Jason Woltje
51e6ad0792
Implement comprehensive distributed tracing for HTTP requests and LLM operations using OpenTelemetry with GenAI semantic conventions. Features: - TelemetryService: SDK initialization with OTLP HTTP exporter - TelemetryInterceptor: Automatic HTTP request spans - @TraceLlmCall decorator: LLM operation tracing - GenAI semantic conventions for model/token tracking - Graceful degradation when tracing disabled Instrumented: - All HTTP requests (automatic spans) - OllamaProvider chat/chatStream/embed operations - Token counts, model names, durations Environment: - OTEL_ENABLED (default: true) - OTEL_SERVICE_NAME (default: mosaic-api) - OTEL_EXPORTER_OTLP_ENDPOINT (default: localhost:4318) Tests: 23 passing with full coverage Fixes #131 Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
101 lines
3.1 KiB
TypeScript
101 lines
3.1 KiB
TypeScript
import { Injectable, NestInterceptor, ExecutionContext, CallHandler, Logger } from "@nestjs/common";
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import { Observable, throwError } from "rxjs";
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import { tap, catchError } from "rxjs/operators";
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import type { Request, Response } from "express";
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import { TelemetryService } from "./telemetry.service";
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import type { Span } from "@opentelemetry/api";
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import { SpanKind } from "@opentelemetry/api";
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import {
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ATTR_HTTP_REQUEST_METHOD,
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ATTR_HTTP_RESPONSE_STATUS_CODE,
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ATTR_URL_FULL,
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ATTR_URL_PATH,
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} from "@opentelemetry/semantic-conventions";
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/**
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* Interceptor that automatically creates OpenTelemetry spans for all HTTP requests.
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* Records HTTP method, URL, status code, and trace context in response headers.
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*
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* @example
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* ```typescript
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* // Apply globally in AppModule
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* @Module({
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* providers: [
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* {
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* provide: APP_INTERCEPTOR,
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* useClass: TelemetryInterceptor,
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* },
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* ],
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* })
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* export class AppModule {}
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* ```
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*/
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@Injectable()
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export class TelemetryInterceptor implements NestInterceptor {
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private readonly logger = new Logger(TelemetryInterceptor.name);
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constructor(private readonly telemetryService: TelemetryService) {}
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/**
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* Intercept HTTP requests and wrap them in OpenTelemetry spans.
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*
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* @param context - The execution context
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* @param next - The next call handler
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* @returns Observable of the response with tracing applied
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*/
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intercept(context: ExecutionContext, next: CallHandler): Observable<unknown> {
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const httpContext = context.switchToHttp();
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const request = httpContext.getRequest<Request>();
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const response = httpContext.getResponse<Response>();
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const method = request.method;
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const path = request.path || request.url;
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const spanName = `${method} ${path}`;
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const span = this.telemetryService.startSpan(spanName, {
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kind: SpanKind.SERVER,
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attributes: {
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[ATTR_HTTP_REQUEST_METHOD]: method,
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[ATTR_URL_PATH]: path,
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[ATTR_URL_FULL]: request.url,
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"code.function": context.getHandler().name,
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"code.namespace": context.getClass().name,
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},
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});
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return next.handle().pipe(
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tap(() => {
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this.finalizeSpan(span, response);
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}),
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catchError((error: Error) => {
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this.telemetryService.recordException(span, error);
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this.finalizeSpan(span, response);
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return throwError(() => error);
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})
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);
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}
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/**
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* Finalize the span by setting status code and adding trace context to headers.
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*
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* @param span - The span to finalize
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* @param response - The HTTP response
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*/
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private finalizeSpan(span: Span, response: Response): void {
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try {
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const statusCode = response.statusCode;
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span.setAttribute(ATTR_HTTP_RESPONSE_STATUS_CODE, statusCode);
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// Add trace context to response headers for distributed tracing
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const spanContext = span.spanContext();
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if (spanContext.traceId) {
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response.setHeader("x-trace-id", spanContext.traceId);
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}
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} catch (error) {
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this.logger.warn("Failed to finalize span", error);
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} finally {
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span.end();
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}
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}
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}
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