Ruby heroku捆绑程序：未能加载命令：rackup

我正在尝试向heroku部署一个模块化的sinatra应用程序，它在本地运行良好。这在heroku日志中：

2020-12-28T21:05:15.907560+00:00 heroku[web.1]: Starting process with command `bundle exec rackup config.ru -p 58645`
2020-12-28T21:05:18.738254+00:00 app[web.1]: bundler: failed to load command: rackup (/app/vendor/bundle/ruby/2.7.0/bin/rackup)
2020-12-28T21:05:18.738283+00:00 app[web.1]: Gem::Exception: can't find executable rackup for gem rack. rack is not currently included in the bundle, perhaps you meant to add it to your Gemfile?

命令

bundle exec rackup config.ru-p 58645

在本地运行良好

这是我的config.ru

require_relative './config/environment.rb'
use EntreeController
use UserController
run ApplicationController

和环境.rb

APP_ENV = ENV["RACK_ENV"] || "development"
ENV['SINATRA_ENV'] ||= "development"

require 'require_all'
require 'bundler/setup'
Bundler.require(:default, ENV['SINATRA_ENV'])

require_all 'app'
require_all 'app/models'
require_all 'app/helpers'

和proc文件：

web: bundle exec rackup config.ru -p $PORT

---

如果有人碰到同样的问题，我会发布我的解决方案。我遵循了

Rakefile

上的指示：

一个解决方案是在部署到Heroku时完全删除Rakefile。另一种解决方案是仅将其放入Rakefile：

require "sinatra/activerecord"
require "sinatra/activerecord/rake"
require "./app" # or whereever your app is

---

切换到Bundler 2.1.4解决了我的问题

从长远来看，必须安装bundler 2.1.4并使用它，但为了测试，我只是在

Gemfile.lock

中手动编辑了该行：

BUNDLED WITH
   2.1.4

我使用的是Ruby 2.7.2和Bundler 2.2.8，Heroku buildpack提供了Bundler 2.1.4

有趣的是，Heroku对2.2.8一无所知