Route WordPress Blog to Rails Subfolder – Blog Links Not Changed – SEO

I currently have a Rails app, my_app.com, and an associated WordPress blog, blog.my_app.com. They are both running independently on Heroku (i.e. no Apache or Nginx scripting)

I am trying to move the blog into a sub-folder of the Rails app, my_app.com/blog without losing any of the blog’s existing SEO ‘juice’.

I’ve implemented the rack-reverse-proxy gem and the blog’s homepage dutifully appears at http://my_app.com/blog/ as desired. However, all of the links embedded in the blog still point to the sub-domain rather than the app’s blog folder.

How do I configure the blog’s links to http://my_app.com/blog/post1 as opposed to blog.my_app.com/post1??

My config.ru file:

require ::File.expand_path('../config/environment',  __FILE__)

use Rack::ReverseProxy do 
  reverse_proxy(/^/blog(/.*)$/, 'http://my-blog.herokuapp.com$1', opts = {:preserve_host => true})
end

use Rack::Deflater

run MyBlog::Application

In my routes.rb:

constraints domain: 'blog.my_app.com' do 
  get '(*path)' => 'application#blog'
end

get "/blog" => redirect("/blog/")

In my ApplicationController:

def blog
  redirect_to "http://my_app.com{request.fullpath.gsub('/blog','')}", :status => :moved_permanently
end

My WP .htaccess file:

<IfModule mod_rewrite.c>
RewriteEngine  On
RewriteBase /blog/
RewriteRule ^index.php$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>