Middleware stack config ideas.

api-stack.js

/**
 * Module dependencies.
 */
var stack = require("simple-stack-common")
  , cors = require("connect-xcors");

/**
 * Expose the stack
 */
module.exports = exports = function(config) {
  if (!config) config = {};

  // Create a simple-stack-common app
  var pack = stack(config);

  pack
    .useAfter("base", cors)
    .use(require("./lib/not-found"))
    .use(require("./lib/error-handler"));  // the change is pack-n-stack would auto-apply config.errorHandler

  // Return the pack
  return pack;
};

/**
 * Expose connect.middleware as stack.*
 */
stack.middleware(exports);

api.js

/**
 * Module dependencies.
 */
var stack = require('./api-stack');

/**
 * Configure the api stack
 */
var config = {
  errorHandler: {
    message: ["<pre>", "</pre>"]
  }
};

/**
 * Expose the app
 */
var app = module.exports = stack(config);

configure-stack.js

/**
 * Module dependencies.
 */
var stack = require("simple-stack-common")
  , cors = require("connect-xcors")
  , notFound = require("./lib/not-found")
  , errorHandler = require("./lib/error-handler");

/**
 * Expose the stack
 */
module.exports = exports = function(config) {
  if (!config) config = {};

  function configure(fn) {
    return fn(config[fn.name]);
  }

  // Create a simple-stack-common app
  var pack = stack(config);

  pack
    .useAfter("base", configure(cors) )
    .use( configure(notFound) )
    .use( configure(errorHandler) );  // the change is pack-n-stack would auto-apply config.errorHandler

  // Return the pack
  return pack;
};

/**
 * Expose connect.middleware as stack.*
 */
stack.middleware(exports);

configure-stack2.js

/**
 * Module dependencies.
 */
var stack = require("simple-stack-common")
  , cors = require("connect-xcors")
  , notFound = require("./lib/not-found")
  , errorHandler = require("./lib/error-handler");

/**
 * Expose the stack
 */
module.exports = exports = function(config) {
  if (!config) config = {};

  // Create a simple-stack-common app
  var pack = stack(config);

  pack
    .useAfter("base", pack.configure(cors) )
    .use( pack.configure(notFound) )
    .use( pack.configure(errorHandler) );  // the change is pack-n-stack would auto-apply config.errorHandler

  // Return the pack
  return pack;
};

/**
 * Expose connect.middleware as stack.*
 */
stack.middleware(exports);

other-stack.js

/**
 * Module dependencies.
 */
var stack = require("simple-stack-common")
  , cors = require("connect-xcors")
  , notFound = require("./lib/not-found")
  , errorHandler = require("./lib/error-handler");

/**
 * Expose the stack
 */
module.exports = exports = function(config) {
  if (!config) config = {};

  // Create a simple-stack-common app
  var pack = stack(config);

  pack
    .useAfter("base", cors(config[cors.name]) )
    .use( notFound(config[notFound.name]) )
    .use( errorHandler(config[errorHandler.name]) );  // the change is pack-n-stack would auto-apply config.errorHandler

  // Return the pack
  return pack;
};

/**
 * Expose connect.middleware as stack.*
 */
stack.middleware(exports);