diff --git a/Gemfile b/Gemfile
index ba51241..ad1b1eb 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,6 +7,8 @@ if RUBY_VERSION < '2.7'
 else
   gem 'activesupport', '>= 5.2'
 end
+# Rack 3.x requires Ruby 2.6+ (Enumerable#to_h with block)
+gem 'rack', '< 3' if RUBY_VERSION < '2.6'
 gem "irb", "~> 1.1"
 
 # Specify your gem's dependencies in aptible-api.gemspec
diff --git a/lib/aptible/api/container.rb b/lib/aptible/api/container.rb
index 70c2787..cd0787f 100644
--- a/lib/aptible/api/container.rb
+++ b/lib/aptible/api/container.rb
@@ -3,6 +3,8 @@ module Api
     class Container < Resource
       belongs_to :release
       belongs_to :vhost
+      has_many :vhosts
+      has_many :container_vhost_memberships
       belongs_to :log_drain
       belongs_to :metric_drain
       has_many :release_alterations
diff --git a/lib/aptible/api/container_vhost_membership.rb b/lib/aptible/api/container_vhost_membership.rb
new file mode 100644
index 0000000..8bc2156
--- /dev/null
+++ b/lib/aptible/api/container_vhost_membership.rb
@@ -0,0 +1,12 @@
+module Aptible
+  module Api
+    class ContainerVhostMembership < Resource
+      belongs_to :container
+      belongs_to :vhost
+
+      field :id
+      field :created_at, type: Time
+      field :updated_at, type: Time
+    end
+  end
+end
diff --git a/lib/aptible/api/resource.rb b/lib/aptible/api/resource.rb
index d952e79..867f65d 100644
--- a/lib/aptible/api/resource.rb
+++ b/lib/aptible/api/resource.rb
@@ -24,6 +24,7 @@ def root_url
 require 'aptible/api/certificate'
 require 'aptible/api/configuration'
 require 'aptible/api/container'
+require 'aptible/api/container_vhost_membership'
 require 'aptible/api/database'
 require 'aptible/api/database_image'
 require 'aptible/api/deployment'
diff --git a/lib/aptible/api/version.rb b/lib/aptible/api/version.rb
index 7810575..50cb095 100644
--- a/lib/aptible/api/version.rb
+++ b/lib/aptible/api/version.rb
@@ -1,5 +1,5 @@
 module Aptible
   module Api
-    VERSION = '1.12.2'.freeze
+    VERSION = '1.12.3'.freeze
   end
 end