commit 45da6185655c133fe91d879d15f6f66a8e97c78d
author Luca Milanesio <luca.milanesio@gmail.com> Thu May 12 11:33:30 2016 +0100
committer Luca Milanesio <luca.milanesio@gmail.com> Tue Oct 25 08:00:28 2016 +0100
tree e9aa5cc12c6bbf2183ca074ede7cc7c2bfb20632
parent dce95ae8a9af3dc228e0b696d31f53ab331bfee9

Allow to listen to Web login/logout events

When using Gerrit with external authentication systems (OAuth or other)
it would be necessary to enforce additional requirements (e.g. 2-factor)
or introduce some plug-in specific post-login screen for finalising
the user's on boarding.

Similarly when the user logs out, we may need to invalidate its token
from an external SSO system or to perform some other plugin-specific
operations or even simply request a feedback.

With the introduction of this new extension point WebLoginListener
it is possible to filter the HTTP response and override the status
code to redirect or perform additional adjustments to comply with
the company or the plugin's requirements.

It is possible to experiment this new extension with a simple
Groovy scripting plugin (see below).

```
import com.google.gerrit.extensions.annotations.*
import javax.servlet.http.*
import com.google.inject.*
import com.google.gerrit.httpd.*
import com.google.gerrit.server.*

@Singleton
@Listen
public class MyPostLogin implements WebLoginListener {

  public void onLogin(IdentifiedUser user,
                      HttpServletRequest req,
                      HttpServletResponse resp) {
    println "Post-login user=$user"
    resp.sendRedirect("https://twophase.mycompany.com/auth")
  }
  public void onLogout(IdentifiedUser user,
                       HttpServletRequest req,
                       HttpServletResponse resp) {
    println "Post-logout user=$user"
    resp.sendRedirect("https://ssologout.mycompany.com")
  }
}
```

Change-Id: I76e8ec040072e317061234665a0d865927da55b9