您可以将每个提供程序的设置存储在db中，然后在请求时的设置阶段配置omniauth。例如：

SETUP_PROC = lambda do |env| 
  request = Rack::Request.new(env)
  user = User.find_by_subdomain(request.subdomain)
  env['omniauth.strategy'].options[:consumer_key] = user.consumer_key
  env['omniauth.strategy'].options[:consumer_secret] = user.consumer_secret
end

use OmniAuth::Builder.new do
  provider :twitter, :setup => SETUP_PROC
end

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请参阅https://github.com/intridea/omniauth/wiki/Setup-Phase了解更多信息。

通过Devise + OmniAuth使用多个SAML IDP：
遵循这个单一IDP的官方指南。
https://github.com/omniauth/omniauth-saml#devise-integration
一旦你有你的SP与单IDP工作，做以下调整
1.在devise初始化器中

config.omniauth :first, {
                          name: :first,
                          strategy_class: ::OmniAuth::Strategies::SAML,
                          #Rest of the config as per omniauth-saml guide  
                          assertion_consumer_service_url: '/users/auth/first/callback'}


config.omniauth :second, {
                           name: :second,
                           strategy_class: ::OmniAuth::Strategies::SAML,
                           #Rest of the config as per omniauth-saml guide
                           assertion_consumer_service_url: '/users/auth/second/callback'}

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1.在Users::OmniauthCallbacksController中，添加名为first和second的操作，而不是官方指南中建议的saml。
1.在您的User型号中：

devise :omniauthable, omniauth_providers: [:first, :second]

型
如果所有配置都正确，您现在已经为两个IDP配置了SP。

Rails.application.config.middleware.use OmniAuth::Builder do
   provider :saml,
     name: "first",
     assertion_consumer_service_url: "/auth/first/callback",
     issuer: "your-app",
     idp_sso_target_url: "first.com/idp"
     idp_cert_fingerprint: "E7:91:B2:E1:...",
     name_identifier_format: "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress"
   provider :saml,
     name: "second",
     assertion_consumer_service_url: "/auth/second/callback",
     issuer: "your-app",
     idp_sso_target_url: "second.com/idp",
     idp_cert_fingerprint: "E7:91:B2:E1:...",
     name_identifier_format: "urn:oasis:names:tc:SAML:1.1:nameid-format:emailAddress"

 end

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如果在联邦上下文中使用应用程序，则很可能存在元数据源，例如saml2int.org配置文件中规定的元数据。此元数据包含用于填充IDP发现（并自动配置所有IDP）的数据。似乎omniauth-saml不支持SAML Metadata规范，因此某种SAML代理是替代方案。