Add OTel distributed tracing to backend, ui, and runner

Go backend:
- Add OTel SDK + otelhttp middleware deps (go.mod)
- New internal/otelsetup package: init OTLP/HTTP TracerProvider from env vars
- cmd/backend/main.go: call otelsetup.Init() after logger + ctx setup
- internal/backend/server.go: wrap mux with otelhttp.NewHandler() before
  sentryhttp, so all HTTP spans are recorded

SvelteKit UI:
- Add @opentelemetry/sdk-node, exporter-trace-otlp-http, resources,
  semantic-conventions
- hooks.server.ts: init NodeSDK when OTEL_EXPORTER_OTLP_ENDPOINT is set;
  graceful shutdown on SIGTERM/SIGINT

Config:
- docker-compose.yml: pass OTEL_EXPORTER_OTLP_ENDPOINT + OTEL_SERVICE_NAME
  to backend, runner, and ui services
- homelab/docker-compose.yml: fix runner OTel endpoint to HTTP port 4318
- Doppler prd: OTEL_EXPORTER_OTLP_ENDPOINT=https://otel.libnovel.cc
- Doppler prd_homelab: OTEL_EXPORTER_OTLP_ENDPOINT=http://otel-collector:4318

All services no-op gracefully when the env var is unset (local dev).

backend/cmd/backend/main.go

@@ -26,6 +26,7 @@ import (
 	"github.com/libnovel/backend/internal/config"
 	"github.com/libnovel/backend/internal/kokoro"
 	"github.com/libnovel/backend/internal/meili"
+	"github.com/libnovel/backend/internal/otelsetup"
 	"github.com/libnovel/backend/internal/storage"
 )
 
@@ -70,6 +71,16 @@ func run() error {
 	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
 	defer stop()
 
+	// ── OpenTelemetry tracing ─────────────────────────────────────────────────
+	otelShutdown, err := otelsetup.Init(ctx, version)
+	if err != nil {
+		return fmt.Errorf("init otel: %w", err)
+	}
+	if otelShutdown != nil {
+		defer otelShutdown()
+		log.Info("otel tracing enabled", "endpoint", os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT"))
+	}
+
 	// ── Storage ──────────────────────────────────────────────────────────────
 	store, err := storage.NewStore(ctx, cfg, log)
 	if err != nil {

backend/go.mod

@@ -9,14 +9,19 @@ require (
 
 require (
 	github.com/andybalholm/brotli v1.1.1 // indirect
+	github.com/cenkalti/backoff/v5 v5.0.3 // indirect
 	github.com/cespare/xxhash/v2 v2.3.0 // indirect
 	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f // indirect
 	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/felixge/httpsnoop v1.0.4 // indirect
 	github.com/getsentry/sentry-go v0.43.0 // indirect
 	github.com/go-ini/ini v1.67.0 // indirect
+	github.com/go-logr/logr v1.4.3 // indirect
+	github.com/go-logr/stdr v1.2.2 // indirect
 	github.com/golang-jwt/jwt/v5 v5.3.1 // indirect
 	github.com/google/uuid v1.6.0 // indirect
+	github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 // indirect
 	github.com/klauspost/compress v1.18.2 // indirect
 	github.com/klauspost/cpuid/v2 v2.2.11 // indirect
 	github.com/klauspost/crc32 v1.3.0 // indirect
@@ -28,10 +33,23 @@ require (
 	github.com/redis/go-redis/v9 v9.18.0 // indirect
 	github.com/rs/xid v1.6.0 // indirect
 	github.com/tinylib/msgp v1.6.1 // indirect
+	go.opentelemetry.io/auto/sdk v1.2.1 // indirect
+	go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0 // indirect
+	go.opentelemetry.io/otel v1.42.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.42.0 // indirect
+	go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0 // indirect
+	go.opentelemetry.io/otel/metric v1.42.0 // indirect
+	go.opentelemetry.io/otel/sdk v1.42.0 // indirect
+	go.opentelemetry.io/otel/trace v1.42.0 // indirect
+	go.opentelemetry.io/proto/otlp v1.9.0 // indirect
 	go.uber.org/atomic v1.11.0 // indirect
 	go.yaml.in/yaml/v3 v3.0.4 // indirect
 	golang.org/x/crypto v0.48.0 // indirect
 	golang.org/x/sys v0.41.0 // indirect
 	golang.org/x/text v0.34.0 // indirect
+	google.golang.org/genproto/googleapis/api v0.0.0-20260209200024-4cfbd4190f57 // indirect
+	google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57 // indirect
+	google.golang.org/grpc v1.79.2 // indirect
+	google.golang.org/protobuf v1.36.11 // indirect
 	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

backend/go.sum

@@ -1,5 +1,7 @@
 github.com/andybalholm/brotli v1.1.1 h1:PR2pgnyFznKEugtsUo0xLdDop5SKXd5Qf5ysW+7XdTA=
 github.com/andybalholm/brotli v1.1.1/go.mod h1:05ib4cKhjx3OQYUY22hTVd34Bc8upXjOLL2rKwwZBoA=
+github.com/cenkalti/backoff/v5 v5.0.3 h1:ZN+IMa753KfX5hd8vVaMixjnqRZ3y8CuJKRKj1xcsSM=
+github.com/cenkalti/backoff/v5 v5.0.3/go.mod h1:rkhZdG3JZukswDf7f0cwqPNk4K0sa+F97BxZthm/crw=
 github.com/cespare/xxhash/v2 v2.3.0 h1:UL815xU9SqsFlibzuggzjXhog7bL6oX9BbNZnL2UFvs=
 github.com/cespare/xxhash/v2 v2.3.0/go.mod h1:VGX0DQ3Q6kWi7AoAeZDth3/j3BFtOZR5XLFGgcrjCOs=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
@@ -8,14 +10,23 @@ github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f h1:lO4WD4F/r
 github.com/dgryski/go-rendezvous v0.0.0-20200823014737-9f7001d12a5f/go.mod h1:cuUVRXasLTGF7a8hSLbxyZXjz+1KgoB3wDUb6vlszIc=
 github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
 github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/felixge/httpsnoop v1.0.4 h1:NFTV2Zj1bL4mc9sqWACXbQFVBBg2W3GPvqp8/ESS2Wg=
+github.com/felixge/httpsnoop v1.0.4/go.mod h1:m8KPJKqk1gH5J9DgRY2ASl2lWCfGKXixSwevea8zH2U=
 github.com/getsentry/sentry-go v0.43.0 h1:XbXLpFicpo8HmBDaInk7dum18G9KSLcjZiyUKS+hLW4=
 github.com/getsentry/sentry-go v0.43.0/go.mod h1:XDotiNZbgf5U8bPDUAfvcFmOnMQQceESxyKaObSssW0=
 github.com/go-ini/ini v1.67.0 h1:z6ZrTEZqSWOTyH2FlglNbNgARyHG8oLW9gMELqKr06A=
 github.com/go-ini/ini v1.67.0/go.mod h1:ByCAeIL28uOIIG0E3PJtZPDL8WnHpFKFOtgjp+3Ies8=
+github.com/go-logr/logr v1.2.2/go.mod h1:jdQByPbusPIv2/zmleS9BjJVeZ6kBagPoEUsqbVz/1A=
+github.com/go-logr/logr v1.4.3 h1:CjnDlHq8ikf6E492q6eKboGOC0T8CDaOvkHCIg8idEI=
+github.com/go-logr/logr v1.4.3/go.mod h1:9T104GzyrTigFIr8wt5mBrctHMim0Nb2HLGrmQ40KvY=
+github.com/go-logr/stdr v1.2.2 h1:hSWxHoqTgW2S2qGc0LTAI563KZ5YKYRhT3MFKZMbjag=
+github.com/go-logr/stdr v1.2.2/go.mod h1:mMo/vtBO5dYbehREoey6XUKy/eSumjCCveDpRre4VKE=
 github.com/golang-jwt/jwt/v5 v5.3.1 h1:kYf81DTWFe7t+1VvL7eS+jKFVWaUnK9cB1qbwn63YCY=
 github.com/golang-jwt/jwt/v5 v5.3.1/go.mod h1:fxCRLWMO43lRc8nhHWY6LGqRcf+1gQWArsqaEUEa5bE=
 github.com/google/uuid v1.6.0 h1:NIvaJDMOsjHA8n1jAhLSgzrAzy1Hgr+hNrb57e+94F0=
 github.com/google/uuid v1.6.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0 h1:HWRh5R2+9EifMyIHV7ZV+MIZqgz+PMpZ14Jynv3O2Zs=
+github.com/grpc-ecosystem/grpc-gateway/v2 v2.28.0/go.mod h1:JfhWUomR1baixubs02l85lZYYOm7LV6om4ceouMv45c=
 github.com/klauspost/compress v1.18.2 h1:iiPHWW0YrcFgpBYhsA6D1+fqHssJscY/Tm/y2Uqnapk=
 github.com/klauspost/compress v1.18.2/go.mod h1:R0h/fSBs8DE4ENlcrlib3PsXS61voFxhIs2DeRhCvJ4=
 github.com/klauspost/cpuid/v2 v2.0.1/go.mod h1:FInQzS24/EEf25PyTYn52gqo7WaD8xa0213Md/qVLRg=
@@ -45,6 +56,24 @@ github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu
 github.com/tinylib/msgp v1.6.1 h1:ESRv8eL3u+DNHUoSAAQRE50Hm162zqAnBoGv9PzScPY=
 github.com/tinylib/msgp v1.6.1/go.mod h1:RSp0LW9oSxFut3KzESt5Voq4GVWyS+PSulT77roAqEA=
 github.com/xyproto/randomstring v1.0.5/go.mod h1:rgmS5DeNXLivK7YprL0pY+lTuhNQW3iGxZ18UQApw/E=
+go.opentelemetry.io/auto/sdk v1.2.1 h1:jXsnJ4Lmnqd11kwkBV2LgLoFMZKizbCi5fNZ/ipaZ64=
+go.opentelemetry.io/auto/sdk v1.2.1/go.mod h1:KRTj+aOaElaLi+wW1kO/DZRXwkF4C5xPbEe3ZiIhN7Y=
+go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0 h1:OyrsyzuttWTSur2qN/Lm0m2a8yqyIjUVBZcxFPuXq2o=
+go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp v0.67.0/go.mod h1:C2NGBr+kAB4bk3xtMXfZ94gqFDtg/GkI7e9zqGh5Beg=
+go.opentelemetry.io/otel v1.42.0 h1:lSQGzTgVR3+sgJDAU/7/ZMjN9Z+vUip7leaqBKy4sho=
+go.opentelemetry.io/otel v1.42.0/go.mod h1:lJNsdRMxCUIWuMlVJWzecSMuNjE7dOYyWlqOXWkdqCc=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.42.0 h1:THuZiwpQZuHPul65w4WcwEnkX2QIuMT+UFoOrygtoJw=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace v1.42.0/go.mod h1:J2pvYM5NGHofZ2/Ru6zw/TNWnEQp5crgyDeSrYpXkAw=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0 h1:uLXP+3mghfMf7XmV4PkGfFhFKuNWoCvvx5wP/wOXo0o=
+go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp v1.42.0/go.mod h1:v0Tj04armyT59mnURNUJf7RCKcKzq+lgJs6QSjHjaTc=
+go.opentelemetry.io/otel/metric v1.42.0 h1:2jXG+3oZLNXEPfNmnpxKDeZsFI5o4J+nz6xUlaFdF/4=
+go.opentelemetry.io/otel/metric v1.42.0/go.mod h1:RlUN/7vTU7Ao/diDkEpQpnz3/92J9ko05BIwxYa2SSI=
+go.opentelemetry.io/otel/sdk v1.42.0 h1:LyC8+jqk6UJwdrI/8VydAq/hvkFKNHZVIWuslJXYsDo=
+go.opentelemetry.io/otel/sdk v1.42.0/go.mod h1:rGHCAxd9DAph0joO4W6OPwxjNTYWghRWmkHuGbayMts=
+go.opentelemetry.io/otel/trace v1.42.0 h1:OUCgIPt+mzOnaUTpOQcBiM/PLQ/Op7oq6g4LenLmOYY=
+go.opentelemetry.io/otel/trace v1.42.0/go.mod h1:f3K9S+IFqnumBkKhRJMeaZeNk9epyhnCmQh/EysQCdc=
+go.opentelemetry.io/proto/otlp v1.9.0 h1:l706jCMITVouPOqEnii2fIAuO3IVGBRPV5ICjceRb/A=
+go.opentelemetry.io/proto/otlp v1.9.0/go.mod h1:xE+Cx5E/eEHw+ISFkwPLwCZefwVjY+pqKg1qcK03+/4=
 go.uber.org/atomic v1.11.0 h1:ZvwS0R+56ePWxUNi+Atn9dWONBPp/AUETXlHW0DxSjE=
 go.uber.org/atomic v1.11.0/go.mod h1:LUxbIzbOniOlMKjJjyPfpl4v+PKK2cNJn91OQbhoJI0=
 go.yaml.in/yaml/v3 v3.0.4 h1:tfq32ie2Jv2UxXFdLJdh3jXuOzWiL1fo0bu/FbuKpbc=
@@ -57,6 +86,14 @@ golang.org/x/sys v0.41.0 h1:Ivj+2Cp/ylzLiEU89QhWblYnOE9zerudt9Ftecq2C6k=
 golang.org/x/sys v0.41.0/go.mod h1:OgkHotnGiDImocRcuBABYBEXf8A9a87e/uXjp9XT3ks=
 golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
 golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
+google.golang.org/genproto/googleapis/api v0.0.0-20260209200024-4cfbd4190f57 h1:JLQynH/LBHfCTSbDWl+py8C+Rg/k1OVH3xfcaiANuF0=
+google.golang.org/genproto/googleapis/api v0.0.0-20260209200024-4cfbd4190f57/go.mod h1:kSJwQxqmFXeo79zOmbrALdflXQeAYcUbgS7PbpMknCY=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57 h1:mWPCjDEyshlQYzBpMNHaEof6UX1PmHcaUODUywQ0uac=
+google.golang.org/genproto/googleapis/rpc v0.0.0-20260209200024-4cfbd4190f57/go.mod h1:j9x/tPzZkyxcgEFkiKEEGxfvyumM01BEtsW8xzOahRQ=
+google.golang.org/grpc v1.79.2 h1:fRMD94s2tITpyJGtBBn7MkMseNpOZU8ZxgC3MMBaXRU=
+google.golang.org/grpc v1.79.2/go.mod h1:KmT0Kjez+0dde/v2j9vzwoAScgEPx/Bw1CYChhHLrHQ=
+google.golang.org/protobuf v1.36.11 h1:fV6ZwhNocDyBLK0dj+fg8ektcVegBBuEolpbTQyBNVE=
+google.golang.org/protobuf v1.36.11/go.mod h1:HTf+CrKn2C3g5S8VImy6tdcUvCska2kB7j23XfzDpco=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20201130134442-10cb98267c6c h1:Hei/4ADfdWqJk1ZMxUNpqntNwaWcugrBjAiHlqqRiVk=

backend/internal/backend/server.go

@@ -33,6 +33,7 @@ import (
 	"github.com/libnovel/backend/internal/kokoro"
 	"github.com/libnovel/backend/internal/meili"
 	"github.com/libnovel/backend/internal/taskqueue"
+	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
 )
 
 // Dependencies holds all external services the backend server depends on.
@@ -170,9 +171,17 @@ func (s *Server) ListenAndServe(ctx context.Context) error {
 	mux.HandleFunc("POST /api/progress/{slug}", s.handleSetProgress)
 	mux.HandleFunc("DELETE /api/progress/{slug}", s.handleDeleteProgress)
 
+	// Wrap mux with OTel tracing (no-op when no TracerProvider is set),
+	// then with Sentry for panic recovery and error reporting.
+	var handler http.Handler = mux
+	handler = otelhttp.NewHandler(handler, "libnovel.backend",
+		otelhttp.WithMessageEvents(otelhttp.ReadEvents, otelhttp.WriteEvents),
+	)
+	handler = sentryhttp.New(sentryhttp.Options{Repanic: true}).Handle(handler)
+
 	srv := &http.Server{
 		Addr:         s.cfg.Addr,
-		Handler:      sentryhttp.New(sentryhttp.Options{Repanic: true}).Handle(mux),
+		Handler:      handler,
 		ReadTimeout:  15 * time.Second,
 		WriteTimeout: 60 * time.Second,
 		IdleTimeout:  60 * time.Second,

backend/internal/otelsetup/otelsetup.go

@@ -0,0 +1,74 @@
+// Package otelsetup initialises the OpenTelemetry SDK for the LibNovel backend.
+//
+// It reads two environment variables:
+//
+//	OTEL_EXPORTER_OTLP_ENDPOINT  — OTLP/HTTP endpoint, e.g. http://otel-collector:4318
+//	OTEL_SERVICE_NAME            — service name reported in traces (default: "backend")
+//
+// When OTEL_EXPORTER_OTLP_ENDPOINT is empty the function is a no-op and
+// returns a nil shutdown func, so the caller never needs to branch on it.
+//
+// Usage in main.go:
+//
+//	shutdown, err := otelsetup.Init(ctx, version)
+//	if err != nil { return err }
+//	if shutdown != nil { defer shutdown() }
+package otelsetup
+
+import (
+	"context"
+	"fmt"
+	"os"
+	"time"
+
+	"go.opentelemetry.io/otel"
+	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
+	"go.opentelemetry.io/otel/sdk/resource"
+	sdktrace "go.opentelemetry.io/otel/sdk/trace"
+	semconv "go.opentelemetry.io/otel/semconv/v1.26.0"
+)
+
+// Init sets up a TracerProvider that exports spans via OTLP/HTTP.
+// Returns a shutdown function (or nil if OTel is disabled) and any error.
+func Init(ctx context.Context, version string) (shutdown func(), err error) {
+	endpoint := os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT")
+	if endpoint == "" {
+		return nil, nil // OTel disabled — not an error
+	}
+
+	serviceName := os.Getenv("OTEL_SERVICE_NAME")
+	if serviceName == "" {
+		serviceName = "backend"
+	}
+
+	exp, err := otlptracehttp.New(ctx,
+		otlptracehttp.WithEndpoint(endpoint),
+		otlptracehttp.WithInsecure(), // collector is on the internal Docker network
+	)
+	if err != nil {
+		return nil, fmt.Errorf("otelsetup: create OTLP exporter: %w", err)
+	}
+
+	res, err := resource.New(ctx,
+		resource.WithAttributes(
+			semconv.ServiceName(serviceName),
+			semconv.ServiceVersion(version),
+		),
+	)
+	if err != nil {
+		return nil, fmt.Errorf("otelsetup: create resource: %w", err)
+	}
+
+	tp := sdktrace.NewTracerProvider(
+		sdktrace.WithBatcher(exp),
+		sdktrace.WithResource(res),
+		sdktrace.WithSampler(sdktrace.ParentBased(sdktrace.TraceIDRatioBased(0.2))),
+	)
+	otel.SetTracerProvider(tp)
+
+	return func() {
+		shutCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		_ = tp.Shutdown(shutCtx)
+	}, nil
+}

docker-compose.yml

@@ -161,6 +161,8 @@ services:
       KOKORO_URL: "${KOKORO_URL}"
       KOKORO_VOICE: "${KOKORO_VOICE}"
       GLITCHTIP_DSN: "${GLITCHTIP_DSN}"
+      OTEL_EXPORTER_OTLP_ENDPOINT: "${OTEL_EXPORTER_OTLP_ENDPOINT}"
+      OTEL_SERVICE_NAME: "backend"
     healthcheck:
       test: ["CMD", "/healthcheck", "http://localhost:8080/health"]
       interval: 15s
@@ -217,8 +219,9 @@ services:
       KOKORO_URL: "${KOKORO_URL}"
       KOKORO_VOICE: "${KOKORO_VOICE}"
       GLITCHTIP_DSN: "${GLITCHTIP_DSN}"
+      OTEL_EXPORTER_OTLP_ENDPOINT: "${OTEL_EXPORTER_OTLP_ENDPOINT}"
+      OTEL_SERVICE_NAME: "runner"
     healthcheck:
-      # The runner writes /tmp/runner.alive on every poll.
       # 120s = 2× the default 30s poll interval with generous headroom.
       test: ["CMD", "/healthcheck", "file", "/tmp/runner.alive", "120"]
       interval: 60s
@@ -267,6 +270,9 @@ services:
       PUBLIC_UMAMI_SCRIPT_URL: "${PUBLIC_UMAMI_SCRIPT_URL}"
       # GlitchTip client + server-side error tracking
       PUBLIC_GLITCHTIP_DSN: "${PUBLIC_GLITCHTIP_DSN}"
+      # OpenTelemetry tracing
+      OTEL_EXPORTER_OTLP_ENDPOINT: "${OTEL_EXPORTER_OTLP_ENDPOINT}"
+      OTEL_SERVICE_NAME: "ui"
       # OAuth2 providers
       GOOGLE_CLIENT_ID: "${GOOGLE_CLIENT_ID}"
       GOOGLE_CLIENT_SECRET: "${GOOGLE_CLIENT_SECRET}"

homelab/docker-compose.yml

@@ -72,9 +72,9 @@ services:
       LOG_LEVEL: "${LOG_LEVEL}"
       GLITCHTIP_DSN: "${GLITCHTIP_DSN}"
 
-      # OTel — send runner traces/metrics to the local collector
-      OTEL_EXPORTER_OTLP_ENDPOINT: "http://otel-collector:4317"
-      OTEL_SERVICE_NAME: "libnovel-runner"
+      # OTel — send runner traces/metrics to the local collector (HTTP)
+      OTEL_EXPORTER_OTLP_ENDPOINT: "http://otel-collector:4318"
+      OTEL_SERVICE_NAME: "runner"
 
     healthcheck:
       test: ["CMD", "/healthcheck", "file", "/tmp/runner.alive", "120"]

ui/package.json

@@ -30,6 +30,10 @@
 	"dependencies": {
 		"@aws-sdk/client-s3": "^3.1005.0",
 		"@aws-sdk/s3-request-presigner": "^3.1005.0",
+		"@opentelemetry/exporter-trace-otlp-http": "^0.214.0",
+		"@opentelemetry/resources": "^2.6.1",
+		"@opentelemetry/sdk-node": "^0.214.0",
+		"@opentelemetry/semantic-conventions": "^1.40.0",
 		"@sentry/sveltekit": "^10.45.0",
 		"cropperjs": "^1.6.2",
 		"ioredis": "^5.3.2",

ui/src/hooks.server.ts

@@ -7,6 +7,26 @@ import { env as pubEnv } from '$env/dynamic/public';
 import { log } from '$lib/server/logger';
 import { createUserSession, touchUserSession, isSessionRevoked } from '$lib/server/pocketbase';
 import { drain as drainPresignCache } from '$lib/server/presignCache';
+import { NodeSDK } from '@opentelemetry/sdk-node';
+import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-http';
+import { Resource } from '@opentelemetry/resources';
+import { ATTR_SERVICE_NAME, ATTR_SERVICE_VERSION } from '@opentelemetry/semantic-conventions';
+
+// ─── OpenTelemetry server-side tracing ────────────────────────────────────────
+// No-op when OTEL_EXPORTER_OTLP_ENDPOINT is unset (e.g. local dev).
+const otlpEndpoint = process.env.OTEL_EXPORTER_OTLP_ENDPOINT;
+if (otlpEndpoint) {
+	const sdk = new NodeSDK({
+		resource: new Resource({
+			[ATTR_SERVICE_NAME]: process.env.OTEL_SERVICE_NAME ?? 'ui',
+			[ATTR_SERVICE_VERSION]: pubEnv.PUBLIC_BUILD_VERSION ?? 'dev'
+		}),
+		traceExporter: new OTLPTraceExporter({ url: `${otlpEndpoint}/v1/traces` })
+	});
+	sdk.start();
+	process.once('SIGTERM', () => sdk.shutdown().catch(() => {}));
+	process.once('SIGINT', () => sdk.shutdown().catch(() => {}));
+}
 
 // ─── Sentry / GlitchTip server-side error tracking ────────────────────────────
 // No-op when PUBLIC_GLITCHTIP_DSN is unset (e.g. local dev).