title: How to read XML appSettings from external file?
body: <p>There are a lot of similar questions and I have looked at every one I could find, to no avail.</p>
  
  <p>I'm storing API keys for Google+ authentication in a .config file outside of my solution (in the same level as the solution folder).</p>
  
  <p>I'm attempting to read the values back in Startup.Auth.cs, like so:</p>
  
  <pre><code>public void ConfigureAuth(IAppBuilder app)
  {
      app.UseGoogleAuthentication(new GoogleOAuth2AuthenticationOptions()
      {
          ClientId = WebConfigurationManager.AppSettings.Get("GoogleClientId"),
          ClientSecret = WebConfigurationManager.AppSettings.Get("GoogleClientSecret")
      });
  }
  </code></pre>
  
  <p>Root Web.config:</p>
  
  <pre><code>&lt;appSettings file="..\Secrets.config"&gt; &lt;!-- Path is correct, relative to Web.config --&gt;
    &lt;add key="webpages:Version" value="3.0.0.0" /&gt;
    &lt;add key="webpages:Enabled" value="false" /&gt;
    &lt;add key="ClientValidationEnabled" value="true" /&gt;
    &lt;add key="UnobtrusiveJavaScriptEnabled" value="true" /&gt;
  &lt;/appSettings&gt;
  </code></pre>
  
  <p>Secrets.config:</p>
  
  <pre><code>&lt;configuration&gt;
    &lt;appSettings&gt;
      &lt;add key="GoogleClientId" value="shh" /&gt;
      &lt;add key="GoogleClientSecret" value="shh" /&gt;
    &lt;/appSettings&gt;
  &lt;/configuration&gt;
  </code></pre>