Fix Geo middleware to work properly with multiple requests

The middleware would memoize `Rack::Request`, so the first call that
was received by the middleware would be saved away. This would prevent
subsequent calls from working properly.

changelogs/unreleased-ee/sh-geo-fix-middleware.yml

+---
+title: Fix Geo middleware to work properly with multiple requests
+merge_request:
+author:

lib/gitlab/middleware/readonly_geo.rb

@@ -58,7 +58,7 @@ module Gitlab
       end
 
       def request
-        @request ||= Rack::Request.new(@env)
+        @env['rack.request'] ||= Rack::Request.new(@env)
       end
 
       def last_visited_url
@@ -78,11 +78,11 @@ module Gitlab
       end
 
       def sidekiq_route
-        @request.path.start_with?('/admin/sidekiq')
+        request.path.start_with?('/admin/sidekiq')
       end
 
       def grack_route
-        @request.path.end_with?('.git/git-upload-pack')
+        request.path.end_with?('.git/git-upload-pack')
       end
     end
   end

spec/lib/gitlab/middleware/readonly_geo_spec.rb

@@ -35,7 +35,7 @@ describe Gitlab::Middleware::ReadonlyGeo, lib: true do
   end
 
   subject { described_class.new(fake_app) }
-  let(:request) { @request ||= Rack::MockRequest.new(rack_stack) }
+  let(:request) { Rack::MockRequest.new(rack_stack) }
 
   context 'normal requests to a secondary Gitlab Geo' do
     let(:fake_app) { lambda { |env| [200, { 'Content-Type' => 'text/plain' }, ['OK']] } }
@@ -65,6 +65,16 @@ describe Gitlab::Middleware::ReadonlyGeo, lib: true do
       expect(subject).to disallow_request
     end
 
+    it 'expects a POST Geo request to be allowed after a disallowed request' do
+      response = request.post('/test_request')
+
+      expect(response).to be_a_redirect
+
+      response = request.post("/api/#{API::API.version}/geo/refresh_wikis")
+
+      expect(response).not_to be_a_redirect
+    end
+
     it 'expects DELETE requests to be disallowed' do
       response = request.delete('/test_request')