Request IDs

Every request handled by Bklar gets a unique ID. This ID is available on the context, returned in response headers, and useful for distributed tracing.

Default Behavior

Out of the box, Bklar generates a UUID v4 for each request and attaches it to ctx.requestId. The X-Request-Id header is automatically included in all responses.

app.get("/", (ctx) => {
  console.log(`Handling request ${ctx.requestId}`);
  return ctx.text("ok");
});

curl -i http://localhost:3000/
# HTTP/1.1 200 OK
# X-Request-Id: f47ac10b-58cc-4372-a567-0e02b2c3d479

Propagation

If the incoming request already has an X-Request-Id header, Bklar reuses it instead of generating a new one. This enables distributed tracing across services.

curl -H "X-Request-Id: trace-abc-123" http://localhost:3000/
# X-Request-Id: trace-abc-123

Custom Configuration

Use the requestId option to customize the header name or ID generator:

const app = Bklar({
  requestId: {
    headerName: "X-Correlation-Id",    // Custom header
    generator: () => `req-${Date.now()}`,  // Custom generator
  },
});