Function startServer

packages/runtime-core/src/server-starter.ts:33–99

(options: ServerOptions)

 * Spawns `python -m deepnote_toolkit server` and waits for it to be ready.
 */
export async function startServer(options: ServerOptions): Promise<ServerInfo> {
  const { pythonEnv, workingDirectory, port, startupTimeoutMs = SERVER_STARTUP_TIMEOUT_MS } = options

  // Resolve the Python executable from the venv path
  const pythonPath = await resolvePythonExecutable(pythonEnv)

  // Find available consecutive ports (Jupyter + LSP)
  const jupyterPort = await findConsecutiveAvailablePorts(port ?? DEFAULT_PORT)
  const lspPort = jupyterPort + 1

  // Set up environment with correct Python paths (PATH, VIRTUAL_ENV)
  const baseEnv: Record<string, string | undefined> = { ...process.env, ...options.env }
  const env = await buildPythonEnv(pythonPath, baseEnv)
  env.DEEPNOTE_RUNTIME__RUNNING_IN_DETACHED_MODE = 'true'
  env.DEEPNOTE_ENFORCE_PIP_CONSTRAINTS = 'true'

  // Spawn deepnote-toolkit server
  const serverProcess = spawn(
    pythonPath,
    ['-m', 'deepnote_toolkit', 'server', '--jupyter-port', String(jupyterPort), '--ls-port', String(lspPort)],
    {
      cwd: workingDirectory,
      env,
      stdio: ['ignore', 'pipe', 'pipe'],
    }
  )

  const serverInfo: ServerInfo = {
    url: `http://localhost:${jupyterPort}`,
    jupyterPort,
    lspPort,
    process: serverProcess,
  }

  // Collect output for error reporting
  let stdout = ''
  let stderr = ''

  serverProcess.stdout?.on('data', (data: Buffer) => {
    stdout += data.toString()
    // Keep last 5000 chars
    if (stdout.length > 5000) stdout = stdout.slice(-5000)
  })

  serverProcess.stderr?.on('data', (data: Buffer) => {
    stderr += data.toString()
    if (stderr.length > 5000) stderr = stderr.slice(-5000)
  })

  // Handle early process exit
  const exitPromise = new Promise<never>((_, reject) => {
    serverProcess.on('exit', (code, signal) => {
      reject(new Error(`Server process exited unexpectedly (code=${code}, signal=${signal}).\nstderr: ${stderr}`))
    })
  })

  // Wait for server to be ready
  try {