[chore] Simplify the OTEL setup (#4110)

# Description

This simplifies our OTEL setup by:

* Getting rid of some deprecated things.
* Using `autoexport` and letting things get configured by the `OTEL_` environment variables.
* Removing all the unnecessary config options.

## Checklist

Please put an x inside each checkbox to indicate that you've read and followed it: `[ ]` -> `[x]`

If this is a documentation change, only the first checkbox must be filled (you can delete the others if you want).

- [x] I/we have read the [GoToSocial contribution guidelines](https://codeberg.org/superseriousbusiness/gotosocial/src/branch/main/CONTRIBUTING.md).
- [x] I/we have discussed the proposed changes already, either in an issue on the repository, or in the Matrix chat.
- [x] I/we have not leveraged AI to create the proposed changes.
- [x] I/we have performed a self-review of added code.
- [x] I/we have written code that is legible and maintainable by others.
- [ ] I/we have commented the added code, particularly in hard-to-understand areas.
- [x] I/we have made any necessary changes to documentation.
- [ ] I/we have added tests that cover new code.
- [x] I/we have run tests and they pass locally with the changes.
- [x] I/we have run `go fmt ./...` and `golangci-lint run`.

Reviewed-on: https://codeberg.org/superseriousbusiness/gotosocial/pulls/4110
Reviewed-by: tobi <kipvandenbos@noreply.codeberg.org>
Co-authored-by: Daenney <daenney@noreply.codeberg.org>
Co-committed-by: Daenney <daenney@noreply.codeberg.org>

internal/observability/metrics.go

@@ -21,46 +21,32 @@ package observability
 
 import (
 	"context"
-	"errors"
+	"fmt"
 
 	"code.superseriousbusiness.org/gotosocial/internal/config"
 	"code.superseriousbusiness.org/gotosocial/internal/db"
 
 	"github.com/gin-gonic/gin"
 	"github.com/technologize/otel-go-contrib/otelginmetrics"
+	"go.opentelemetry.io/contrib/exporters/autoexport"
 	"go.opentelemetry.io/otel"
-	"go.opentelemetry.io/otel/exporters/prometheus"
 	"go.opentelemetry.io/otel/metric"
 	sdk "go.opentelemetry.io/otel/sdk/metric"
 	"go.opentelemetry.io/otel/sdk/metric/exemplar"
-	"go.opentelemetry.io/otel/sdk/resource"
-	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
 )
 
-const (
-	serviceName = "GoToSocial"
-)
-
-func InitializeMetrics(db db.DB) error {
+func InitializeMetrics(ctx context.Context, db db.DB) error {
 	if !config.GetMetricsEnabled() {
 		return nil
 	}
 
-	if config.GetMetricsAuthEnabled() {
-		if config.GetMetricsAuthPassword() == "" || config.GetMetricsAuthUsername() == "" {
-			return errors.New("metrics-auth-username and metrics-auth-password must be set when metrics-auth-enabled is true")
-		}
+	r, err := Resource()
+	if err != nil {
+		// this can happen if semconv versioning is out-of-sync
+		return fmt.Errorf("building tracing resource: %w", err)
 	}
 
-	r, _ := resource.Merge(
-		resource.Default(),
-		resource.NewSchemaless(
-			semconv.ServiceName(serviceName),
-			semconv.ServiceVersion(config.GetSoftwareVersion()),
-		),
-	)
-
-	prometheusExporter, err := prometheus.New()
+	mt, err := autoexport.NewMetricReader(ctx)
 	if err != nil {
 		return err
 	}
@@ -68,7 +54,7 @@ func InitializeMetrics(db db.DB) error {
 	meterProvider := sdk.NewMeterProvider(
 		sdk.WithExemplarFilter(exemplar.AlwaysOffFilter),
 		sdk.WithResource(r),
-		sdk.WithReader(prometheusExporter),
+		sdk.WithReader(mt),
 	)
 
 	otel.SetMeterProvider(meterProvider)

internal/observability/otel.go

@@ -0,0 +1,40 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+//go:build !nootel
+
+package observability
+
+import (
+	"code.superseriousbusiness.org/gotosocial/internal/config"
+	"go.opentelemetry.io/otel/sdk/resource"
+	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
+)
+
+const (
+	serviceName = "GoToSocial"
+)
+
+func Resource() (*resource.Resource, error) {
+	return resource.Merge(
+		resource.Default(),
+		resource.NewSchemaless(
+			semconv.ServiceName(serviceName),
+			semconv.ServiceVersion(config.GetSoftwareVersion()),
+		),
+	)
+}

internal/observability/tracing.go

@@ -22,19 +22,21 @@ package observability
 import (
 	"context"
 	"fmt"
+	"net"
+	"net/http"
+	"strconv"
 
 	"codeberg.org/gruf/go-kv"
+
 	"github.com/gin-gonic/gin"
+
+	"go.opentelemetry.io/contrib/exporters/autoexport"
 	"go.opentelemetry.io/otel"
 	"go.opentelemetry.io/otel/attribute"
-	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
-	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
 	"go.opentelemetry.io/otel/propagation"
-	"go.opentelemetry.io/otel/sdk/resource"
-	"go.opentelemetry.io/otel/sdk/trace"
-	"go.opentelemetry.io/otel/semconv/v1.20.0/httpconv"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
 	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
-	oteltrace "go.opentelemetry.io/otel/trace"
+	"go.opentelemetry.io/otel/trace"
 
 	"code.superseriousbusiness.org/gotosocial/internal/config"
 	"code.superseriousbusiness.org/gotosocial/internal/gtscontext"
@@ -46,66 +48,35 @@ const (
 	tracerName = "code.superseriousbusiness.org/gotosocial/internal/observability"
 )
 
-func InitializeTracing() error {
+func InitializeTracing(ctx context.Context) error {
 	if !config.GetTracingEnabled() {
 		return nil
 	}
 
-	insecure := config.GetTracingInsecureTransport()
-
-	var tpo trace.TracerProviderOption
-	switch config.GetTracingTransport() {
-	case "grpc":
-		opts := []otlptracegrpc.Option{
-			otlptracegrpc.WithEndpoint(config.GetTracingEndpoint()),
-		}
-		if insecure {
-			opts = append(opts, otlptracegrpc.WithInsecure())
-		}
-		exp, err := otlptracegrpc.New(context.Background(), opts...)
-		if err != nil {
-			return fmt.Errorf("building tracing exporter: %w", err)
-		}
-		tpo = trace.WithBatcher(exp)
-	case "http":
-		opts := []otlptracehttp.Option{
-			otlptracehttp.WithEndpoint(config.GetTracingEndpoint()),
-		}
-		if insecure {
-			opts = append(opts, otlptracehttp.WithInsecure())
-		}
-		exp, err := otlptracehttp.New(context.Background(), opts...)
-		if err != nil {
-			return fmt.Errorf("building tracing exporter: %w", err)
-		}
-		tpo = trace.WithBatcher(exp)
-	default:
-		return fmt.Errorf("invalid tracing transport: %s", config.GetTracingTransport())
-	}
-	r, err := resource.Merge(
-		resource.Default(),
-		resource.NewSchemaless(
-			semconv.ServiceName("GoToSocial"),
-			semconv.ServiceVersion(config.GetSoftwareVersion()),
-		),
-	)
+	r, err := Resource()
 	if err != nil {
 		// this can happen if semconv versioning is out-of-sync
 		return fmt.Errorf("building tracing resource: %w", err)
 	}
 
-	tp := trace.NewTracerProvider(
-		tpo,
-		trace.WithResource(r),
+	se, err := autoexport.NewSpanExporter(ctx)
+	if err != nil {
+		return err
+	}
+
+	tp := sdktrace.NewTracerProvider(
+		sdktrace.WithResource(r),
+		sdktrace.WithBatcher(se),
 	)
+
 	otel.SetTracerProvider(tp)
-	propagator := propagation.NewCompositeTextMapPropagator(
+	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(
 		propagation.TraceContext{},
 		propagation.Baggage{},
-	)
-	otel.SetTextMapPropagator(propagator)
+	))
+
 	log.Hook(func(ctx context.Context, kvs []kv.Field) []kv.Field {
-		span := oteltrace.SpanFromContext(ctx)
+		span := trace.SpanFromContext(ctx)
 		if span != nil && span.SpanContext().HasTraceID() {
 			return append(kvs, kv.Field{K: "traceID", V: span.SpanContext().TraceID().String()})
 		}
@@ -121,7 +92,7 @@ func TracingMiddleware() gin.HandlerFunc {
 	provider := otel.GetTracerProvider()
 	tracer := provider.Tracer(
 		tracerName,
-		oteltrace.WithInstrumentationVersion(config.GetSoftwareVersion()),
+		trace.WithInstrumentationVersion(config.GetSoftwareVersion()),
 	)
 	propagator := otel.GetTextMapPropagator()
 	return func(c *gin.Context) {
@@ -140,16 +111,16 @@ func TracingMiddleware() gin.HandlerFunc {
 			c.Request = c.Request.WithContext(savedCtx)
 		}()
 		ctx := propagator.Extract(savedCtx, propagation.HeaderCarrier(c.Request.Header))
-		opts := []oteltrace.SpanStartOption{
-			oteltrace.WithAttributes(httpconv.ServerRequest(config.GetHost(), c.Request)...),
-			oteltrace.WithSpanKind(oteltrace.SpanKindServer),
+		opts := []trace.SpanStartOption{
+			trace.WithAttributes(ServerRequestAttributes(c.Request)...),
+			trace.WithSpanKind(trace.SpanKindServer),
 		}
 
 		rAttr := semconv.HTTPRoute(spanName)
-		opts = append(opts, oteltrace.WithAttributes(rAttr))
+		opts = append(opts, trace.WithAttributes(rAttr))
 		id := gtscontext.RequestID(c.Request.Context())
 		if id != "" {
-			opts = append(opts, oteltrace.WithAttributes(attribute.String("requestID", id)))
+			opts = append(opts, trace.WithAttributes(attribute.String("requestID", id)))
 		}
 		ctx, span := tracer.Start(ctx, spanName, opts...)
 		defer span.End()
@@ -161,7 +132,6 @@ func TracingMiddleware() gin.HandlerFunc {
 		c.Next()
 
 		status := c.Writer.Status()
-		span.SetStatus(httpconv.ServerStatus(status))
 		if status > 0 {
 			span.SetAttributes(semconv.HTTPResponseStatusCode(status))
 		}
@@ -175,8 +145,52 @@ func InjectRequestID() gin.HandlerFunc {
 	return func(c *gin.Context) {
 		id := gtscontext.RequestID(c.Request.Context())
 		if id != "" {
-			span := oteltrace.SpanFromContext(c.Request.Context())
+			span := trace.SpanFromContext(c.Request.Context())
 			span.SetAttributes(attribute.String("requestID", id))
 		}
 	}
 }
+
+func ServerRequestAttributes(req *http.Request) []attribute.KeyValue {
+	attrs := make([]attribute.KeyValue, 0, 8)
+	attrs = append(attrs, method(req.Method))
+	attrs = append(attrs, semconv.URLFull(req.URL.RequestURI()))
+	attrs = append(attrs, semconv.URLScheme(req.URL.Scheme))
+	attrs = append(attrs, semconv.UserAgentOriginal(req.UserAgent()))
+	attrs = append(attrs, semconv.NetworkProtocolName("http"))
+	attrs = append(attrs, semconv.NetworkProtocolVersion(fmt.Sprintf("%d:%d", req.ProtoMajor, req.ProtoMinor)))
+
+	if ip, port, err := net.SplitHostPort(req.RemoteAddr); err == nil {
+		iport, _ := strconv.Atoi(port)
+		attrs = append(attrs,
+			semconv.NetworkPeerAddress(ip),
+			semconv.NetworkPeerPort(iport),
+		)
+	} else if req.RemoteAddr != "" {
+		attrs = append(attrs,
+			semconv.NetworkPeerAddress(req.RemoteAddr),
+		)
+	}
+
+	return attrs
+}
+
+func method(m string) attribute.KeyValue {
+	var methodLookup = map[string]attribute.KeyValue{
+		http.MethodConnect: semconv.HTTPRequestMethodConnect,
+		http.MethodDelete:  semconv.HTTPRequestMethodDelete,
+		http.MethodGet:     semconv.HTTPRequestMethodGet,
+		http.MethodHead:    semconv.HTTPRequestMethodHead,
+		http.MethodOptions: semconv.HTTPRequestMethodOptions,
+		http.MethodPatch:   semconv.HTTPRequestMethodPatch,
+		http.MethodPost:    semconv.HTTPRequestMethodPost,
+		http.MethodPut:     semconv.HTTPRequestMethodPut,
+		http.MethodTrace:   semconv.HTTPRequestMethodTrace,
+	}
+
+	if kv, ok := methodLookup[m]; ok {
+		return kv
+	}
+
+	return semconv.HTTPRequestMethodGet
+}