Add second proxy setting

app/lib/request.rb

@@ -69,6 +69,7 @@ def initialize(verb, url, **options)
     @http_client = options.delete(:http_client)
     @options     = options.merge(socket_class: use_proxy? ? ProxySocket : Socket)
     @options     = @options.merge(Rails.configuration.x.http_client_proxy) if use_proxy?
+    @options     = @options.merge(Rails.configuration.x.http_client_second_proxy) if use_second_proxy?
     @headers     = {}
 
     raise Mastodon::HostValidationError, 'Instance does not support hidden service connections' if block_hidden_service?
@@ -181,6 +182,10 @@ def use_proxy?
     Rails.configuration.x.http_client_proxy.present?
   end
 
+  def use_second_proxy?
+    Rails.configuration.x.http_client_second_proxy.present? && Rails.configuration.x.domain_to_use_second_proxy.include?(Addressable::URI.parse(@url).host)
+  end
+
   def block_hidden_service?
     !Rails.configuration.x.access_to_hidden_service && /\.(onion|i2p)$/.match?(@url.host)
   end

config/initializers/http_client_proxy.rb

@@ -18,5 +18,24 @@
     }.compact
   end
 
+  if ENV['SECOND_HTTP_PROXY'].present? && ENV['DOMAIN_TO_USE_SECOND_PROXY'].present?
+    proxy = URI.parse(ENV['SECOND_HTTP_PROXY'])
+
+    raise "Unsupported proxy type: #{proxy.scheme}" unless %w(http https).include? proxy.scheme
+    raise "No proxy host" unless proxy.host
+
+    host = proxy.host
+    host = host[1...-1] if host[0] == '[' # for IPv6 address
+
+    config.x.http_client_second_proxy[:proxy] = {
+      proxy_address: host,
+      proxy_port: proxy.port,
+      proxy_username: proxy.user,
+      proxy_password: proxy.password,
+    }.compact
+
+    config.x.domain_to_use_second_proxy = ENV['DOMAIN_TO_USE_SECOND_PROXY'].split(',')
+  end
+
   config.x.access_to_hidden_service = ENV['ALLOW_ACCESS_TO_HIDDEN_SERVICE'] == 'true'
 end