Context

In any debugging environment development or preview,

• database has account super domain set to example.com
• you access the UI or with another super domain like proxied-domain.com

You still want to point your browser to *http://provider-admin.proxied-domain.com*
and expect it to work.

In a "proxied" request, we used to monkey patch request.host with
ThreeScale::Middleware::DevDomain and ThreeScale::DevDomain, leading to:

• weird behavior
• feature needing to know the environment.
  Is it preview or development or production?
• monkey patching feature to make it testable locally or in preview
• library failures in preview (sidekiq-web not working well)

Using a prroxy as a solution?

Why not using a proxy (e.g. nginx) to replace the URL?

Well, it would not work for server responses.
When the code is using account.domain or the likes, it will then use
provider-admin.3scale.net instead of provider-admin.example.com

Features that do not work well

• sidekiq web and any middleware that relies on request.host
• email views will render link with the incorrect domain:
  url are rendered with host: account.domain
• service discovery Authentication needs to craft some the url
  with :host option
• SSO login will not work for the same reason
• whenever you use url_for(host: account.domain) there is an issue

So what solution?

This module adds some convenient methods to be used in the correct context
i.e. the writer will have the responsibility to use the correct method

• {Account#external_domain}

  or

  {Account#internal_domain}
• {Account#external_admin_domain}

  or

  {Account#internal_admin_domain}

Most of the use cases:

• in the context of a request, use Account#internal_* methods
• in the context of a response, use Account#external_* methods

Examples:

Config file: config/domain_substitution.yml

      development: 
        enabled: true
        request_pattern: "\\.proxied-domain\\.com"
        request_replacement: ".example.com"
        response_pattern: "\\.example\\.com"
        response_replacement: ".proxied-domain.com"
  

In Ruby:

      request.host
      # => provider-admin.proxied-domain.com
  
      request.internal_host
      # => provider-admin.example.com
  
      account.provider?
      # => true
  
      account['domain']
      # => "provider.example.com"
  
      account['self_domain']
      # => "provider-admin.example.com"
  
      account.external_domain
      # => "provider.proxied-domain.com"
  
      account.external_admin_domain
      # => "provider-admin.proxied-domain.com"