Bun en production : ce qui marche, ce qui ne marche pas et ce qui m'a surpris | Akousa

bash

# Check your Bun version
bun --version
 
# Run a TypeScript file directly — no tsconfig, no compilation step
bun run server.ts
 
# Install packages
bun install
 
# Run tests
bun test
 
# Bundle for production
bun build ./src/index.ts --outdir ./dist

bash

# Clean install benchmark — delete node_modules and lockfile first
rm -rf node_modules bun.lockb package-lock.json
 
# Time npm
time npm install
# Real: ~18.4s (typical medium-sized project)
 
# Time bun
time bun install
# Real: ~2.1s

bash

# Quick and dirty benchmark with bombardier
# Testing a simple "Hello World" response
 
# Bun server
bombardier -c 100 -d 10s http://localhost:3000
# Requests/sec: ~105,000
 
# Node.js (native http module)
bombardier -c 100 -d 10s http://localhost:3001
# Requests/sec: ~48,000
 
# Node.js (Express)
bombardier -c 100 -d 10s http://localhost:3002
# Requests/sec: ~15,000

typescript

// fibonacci.ts — this is engine-bound, not runtime-bound
function fib(n: number): number {
  if (n <= 1) return n;
  return fib(n - 1) + fib(n - 2);
}
 
const start = performance.now();
console.log(fib(42));
console.log(`${(performance.now() - start).toFixed(0)}ms`);

bash

# Install hyperfine for proper benchmarking
brew install hyperfine  # macOS
# or: cargo install hyperfine
 
# Benchmark startup + execution of your actual app
hyperfine --warmup 3 \
  'node dist/server.js' \
  'bun src/server.ts' \
  --prepare 'sleep 0.1'
 
# For HTTP servers, use bombardier or wrk
# Important: test with realistic payloads, not "Hello World"
bombardier -c 50 -d 30s -l http://localhost:3000/api/users
 
# Memory comparison
/usr/bin/time -v node server.js  # Linux
/usr/bin/time -l bun server.ts   # macOS

bash

# Install all dependencies from package.json
bun install
 
# Add a dependency
bun add express
 
# Add a dev dependency
bun add -d vitest
 
# Remove a dependency
bun remove express
 
# Update a dependency
bun update express
 
# Install a specific version
bun add express@4.18.2

bash

# Install dependencies for all workspaces
bun install
 
# Run a script in a specific workspace
bun run --filter packages/shared build
 
# Add a dependency to a specific workspace
bun add react --filter apps/web

bash

# Step 1: Delete existing lockfile and node_modules
rm -rf node_modules package-lock.json yarn.lock pnpm-lock.yaml
 
# Step 2: Install with Bun
bun install
 
# Step 3: Verify your app still works
bun run dev
# or: node dist/server.js  (Bun package manager, Node runtime)

typescript

// These all work as expected in Bun
import fs from "node:fs";
import path from "node:path";
import crypto from "node:crypto";
import { Buffer } from "node:buffer";
import { EventEmitter } from "node:events";
import { Readable, Writable } from "node:stream";
import http from "node:http";
import https from "node:https";
import { URL, URLSearchParams } from "node:url";
import os from "node:os";
import child_process from "node:child_process";

typescript

// This will NOT work in Bun — V8-specific
const v8 = require("v8");
v8.serialize({ data: "test" });
 
// This WILL work — use Bun's equivalent or a cross-runtime approach
const encoded = new TextEncoder().encode(JSON.stringify({ data: "test" }));

typescript

const server = Bun.serve({
  port: 3000,
  fetch(req) {
    const url = new URL(req.url);
 
    if (url.pathname === "/") {
      return new Response("Hello from Bun!", {
        headers: { "Content-Type": "text/plain" },
      });
    }
 
    if (url.pathname === "/api/users") {
      const users = [
        { id: 1, name: "Alice" },
        { id: 2, name: "Bob" },
      ];
      return Response.json(users);
    }
 
    return new Response("Not Found", { status: 404 });
  },
});
 
console.log(`Server running at http://localhost:${server.port}`);

typescript

import { Database } from "bun:sqlite";
 
const db = new Database("app.db");
db.run(`
  CREATE TABLE IF NOT EXISTS todos (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    title TEXT NOT NULL,
    completed INTEGER DEFAULT 0,
    created_at TEXT DEFAULT (datetime('now'))
  )
`);
 
const server = Bun.serve({
  port: process.env.PORT || 3000,
 
  async fetch(req) {
    const url = new URL(req.url);
    const method = req.method;
 
    try {
      // GET /api/todos
      if (url.pathname === "/api/todos" && method === "GET") {
        const todos = db.query("SELECT * FROM todos ORDER BY created_at DESC").all();
        return Response.json(todos);
      }
 
      // POST /api/todos
      if (url.pathname === "/api/todos" && method === "POST") {
        const body = await req.json();
 
        if (!body.title || typeof body.title !== "string") {
          return Response.json({ error: "Title is required" }, { status: 400 });
        }
 
        const stmt = db.prepare("INSERT INTO todos (title) VALUES (?) RETURNING *");
        const todo = stmt.get(body.title);
        return Response.json(todo, { status: 201 });
      }
 
      // DELETE /api/todos/:id
      const deleteMatch = url.pathname.match(/^\/api\/todos\/(\d+)$/);
      if (deleteMatch && method === "DELETE") {
        const id = parseInt(deleteMatch[1], 10);
        db.run("DELETE FROM todos WHERE id = ?", [id]);
        return new Response(null, { status: 204 });
      }
 
      return Response.json({ error: "Not found" }, { status: 404 });
    } catch (error) {
      console.error("Request error:", error);
      return Response.json({ error: "Internal server error" }, { status: 500 });
    }
  },
});
 
console.log(`Server running on port ${server.port}`);

typescript

// Reading files
const file = Bun.file("./config.json");
const text = await file.text(); // Read as string
const json = await file.json(); // Parse as JSON directly
const bytes = await file.arrayBuffer(); // Read as ArrayBuffer
const stream = file.stream(); // Read as ReadableStream
 
// File metadata
console.log(file.size); // Size in bytes
console.log(file.type); // MIME type (e.g., "application/json")
 
// Writing files
await Bun.write("./output.txt", "Hello, World!");
await Bun.write("./data.json", JSON.stringify({ key: "value" }));
await Bun.write("./copy.png", Bun.file("./original.png"));
 
// Write a Response body to a file
const response = await fetch("https://example.com/data.json");
await Bun.write("./downloaded.json", response);

typescript

const server = Bun.serve({
  port: 3000,
 
  fetch(req, server) {
    const url = new URL(req.url);
 
    if (url.pathname === "/ws") {
      const upgraded = server.upgrade(req, {
        data: {
          userId: url.searchParams.get("userId"),
          joinedAt: Date.now(),
        },
      });
 
      if (!upgraded) {
        return new Response("WebSocket upgrade failed", { status: 400 });
      }
      return undefined;
    }
 
    return new Response("Use /ws for WebSocket connections");
  },
 
  websocket: {
    open(ws) {
      console.log(`Client connected: ${ws.data.userId}`);
      ws.subscribe("chat");
    },
 
    message(ws, message) {
      // Broadcast to all subscribers
      server.publish("chat", `${ws.data.userId}: ${message}`);
    },
 
    close(ws) {
      console.log(`Client disconnected: ${ws.data.userId}`);
      ws.unsubscribe("chat");
    },
  },
});

typescript

import { Database } from "bun:sqlite";
 
// Open or create a database
const db = new Database("myapp.db");
 
// WAL mode for better concurrent read performance
db.exec("PRAGMA journal_mode = WAL");
 
// Create tables
db.run(`
  CREATE TABLE IF NOT EXISTS users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    email TEXT UNIQUE NOT NULL,
    name TEXT NOT NULL,
    created_at TEXT DEFAULT (datetime('now'))
  )
`);
 
// Prepared statements (reusable, faster for repeated queries)
const insertUser = db.prepare("INSERT INTO users (email, name) VALUES ($email, $name) RETURNING *");
 
const findByEmail = db.prepare("SELECT * FROM users WHERE email = $email");
 
// Usage
const user = insertUser.get({
  $email: "alice@example.com",
  $name: "Alice",
});
console.log(user); // { id: 1, email: "alice@example.com", name: "Alice", ... }
 
// Transactions
const insertMany = db.transaction((users: { email: string; name: string }[]) => {
  for (const user of users) {
    insertUser.run({ $email: user.email, $name: user.name });
  }
  return users.length;
});
 
const count = insertMany([
  { email: "bob@example.com", name: "Bob" },
  { email: "carol@example.com", name: "Carol" },
]);
console.log(`Inserted ${count} users`);

typescript

// math.test.ts
import { describe, it, expect } from "bun:test";
 
describe("math utilities", () => {
  it("adds numbers correctly", () => {
    expect(1 + 2).toBe(3);
  });
 
  it("handles floating point", () => {
    expect(0.1 + 0.2).toBeCloseTo(0.3);
  });
});

bash

# Run all tests
bun test
 
# Run specific file
bun test math.test.ts
 
# Run tests matching a pattern
bun test --test-name-pattern "adds numbers"
 
# Watch mode
bun test --watch
 
# Coverage
bun test --coverage

typescript

import { describe, it, expect, mock, spyOn } from "bun:test";
import { fetchUsers } from "./api";
 
// Mock a module
mock.module("./database", () => ({
  query: mock(() => [{ id: 1, name: "Alice" }]),
}));
 
describe("fetchUsers", () => {
  it("returns users from database", async () => {
    const users = await fetchUsers();
    expect(users).toHaveLength(1);
    expect(users[0].name).toBe("Alice");
  });
});
 
// Spy on an object method
describe("console", () => {
  it("tracks console.log calls", () => {
    const logSpy = spyOn(console, "log");
    console.log("test message");
    expect(logSpy).toHaveBeenCalledWith("test message");
    logSpy.mockRestore();
  });
});

bash

# Bundle a single entry point
bun build ./src/index.ts --outdir ./dist
 
# Bundle for different targets
bun build ./src/index.ts --outdir ./dist --target browser
bun build ./src/index.ts --outdir ./dist --target bun
bun build ./src/index.ts --outdir ./dist --target node
 
# Minify
bun build ./src/index.ts --outdir ./dist --minify
 
# Generate sourcemaps
bun build ./src/index.ts --outdir ./dist --sourcemap external

typescript

const result = await Bun.build({
  entrypoints: ["./src/index.ts", "./src/worker.ts"],
  outdir: "./dist",
  target: "browser",
  minify: {
    whitespace: true,
    identifiers: true,
    syntax: true,
  },
  splitting: true, // Code splitting
  sourcemap: "external",
  external: ["react", "react-dom"], // Don't bundle these
  naming: "[dir]/[name]-[hash].[ext]",
  define: {
    "process.env.NODE_ENV": JSON.stringify("production"),
  },
});
 
if (!result.success) {
  console.error("Build failed:");
  for (const log of result.logs) {
    console.error(log);
  }
  process.exit(1);
}
 
for (const output of result.outputs) {
  console.log(`${output.path} — ${output.size} bytes`);
}

typescript

// utils.ts
export function used() {
  return "I'll be in the bundle";
}
 
export function unused() {
  return "I'll be tree-shaken away";
}
 
// index.ts
import { used } from "./utils";
console.log(used());

typescript

// build-info.ts — this file runs at BUILD TIME, not runtime
export function getBuildInfo() {
  return {
    builtAt: new Date().toISOString(),
    gitSha: require("child_process").execSync("git rev-parse --short HEAD").toString().trim(),
    nodeVersion: process.version,
  };
}

typescript

// app.ts
import { getBuildInfo } from "./build-info" with { type: "macro" };
 
// getBuildInfo() executes at bundle time
// The result is inlined as a static value
const info = getBuildInfo();
console.log(`Built at ${info.builtAt}, commit ${info.gitSha}`);

dockerfile

FROM oven/bun:1 AS base
WORKDIR /app
 
# Install dependencies
FROM base AS deps
COPY package.json bun.lockb ./
RUN bun install --frozen-lockfile --production
 
# Build (if needed)
FROM base AS build
COPY package.json bun.lockb ./
RUN bun install --frozen-lockfile
COPY . .
RUN bun run build
 
# Production
FROM base AS production
WORKDIR /app
 
# Don't run as root
RUN addgroup --system --gid 1001 appgroup && \
    adduser --system --uid 1001 appuser
USER appuser
 
COPY --from=deps /app/node_modules ./node_modules
COPY --from=build /app/dist ./dist
COPY --from=build /app/package.json ./
 
EXPOSE 3000
CMD ["bun", "run", "dist/server.js"]

dockerfile

# Build stage: full Bun image with all dependencies
FROM oven/bun:1 AS builder
WORKDIR /app
COPY package.json bun.lockb ./
RUN bun install --frozen-lockfile
COPY . .
RUN bun build ./src/index.ts --target bun --outdir ./dist --minify
 
# Runtime stage: smaller base image
FROM oven/bun:1-slim AS runtime
WORKDIR /app
 
RUN addgroup --system --gid 1001 appgroup && \
    adduser --system --uid 1001 appuser
USER appuser
 
COPY --from=builder /app/dist ./dist
 
EXPOSE 3000
CMD ["bun", "run", "dist/index.js"]

dockerfile

# Ultra-minimal Docker image using compiled binary
FROM oven/bun:1 AS builder
WORKDIR /app
COPY package.json bun.lockb ./
RUN bun install --frozen-lockfile
COPY . .
RUN bun build --compile ./src/server.ts --outfile server
 
# Final image — just the binary
FROM debian:bookworm-slim
WORKDIR /app
 
RUN addgroup --system --gid 1001 appgroup && \
    adduser --system --uid 1001 appuser
USER appuser
 
COPY --from=builder /app/server ./server
 
EXPOSE 3000
CMD ["./server"]

bash

# Node.js image
docker images | grep node
# node:20-slim    ~180MB
 
# Bun image
docker images | grep bun
# oven/bun:1-slim  ~130MB
 
# Compiled binary on debian:bookworm-slim
# ~80MB base + ~70MB binary = ~150MB total
 
# vs. Alpine with Node.js
# node:20-alpine   ~130MB + node_modules

json

{
  "version": "0.2.0",
  "configurations": [
    {
      "type": "bun",
      "request": "launch",
      "name": "Debug Bun",
      "program": "${workspaceFolder}/src/server.ts",
      "cwd": "${workspaceFolder}",
      "stopOnEntry": false,
      "watchMode": false
    }
  ]
}

bash

# Compare dependency counts
# A typical Express + SQLite + WebSocket project:
npm ls --all | wc -l
# ~340 packages
 
# The same functionality with Bun built-ins:
bun pm ls --all | wc -l
# ~12 packages (just your application code)

typescript

// Use Bun.serve() options for production tuning
Bun.serve({
  port: 3000,
 
  // Increase max request body size (default is 128MB)
  maxRequestBodySize: 1024 * 1024 * 50, // 50MB
 
  // Enable development mode for better error pages
  development: process.env.NODE_ENV !== "production",
 
  // Reuse port (useful for zero-downtime restarts)
  reusePort: true,
 
  fetch(req) {
    return new Response("OK");
  },
});

typescript

// Use Bun.Transpiler for runtime code transformation
const transpiler = new Bun.Transpiler({
  loader: "tsx",
  target: "browser",
});
 
const code = transpiler.transformSync(`
  const App: React.FC = () => <div>Hello</div>;
  export default App;
`);

typescript

// Node.js 18+ fetch and Bun's fetch are slightly different
// in how they handle certain headers and redirects
 
// Bun follows redirects by default (like browsers)
// Node.js fetch also follows redirects, but the behavior
// with certain status codes (303, 307, 308) can differ
 
const response = await fetch("https://api.example.com/data", {
  redirect: "manual", // Be explicit about redirect handling
});

typescript

// Bun exits when the event loop is empty
// Node.js sometimes keeps running due to lingering handles
 
// If your Bun script exits unexpectedly, something isn't
// keeping the event loop alive
 
// This will exit immediately in Bun:
setTimeout(() => {}, 0);
 
// This will keep running:
setTimeout(() => {}, 1000);
// (Bun exits after the timeout fires)

typescript

// Bun has its own tsconfig defaults
// If you're sharing a project between Bun and Node.js,
// be explicit in your tsconfig.json:
{
  "compilerOptions": {
    "target": "ESNext",
    "module": "ESNext",
    "moduleResolution": "bundler",
    "types": ["bun-types"]  // Add Bun type definitions
  }
}

bash

# Bun has built-in watch mode
bun --watch run server.ts
 
# This restarts the process on file changes
# It's not HMR (Hot Module Replacement) — it's a full restart
# But because Bun starts so fast, it feels instant

toml

# bunfig.toml — Bun's config file (optional)
 
[install]
# Use a private registry
registry = "https://npm.mycompany.com"
 
# Scoped registries
[install.scopes]
"@mycompany" = "https://npm.mycompany.com"
 
[test]
# Test configuration
coverage = true
coverageReporter = ["text", "lcov"]
 
[run]
# Shell to use for bun run
shell = "bash"

Ce qu'est réellement Bun

Les revendications de vitesse — benchmarks honnêtes

Temps de démarrage

Installation de paquets

Débit du serveur HTTP

Là où la différence est négligeable

Comment faire vos propres benchmarks

Bun comme gestionnaire de paquets

Les bases

La situation du fichier de verrouillage

Support des workspaces

Compatibilité avec les projets existants

Compatibilité Node.js

Ce qui marche

Ce qui ne marche pas (ou a des problèmes)

Le suivi de compatibilité

Les API intégrées de Bun

Bun.serve() — le serveur HTTP intégré

Bun.file() et Bun.write() — E/S fichier

Support WebSocket intégré

SQLite intégré avec bun:sqlite

Lanceur de tests Bun

Utilisation de base

Mocking

Bun Test vs. Vitest — ma comparaison honnête

Bundler Bun

Bundling de base

API programmatique

Tree-Shaking

Où Bun Build est insuffisant

Macros Bun

Utiliser Bun avec Next.js

Ce qui marche aujourd'hui

Ce qui est encore expérimental

Ma recommandation pour Next.js

Docker avec Bun

Dockerfile de base

Build multi-étapes pour une image minimale

Compilation en un seul binaire

Comparaison de taille

Patterns de migration

Phase 1 : gestionnaire de paquets uniquement (zéro risque)

Phase 2 : scripts et outillage

Phase 3 : lanceur de tests (risque moyen)

Phase 4 : runtime pour les nouveaux services (risque calculé)

Phase 5 : migration du runtime (avancé)

Variables d'environnement et configuration

Gestion des erreurs et débogage

Considérations de sécurité

Optimisation des performances

Pièges courants

1. Le comportement du Fetch global diffère

2. Comportement de sortie du processus

3. Configuration TypeScript

4. Hot Reload en développement

5. Le fichier de configuration bunfig.toml

Mon verdict

Où j'utilise Bun aujourd'hui

Où je reste avec Node.js

Ce que je surveille

Pour conclure

Articles similaires

Regex Cheat Sheet 2026 — Regular Expressions Made Simple

How to Compress Images Without Losing Quality: The Complete 2026 Guide

5. Le fichier de configuration `bunfig.toml`