions(opts...)
 	configureSupportedChallenges(options)
-	tracer := proxytracing.TraceProvider.Tracer("proxy")
+	tracer := getTraceProvider(options).Tracer("proxy")
+
 	spanOpts := []trace.SpanStartOption{
 		trace.WithSpanKind(trace.SpanKindServer),
 	}
@@ -206,3 +206,10 @@ func evalRequestURI(l userAgentLocker, r regexp.Regexp) {
 	}
 	l.w.Header().Add(WwwAuthenticate, fmt.Sprintf("%v realm=\"%s\", charset=\"UTF-8\"", caser.String(l.fallback), l.r.Host))
 }
+
+func getTraceProvider(o Options) trace.TracerProvider {
+	if o.TraceProvider != nil {
+		return o.TraceProvider
+	}
+	return trace.NewNoopTracerProvider()
+}

services/proxy/pkg/middleware/options.go

@@ -14,6 +14,7 @@ import (
 	"github.com/owncloud/ocis/v2/services/proxy/pkg/user/backend"
 	"github.com/owncloud/ocis/v2/services/proxy/pkg/userroles"
 	store "go-micro.dev/v4/store"
+	"go.opentelemetry.io/otel/trace"
 )
 
 // Option defines a single option function.
@@ -67,6 +68,8 @@ type Options struct {
 	// RoleQuotas hold userid:quota mappings. These will be used when provisioning new users.
 	// The users will get as much quota as is set for their role.
 	RoleQuotas map[string]uint64
+	// TraceProvider sets the tracing provider.
+	TraceProvider trace.TracerProvider
 }
 
 // newOptions initializes the available default options.
@@ -226,3 +229,10 @@ func RoleQuotas(roleQuotas map[string]uint64) Option {
 		o.RoleQuotas = roleQuotas
 	}
 }
+
+// TraceProvider sets the tracing provider.
+func TraceProvider(tp trace.TracerProvider) Option {
+	return func(o *Options) {
+		o.TraceProvider = tp
+	}
+}

services/proxy/pkg/middleware/tracing.go

@@ -6,23 +6,24 @@ import (
 
 	chimiddleware "github.com/go-chi/chi/v5/middleware"
 	pkgtrace "github.com/owncloud/ocis/v2/ocis-pkg/tracing"
-	proxytracing "github.com/owncloud/ocis/v2/services/proxy/pkg/tracing"
 	"go.opentelemetry.io/otel/attribute"
 	"go.opentelemetry.io/otel/propagation"
 	"go.opentelemetry.io/otel/trace"
 )
 
 // Tracer provides a middleware to start traces
-func Tracer() func(next http.Handler) http.Handler {
+func Tracer(tp trace.TracerProvider) func(next http.Handler) http.Handler {
 	return func(next http.Handler) http.Handler {
 		return &tracer{
-			next: next,
+			next:          next,
+			traceProvider: tp,
 		}
 	}
 }
 
 type tracer struct {
-	next http.Handler
+	next          http.Handler
+	traceProvider trace.TracerProvider
 }
 
 func (m tracer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
@@ -31,7 +32,7 @@ func (m tracer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 		span trace.Span
 	)
 
-	tracer := proxytracing.TraceProvider.Tracer("proxy")
+	tracer := m.traceProvider.Tracer("proxy")
 	spanOpts := []trace.SpanStartOption{
 		trace.WithSpanKind(trace.SpanKindServer),
 	}