feat(server/otel): integrate OpenTelemetry logging and emit logs with context

apps/server/package.json

@@ -24,6 +24,7 @@
     "@moeru/eventa": "catalog:",
     "@moeru/std": "catalog:",
     "@opentelemetry/api": "^1.9.1",
+    "@opentelemetry/api-logs": "^0.214.0",
     "@opentelemetry/exporter-logs-otlp-proto": "^0.214.0",
     "@opentelemetry/exporter-metrics-otlp-proto": "^0.214.0",
     "@opentelemetry/exporter-trace-otlp-proto": "^0.214.0",

apps/server/src/app.ts

@@ -16,7 +16,7 @@ import type { HonoEnv } from './types/hono'
 
 import process from 'node:process'
 
-import { initLogger, LoggerFormat, LoggerLevel, useLogger } from '@guiiai/logg'
+import { initLogger, LoggerFormat, LoggerLevel, setGlobalHookPostLog, useLogger } from '@guiiai/logg'
 import { serve } from '@hono/node-server'
 import { createNodeWebSocket } from '@hono/node-ws'
 import { Hono } from 'hono'
@@ -29,7 +29,7 @@ import { createAuth } from './libs/auth'
 import { createDrizzle, migrateDatabase } from './libs/db'
 import { parsedEnv } from './libs/env'
 import { initializeExternalDependency } from './libs/external-dependency'
-import { initOtel } from './libs/otel'
+import { emitOtelLog, initOtel } from './libs/otel'
 import { createRedis } from './libs/redis'
 import { sessionMiddleware } from './middlewares/auth'
 import { otelMiddleware } from './middlewares/otel'
@@ -190,6 +190,11 @@ export async function createApp() {
   injeca.setLogger(createLoggLogger(useLogger('injeca').useGlobalConfig()))
   const logger = useLogger('app').useGlobalConfig()
 
+  // Forward logg output to OpenTelemetry log exporter
+  setGlobalHookPostLog((log) => {
+    emitOtelLog(log.level, log.context, log.message, log.fields as Record<string, string | number | boolean>)
+  })
+
   const otel = injeca.provide('libs:otel', {
     dependsOn: { env: parsedEnv, lifecycle },
     build: ({ dependsOn }) => {

apps/server/src/libs/otel.ts

@@ -7,7 +7,8 @@ import type { Env } from './env'
 import { env as processEnv } from 'node:process'
 
 import { useLogger } from '@guiiai/logg'
-import { diag, DiagConsoleLogger, DiagLogLevel, metrics } from '@opentelemetry/api'
+import { diag, DiagConsoleLogger, DiagLogLevel, metrics, trace } from '@opentelemetry/api'
+import { logs, SeverityNumber } from '@opentelemetry/api-logs'
 import { OTLPLogExporter } from '@opentelemetry/exporter-logs-otlp-proto'
 import { OTLPMetricExporter } from '@opentelemetry/exporter-metrics-otlp-proto'
 import { OTLPTraceExporter } from '@opentelemetry/exporter-trace-otlp-proto'
@@ -298,3 +299,39 @@ export function initOtel(env: Env): OtelInstance | undefined {
     shutdown,
   }
 }
+
+const severityMap: Record<string, SeverityNumber> = {
+  debug: SeverityNumber.DEBUG,
+  verbose: SeverityNumber.TRACE,
+  log: SeverityNumber.INFO,
+  info: SeverityNumber.INFO,
+  warn: SeverityNumber.WARN,
+  error: SeverityNumber.ERROR,
+}
+
+/**
+ * Emit a log record to OpenTelemetry.
+ * Automatically attaches the active span's traceId/spanId when available.
+ */
+export function emitOtelLog(
+  level: string,
+  context: string,
+  message: string,
+  attributes?: Record<string, string | number | boolean>,
+): void {
+  const otelLogger = logs.getLogger(context)
+  const spanContext = trace.getActiveSpan()?.spanContext()
+
+  otelLogger.emit({
+    severityNumber: severityMap[level.toLowerCase()] ?? SeverityNumber.INFO,
+    severityText: level.toUpperCase(),
+    body: message,
+    attributes: {
+      ...attributes,
+      ...(spanContext && {
+        trace_id: spanContext.traceId,
+        span_id: spanContext.spanId,
+      }),
+    },
+  })
+}

pnpm-lock.yaml

@@ -530,6 +530,9 @@ importers:
       '@opentelemetry/api':
         specifier: ^1.9.1
         version: 1.9.1
+      '@opentelemetry/api-logs':
+        specifier: ^0.214.0
+        version: 0.214.0
       '@opentelemetry/exporter-logs-otlp-proto':
         specifier: ^0.214.0
         version: 0.214.0(@opentelemetry/api@1.9.1)