Function startDevServer

packages/python/src/start-dev-server.ts:590–950

}

export const startDevServer: StartDevServer = async opts => {
  const {
    entrypoint: rawEntrypoint,
    workPath,
    meta = {},
    config,
    service,
    onStdout,
    onStderr,
  } = opts;

  const framework = config?.framework;

  // Check for an existing persistent server.
  // Include serviceName so that services sharing a workspace get separate servers.
  const serviceName =
    service?.name ??
    (typeof meta.serviceName === 'string' ? meta.serviceName : undefined);
  const serverKey = serviceName
    ? `${workPath}::${framework}::${serviceName}`
    : `${workPath}::${framework}`;
  const existing = PERSISTENT_SERVERS.get(serverKey);
  if (existing) {
    return {
      port: existing.port,
      pid: existing.pid,
      shutdown: async () => {
        // no-op so CLI does not kill persistent server per request
      },
    };
  }

  // Check for a pending start operation before spawning a new server
  {
    const pending = PENDING_STARTS.get(serverKey);
    if (pending) {
      const { port, pid } = await pending;
      return {
        port,
        pid,
        shutdown: async () => {},
      };
    }
  }

  // No framework is defined, so most likely this is 'handler' class-based
  // serverless functions that should be served directly using vercel-runtime
  // instead of dev server.
  // Otherwise the framework would be a known one or just 'python'.
  if (!framework) {
    return null;
  }

  // Silence Node warnings and install cleanup handlers once
  if (!restoreWarnings) restoreWarnings = silenceNodeWarnings();
  installGlobalCleanupHandlers();
  const env = { ...process.env, ...(meta.env || {}) } as NodeJS.ProcessEnv;
  const entrypoint = rawEntrypoint === '<detect>' ? undefined : rawEntrypoint;