feat: Add open telemetry (#2318)

* feat: add OpenTelemetry tracing infrastructure

Introduce distributed tracing capabilities using OpenTelemetry:

- Add @opentelemetry packages to shared-server for tracing
- Create tracing utility module with span helpers (withSpan, addSpanEvent, etc.)
- Add tRPC middleware for automatic span creation on API calls
- Initialize tracing in API and workers entry points
- Add demo instrumentation to bookmark creation and crawler worker
- Add configuration options (OTEL_TRACING_ENABLED, OTEL_EXPORTER_OTLP_ENDPOINT, etc.)
- Document tracing configuration in environment variables docs

When enabled, traces are collected for tRPC calls, bookmark creation flow,
and crawler operations, with support for any OTLP-compatible backend (Jaeger, Tempo, etc.)

* refactor: remove tracing from workers for now

Keep tracing infrastructure but remove worker instrumentation:
- Remove tracing initialization from workers entry point
- Remove tracing instrumentation from crawler worker
- Fix formatting in tracing files

The tracing infrastructure remains available for future use.

* add hono and next tracing

* remove extra span logging

* more fixes

* update config

* some fixes

* upgrade packages

* remove unneeded packages

---------

Co-authored-by: Claude <noreply@anthropic.com>

2 files changed, 17 insertions, 1 deletions

diff --git a/packages/api/index.ts b/packages/api/index.ts
index 3df7b429..ac31c977 100644
--- a/packages/api/index.ts
+++ b/packages/api/index.ts
@@ -1,9 +1,11 @@
+import { httpInstrumentationMiddleware } from "@hono/otel";
 import { Hono } from "hono";
 import { cors } from "hono/cors";
 import { logger as loggerMiddleware } from "hono/logger";
 import { poweredBy } from "hono/powered-by";
 
 import { loadAllPlugins } from "@karakeep/shared-server";
+import serverConfig from "@karakeep/shared/config";
 import logger from "@karakeep/shared/logger";
 import { Context } from "@karakeep/trpc";
 
@@ -52,7 +54,20 @@ const app = new Hono<{
       logger.info(str);
     }),
   )
-  .use(poweredBy())
+  .use(poweredBy());
+
+// Add OpenTelemetry middleware if tracing is enabled
+if (serverConfig.tracing.enabled) {
+  app.use(
+    "*",
+    httpInstrumentationMiddleware({
+      serviceName: `${serverConfig.tracing.serviceName}-api`,
+      serviceVersion: serverConfig.serverVersion ?? "unknown",
+    }),
+  );
+}
+
+app
   .use(
     cors({
       origin: "*",
diff --git a/packages/api/package.json b/packages/api/package.json
index b5d90f03..e49204b9 100644
--- a/packages/api/package.json
+++ b/packages/api/package.json
@@ -13,6 +13,7 @@
     "test": "vitest"
   },
   "dependencies": {
+    "@hono/otel": "^1.1.0",
     "@hono/prometheus": "^1.0.2",
     "@hono/trpc-server": "^0.4.0",
     "@hono/zod-validator": "^0.5.0",