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Expose route rule in request metrics #18

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Merged
phaedrus-on-git merged 1 commit into from
Sep 26, 2026
Merged

Expose route rule in request metrics #18

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22 changes: 18 additions & 4 deletions internal/server/server.go
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Original file line number Diff line number Diff line change
Expand Up @@ -186,7 +186,7 @@ func (s *Server) proxyOpenAI(w http.ResponseWriter, r *http.Request) {
setBackendAuth(req, backend)
}
proxy.ModifyResponse = func(resp *http.Response) error {
instrumentBackendResponse(resp, started, waited, routedModel, backend, requestID, s.metrics)
instrumentBackendResponse(resp, started, waited, routedModel, backend, requestID, routeRule, s.metrics)
return nil
}
proxy.ErrorHandler = func(rw http.ResponseWriter, req *http.Request, proxyErr error) {
Expand All @@ -202,7 +202,9 @@ func (s *Server) proxyOpenAI(w http.ResponseWriter, r *http.Request) {
"duration_ms", time.Since(started).Milliseconds(),
"error", proxyErr,
)
s.metrics.record(requestMetricsFromModel(routedModel, backend, http.StatusBadGateway, started))
metrics := requestMetricsFromModel(routedModel, backend, http.StatusBadGateway, started)
metrics.RouteRule = routeRule
s.metrics.record(metrics)
writeOpenAIError(rw, http.StatusBadGateway, "backend request failed", "devrail_backend_error", "backend_request_failed")
}

Expand Down Expand Up @@ -341,6 +343,7 @@ type responseTelemetry struct {
TargetModel string
Backend string
UpstreamModel string
RouteRule string
Status int
Streaming bool
FirstEvent time.Time
Expand Down Expand Up @@ -460,6 +463,7 @@ func logTelemetry(telemetry *responseTelemetry) {
Alias: telemetry.Alias,
TargetModel: telemetry.TargetModel,
Backend: telemetry.Backend,
RouteRule: telemetry.RouteRule,
Status: telemetry.Status,
Streaming: telemetry.Streaming,
FirstEvent: telemetry.FirstEvent,
Expand Down Expand Up @@ -495,10 +499,13 @@ func instrumentBackendResponse(
model config.ModelConfig,
backend config.BackendConfig,
requestID string,
routeRule string,
metrics *metricsRegistry,
) {
if resp.Body == nil {
metrics.record(requestMetricsFromModel(model, backend, resp.StatusCode, started))
requestMetrics := requestMetricsFromModel(model, backend, resp.StatusCode, started)
requestMetrics.RouteRule = routeRule
metrics.record(requestMetrics)
return
}

Expand All @@ -507,6 +514,7 @@ func instrumentBackendResponse(
Alias: model.ID,
TargetModel: model.TargetModel,
Backend: backend.ID,
RouteRule: routeRule,
Status: resp.StatusCode,
Started: started,
QueueWait: queueWait,
Expand Down Expand Up @@ -574,6 +582,7 @@ type requestMetrics struct {
Alias string
TargetModel string
Backend string
RouteRule string
Status int
Streaming bool
FirstEvent time.Time
Expand Down Expand Up @@ -607,6 +616,7 @@ type metricLabels struct {
Alias string
Backend string
TargetModel string
RouteRule string
Status string
Streaming string
Le string
Expand Down Expand Up @@ -667,6 +677,7 @@ func (registry *metricsRegistry) record(metrics requestMetrics) {
Alias: metrics.Alias,
Backend: metrics.Backend,
TargetModel: metrics.TargetModel,
RouteRule: metrics.RouteRule,
Status: strconv.Itoa(metrics.Status),
Streaming: strconv.FormatBool(metrics.Streaming),
}
Expand Down Expand Up @@ -823,7 +834,7 @@ func sortedHistogramSeries(series map[string]*histogramSeries) []*histogramSerie
}

func (labels metricLabels) key() string {
return labels.Alias + "\xff" + labels.Backend + "\xff" + labels.TargetModel + "\xff" + labels.Status + "\xff" + labels.Streaming
return labels.Alias + "\xff" + labels.Backend + "\xff" + labels.TargetModel + "\xff" + labels.RouteRule + "\xff" + labels.Status + "\xff" + labels.Streaming
}

func (labels metricLabels) with(name, value string) metricLabels {
Expand All @@ -845,6 +856,9 @@ func (labels metricLabels) prometheus() string {
if labels.TargetModel != "" {
parts = append(parts, `target_model="`+escapePrometheusLabel(labels.TargetModel)+`"`)
}
if labels.RouteRule != "" {
parts = append(parts, `route_rule="`+escapePrometheusLabel(labels.RouteRule)+`"`)
}
if labels.Status != "" {
parts = append(parts, `status="`+escapePrometheusLabel(labels.Status)+`"`)
}
Expand Down
35 changes: 31 additions & 4 deletions internal/server/server_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -169,6 +169,15 @@ func TestRoutingRuleSelectsTargetByPromptSize(t *testing.T) {
if backendModel != "deep-model" {
t.Fatalf("unexpected backend model: %q", backendModel)
}

metricsReq := httptest.NewRequest(http.MethodGet, "/metrics", nil)
metricsRec := httptest.NewRecorder()
srv.ServeHTTP(metricsRec, metricsReq)
body := metricsRec.Body.String()
want := `devrail_router_requests_total{alias="local-coder-auto",backend="lmstudio",target_model="deep-model",route_rule="large-prompt",status="200",streaming="false"} 1`
if !strings.Contains(body, want) {
t.Fatalf("expected metrics to contain %s, got:\n%s", want, body)
}
}

func TestRoutingRuleFallsBackToDefaultTarget(t *testing.T) {
Expand Down Expand Up @@ -298,6 +307,15 @@ func TestRoutingClassifierSelectsTarget(t *testing.T) {
if backendModel != "deep-model" {
t.Fatalf("unexpected backend model: %q", backendModel)
}

metricsReq := httptest.NewRequest(http.MethodGet, "/metrics", nil)
metricsRec := httptest.NewRecorder()
srv.ServeHTTP(metricsRec, metricsReq)
body := metricsRec.Body.String()
want := `devrail_router_requests_total{alias="local-coder-auto",backend="lmstudio",target_model="deep-model",route_rule="classifier",status="200",streaming="false"} 1`
if !strings.Contains(body, want) {
t.Fatalf("expected metrics to contain %s, got:\n%s", want, body)
}
}

func TestRoutingClassifierFallsBackToDefaultTarget(t *testing.T) {
Expand Down Expand Up @@ -449,6 +467,15 @@ func TestRoutingPreclassifierSelectsTargetBeforeClassifier(t *testing.T) {
if backendModel != "deep-model" {
t.Fatalf("unexpected backend model: %q", backendModel)
}

metricsReq := httptest.NewRequest(http.MethodGet, "/metrics", nil)
metricsRec := httptest.NewRecorder()
srv.ServeHTTP(metricsRec, metricsReq)
body := metricsRec.Body.String()
want := `devrail_router_requests_total{alias="local-coder-auto",backend="lmstudio",target_model="deep-model",route_rule="preclassifier",status="200",streaming="false"} 1`
if !strings.Contains(body, want) {
t.Fatalf("expected metrics to contain %s, got:\n%s", want, body)
}
}

func TestRoutingPreclassifierFallsThroughForNegatedKeyword(t *testing.T) {
Expand Down Expand Up @@ -981,8 +1008,8 @@ func TestMetricsEndpointExposesRequestTelemetry(t *testing.T) {
body := rec.Body.String()
for _, want := range []string{
"# TYPE devrail_router_requests_total counter",
`devrail_router_requests_total{alias="local-coder",backend="lmstudio",target_model="target-model",status="200",streaming="false"} 1`,
`devrail_router_request_duration_seconds_bucket{alias="local-coder",backend="lmstudio",target_model="target-model",status="200",streaming="false",le="+Inf"} 1`,
`devrail_router_requests_total{alias="local-coder",backend="lmstudio",target_model="target-model",route_rule="default",status="200",streaming="false"} 1`,
`devrail_router_request_duration_seconds_bucket{alias="local-coder",backend="lmstudio",target_model="target-model",route_rule="default",status="200",streaming="false",le="+Inf"} 1`,
"devrail_router_prompt_tokens_total 9",
"devrail_router_completion_tokens_total 3",
"devrail_router_total_tokens_total 12",
Expand Down Expand Up @@ -1019,8 +1046,8 @@ func TestMetricsEndpointExposesStreamingFirstEventLatency(t *testing.T) {
body := metricsRec.Body.String()

for _, want := range []string{
`devrail_router_requests_total{alias="local-coder",backend="lmstudio",target_model="target-model",status="200",streaming="true"} 1`,
`devrail_router_first_event_latency_seconds_bucket{alias="local-coder",backend="lmstudio",target_model="target-model",status="200",streaming="true",le="+Inf"} 1`,
`devrail_router_requests_total{alias="local-coder",backend="lmstudio",target_model="target-model",route_rule="default",status="200",streaming="true"} 1`,
`devrail_router_first_event_latency_seconds_bucket{alias="local-coder",backend="lmstudio",target_model="target-model",route_rule="default",status="200",streaming="true",le="+Inf"} 1`,
} {
if !strings.Contains(body, want) {
t.Fatalf("expected metrics to contain %s, got:\n%s", want, body)
Expand Down
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