add canonical host middleware

Gemfile

@@ -21,6 +21,7 @@ gem "jbuilder", "~> 2.11"
 gem "nilify_blanks", "~> 1.4"
 gem "pg", "~> 1.2"
 gem "puma", "~> 5.5"
+gem "rack-canonical-host", "~> 1.1", require: false
 gem "redis", "~> 4.5"
 gem "rspec-rails", "~> 5.0"
 gem "sprockets-rails", "~> 3.4"

Gemfile.lock

@@ -73,6 +73,8 @@ GEM
       i18n (>= 1.6, < 2)
       minitest (>= 5.1)
       tzinfo (~> 2.0)
+    addressable (2.8.0)
+      public_suffix (>= 2.0.2, < 5.0)
     bindex (0.8.1)
     bootsnap (1.9.4)
       msgpack (~> 1.0)
@@ -144,10 +146,14 @@ GEM
     nokogiri (1.13.0-x86_64-linux)
       racc (~> 1.4)
     pg (1.2.3)
+    public_suffix (4.0.6)
     puma (5.5.2)
       nio4r (~> 2.0)
     racc (1.6.0)
     rack (2.2.3)
+    rack-canonical-host (1.1.0)
+      addressable (> 0, < 3)
+      rack (>= 1.0.0, < 3)
     rack-test (1.1.0)
       rack (>= 1.0, < 3)
     rails (7.0.1)
@@ -247,6 +253,7 @@ DEPENDENCIES
   nilify_blanks (~> 1.4)
   pg (~> 1.2)
   puma (~> 5.5)
+  rack-canonical-host (~> 1.1)
   rails (~> 7.0)
   redis (~> 4.5)
   rspec-rails (~> 5.0)

config.ru

@@ -1,6 +1,7 @@
 # This file is used by Rack-based servers to start the application.
-
 require_relative "config/environment"
+require "rack/canonical_host"
 
+use Rack::CanonicalHost, ENV["HOST"] if ENV.key?("HOST")
 run Rails.application
 Rails.application.load_server