HTTP Middleware

The @deeptracer/node package includes middleware for Hono and Express that automatically creates a span for every incoming HTTP request.

Hono

import { Hono } from "hono"
import { createLogger, honoMiddleware } from "@deeptracer/node"

const logger = createLogger({
  apiKey: process.env.DEEPTRACER_KEY,
  endpoint: process.env.DEEPTRACER_ENDPOINT,
  service: "api",
})

const app = new Hono()
app.use(honoMiddleware(logger))

app.get("/users", (c) => {
  return c.json({ users: [] })
})
// → creates a span: "GET /users"

Express

import express from "express"
import { createLogger, expressMiddleware } from "@deeptracer/node"

const logger = createLogger({
  apiKey: process.env.DEEPTRACER_KEY,
  endpoint: process.env.DEEPTRACER_ENDPOINT,
  service: "api",
})

const app = express()
app.use(expressMiddleware(logger))

app.get("/users", (req, res) => {
  res.json({ users: [] })
})
// → creates a span: "GET /users"

What the middleware does

For each incoming request, the middleware:

Creates a request-scoped logger with forRequest(request) to extract incoming trace context from headers
Starts a span named "{METHOD} {path}" (e.g., "GET /users")
Sets x-trace-id and x-span-id response headers so the caller can correlate
Ends the span when the response finishes, marking it "ok" or "error" based on status code

Options

Both honoMiddleware() and expressMiddleware() accept an optional second argument:

app.use(honoMiddleware(logger, {
  operationName: (method, path) => `${method} ${path}`,
  ignorePaths: ["/health", "/ready", "/.well-known"],
}))

Option	Type	Default	Description
`operationName`	`(method, path) => string`	`"{METHOD} {path}"`	Custom span name for each request.
`ignorePaths`	`string[]`	`[]`	Paths to skip tracing entirely. Matched with `startsWith`.

Ignoring health checks

Health check endpoints can generate a lot of noise. Exclude them:

app.use(expressMiddleware(logger, {
  ignorePaths: ["/health", "/ready", "/ping"],
}))

Custom operation names

Group dynamic routes into a single operation:

app.use(honoMiddleware(logger, {
  operationName: (method, path) => {
    // /users/123 → "GET /users/:id"
    const normalized = path.replace(/\/[a-f0-9-]{20,}/g, "/:id")
    return `${method} ${normalized}`
  },
}))

Next.js

You don't need middleware for Next.js. The @deeptracer/nextjs package handles request tracing automatically via its OpenTelemetry integration. See Distributed Tracing for details.