Rework single-sign-on to cope with Jetty 11

Sharing the session handler between contexts leads to an NPE,
because startup of the first context now reaches into the
lifecycle of the second webapp, which has not started yet.
SessionHandler objects, which carry context-specific
lifecycle information, must not be shared between contexts.

libs/gretty-runner-jetty11/src/main/groovy/org/akhikhl/gretty/JettyConfigurerImpl.groovy

@@ -36,7 +36,6 @@ class JettyConfigurerImpl implements JettyConfigurer {
   private static final Logger log = LoggerFactory.getLogger(JettyConfigurerImpl)
 
   private SSOAuthenticatorFactory ssoAuthenticatorFactory
-  private SessionHandler sharedSessionHandler
 
   @Override
   def addLifeCycleListener(lifecycle, listener) {
@@ -175,12 +174,9 @@ class JettyConfigurerImpl implements JettyConfigurer {
   void configureSessionManager(server, context, Map serverParams, Map webappParams) {
     SessionHandler sessionHandler
     if(serverParams.singleSignOn) {
-      sessionHandler = sharedSessionHandler
-      if(sessionHandler == null) {
-        sessionHandler = sharedSessionHandler = new SessionHandler()
-        sessionHandler.setMaxInactiveInterval(60 * 30) // 30 minutes
-        sessionHandler.getSessionCookieConfig().setPath('/')
-      }
+      sessionHandler = new SingleSignOnSessionHandler()
+      sessionHandler.setMaxInactiveInterval(60 * 30) // 30 minutes
+      sessionHandler.getSessionCookieConfig().setPath('/')
     } else {
       sessionHandler = new SessionHandler()
       sessionHandler.setMaxInactiveInterval(60 * 30) // 30 minutes

libs/gretty-runner-jetty11/src/main/groovy/org/akhikhl/gretty/SingleSignOnSessionHandler.groovy

@@ -0,0 +1,31 @@
+package org.akhikhl.gretty
+
+import org.eclipse.jetty.server.session.Session
+import org.eclipse.jetty.server.session.SessionHandler
+
+class SingleSignOnSessionHandler extends SessionHandler {
+
+    @Override
+    Session getSession(String id) {
+        Session session = getLocalSession(id)
+        if (session == null) {
+            for (SessionHandler handler : getSessionIdManager().getSessionHandlers()) {
+
+                if (handler == this || !(handler instanceof SingleSignOnSessionHandler)) {
+                    continue
+                }
+
+                session = ((SingleSignOnSessionHandler) handler).getLocalSession(id)
+                if (session != null) {
+                    break
+                }
+            }
+        }
+
+        return session
+    }
+
+    private Session getLocalSession(String id) {
+        return super.getSession(id)
+    }
+}