部署Ruby on Rails到Heroku时遇NoMethodError错误求助

我是一名JavaScript开发者，正在学习Ruby on Rails。部署项目到Heroku时遇到NoMethodError: undefined method []' for nil:NilClass错误，怀疑是master.key的问题，试过重新创建项目、更换新的master.key并重构所有代码，但错误依旧存在。

错误栈信息 #

rails aborted!
NoMethodError: undefined method `[]' for nil:NilClass
/app/config/environments/production.rb:124:in `block in <main>'
...
`perform'
/app/vendor/bundle/ruby/3.0.0/gems/railties-6.1.5/lib/rails/command.rb:50:in `invoke'
/app/vendor/bundle/ruby/3.0.0/gems/railties-6.1.5/lib/rails/commands.rb:18:in `<main>'
/app/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
/app/vendor/bundle/ruby/3.0.0/gems/bootsnap-1.11.1/lib/bootsnap/load_path_cache/core_ext/kernel_require.rb:30:in `require'
Tasks: TOP => db:migrate => db:load_config => environment
(See full trace by running task with --trace)

production.rb代码片段 #

require 'active_support/core_ext/integer/time'

# rubocop: disable Metrics/BlockLength
Rails.application.configure do
  config.cache_classes = true
  config.eager_load = true

  # Full error reports are disabled and caching is turned on.
  config.consider_all_requests_local = false
  config.public_file_server.enabled = ENV['RAILS_SERVE_STATIC_FILES'].present?

  config.active_storage.service = :local

  config.log_level = :info

  # Prepend all log lines with the following tags.
  config.log_tags = [:request_id]

  config.action_mailer.perform_caching = false

  config.i18n.fallbacks = true

  # Send deprecation notices to registered listeners.
  config.active_support.deprecation = :notify

  # Log disallowed deprecations.
  config.active_support.disallowed_deprecation = :log

  # Tell Active Support which deprecation messages to disallow.
  config.active_support.disallowed_deprecation_warnings = []

  config.log_formatter = ::Logger::Formatter.new


  if ENV['RAILS_LOG_TO_STDOUT'].present?
    logger           = ActiveSupport::Logger.new(STDOUT)
    logger.formatter = config.log_formatter
    config.logger    = ActiveSupport::TaggedLogging.new(logger)
  end

  config.active_record.dump_schema_after_migration = false


  # Email
  config.action_mailer.default_url_options = {
    host: 'https://max-api-on-rails.herokuapp.com/'
  }
  config.action_mailer.delivery_method = :smtp
  config.action_mailer.smtp_settings = {
    address: "smtp.gmail.com",
    port: 587,
    domain:'gmail.com',
    user_name: Rails.application.credentials.zoho[:user_name],
    password: Rails.application.credentials.zoho[:password],
    authentication: 'login',
    ssl: true,
    tls: true,
    enable_starttls_auto: true
  }
end

问题定位 #

从错误栈和代码对应来看，报错行是production.rb的第124行，对应Rails.application.credentials.zoho[:user_name]或Rails.application.credentials.zoho[:password]——这说明Rails.application.credentials.zoho是nil，也就是Heroku环境中没有正确加载到zoho相关的凭据。

解决步骤 #

• 确认本地凭据配置
  本地执行rails credentials:edit，检查config/credentials.yml.enc中是否存在格式正确的zoho节点：

  zoho:
    user_name: your_actual_username
    password: your_actual_password
  

  确保保存后，本地master.key能正常解密该文件。

• 配置Heroku环境的凭据
  有两种方式可选：

  1. 设置RAILS_MASTER_KEY环境变量
     复制本地config/master.key的内容，在终端执行：

     heroku config:set RAILS_MASTER_KEY=你的master.key字符串
     

  2. 单独设置Zoho凭据的环境变量
     如果不想依赖master.key，直接在Heroku配置单独的变量：

     heroku config:set ZOHO_USER_NAME=你的Zoho用户名
     heroku config:set ZOHO_PASSWORD=你的Zoho密码
     

     同时修改production.rb中的SMTP配置：

     user_name: ENV['ZOHO_USER_NAME'],
     password: ENV['ZOHO_PASSWORD']
     

• 验证Heroku环境的凭据加载情况
  登录Heroku控制台执行：

  heroku run rails c
  

  在Rails控制台中测试：

  # 如果用master.key方式
  Rails.application.credentials.zoho # 查看是否返回nil
  # 如果用环境变量方式
  ENV['ZOHO_USER_NAME'] # 查看是否有值
  

• 检查部署日志
  部署时查看Heroku的构建日志，确认是否有凭据加载失败的提示，比如master.key未找到、解密错误等信息。

额外提示 #

你代码中SMTP服务器用的是smtp.gmail.com，但凭据是Zoho的，这里存在不匹配的问题，后续会导致邮件发送失败。Zoho的SMTP服务器应为smtp.zoho.com，建议同步修正。

内容的提问来源于stack exchange，提问作者Macson Soares Rocha