@sscarduzio we recently started using Windows 2012. I have the same setup as before (from Win 2008 R2) and have started getting similar error as originally reported when using Win 2008 R2.
[2017-10-23T19:15:10,901][INFO ][o.e.p.r.e.SettingsManagerImpl] Could not find settings in config\readonlyrest.yml, falling back to elasticsearch.yml (access denied ("java.io.FilePermission" "config\readonlyrest.yml" "read"))
To fix this, temporarily, I had to moved the settings back the settings to elasticsearch.yml file. Then it started working - but only the authorization and authentication was working. Enabling https was throwing error that keystore path is incorrect. I think that it is definitely similar error.
[2017-10-23T19:15:16,360][INFO ][o.e.p.r.e.SSLTransportNetty4] SSL: attempting with JKS keystore..
[2017-10-23T19:15:16,361][ERROR][o.e.p.r.e.SSLTransportNetty4] Failed to load SSL certs and keys from JKS Keystore!
[2017-10-23T19:15:16,361][ERROR][o.e.p.r.e.SSLTransportNetty4] Check the JKS Keystore path is correct: config/my_keystore.jks
I originally had the keystore file path as mentioned below in first line (this works in Win 2008 R2). I then changed it to give the absolute path and then the SSL also started working.
keystore_file: D:\Apps\Program Files\Elasticsearch-5.5.1\config\my_keystore.jks
Looks like ROR has issue reading relative path and its similar issue in both reading readonlyrest.yml file as well as the keystore file. In my case, we have the config folder under elasticsearch installation folder itself. So we dont have a separate entry for path.conf. I think that ROR is unable to resolve the config path and hence subsequently fails to resolve the paths for readonlyrest.yml and keystore files. When you dont find readonlyrest.yml file, can you please also add a debug message to show to what folder location does the “$ES_HOME/config” resolves to? This might throw some additional light.