RANGER-5499: Revert Filter and use GenericFilterBean with PostConstruct

(cherry picked from commit 371b5de)

Author: kumaab

security-admin/src/main/java/org/apache/ranger/security/web/filter/RangerHeaderPreAuthFilter.java

@@ -32,10 +32,10 @@
 import org.springframework.security.core.userdetails.User;
 import org.springframework.security.core.userdetails.UserDetails;
 import org.springframework.security.web.authentication.WebAuthenticationDetails;
+import org.springframework.web.filter.GenericFilterBean;
 
-import javax.servlet.Filter;
+import javax.annotation.PostConstruct;
 import javax.servlet.FilterChain;
-import javax.servlet.FilterConfig;
 import javax.servlet.ServletException;
 import javax.servlet.ServletRequest;
 import javax.servlet.ServletResponse;
@@ -46,7 +46,7 @@
 import java.util.Collection;
 import java.util.List;
 
-public class RangerHeaderPreAuthFilter implements Filter {
+public class RangerHeaderPreAuthFilter extends GenericFilterBean {
     private static final Logger LOG = LoggerFactory.getLogger(RangerHeaderPreAuthFilter.class);
 
     public static final String PROP_HEADER_AUTH_ENABLED    = "ranger.admin.authn.header.enabled";
@@ -59,24 +59,12 @@ public class RangerHeaderPreAuthFilter implements Filter {
     @Autowired
     UserMgr userMgr;
 
-    public RangerHeaderPreAuthFilter() {
-        loadConfiguration();
-    }
-
-    @Override
-    public void init(FilterConfig config) throws ServletException {
-        loadConfiguration();
-    }
-
-    private void loadConfiguration() {
+    @PostConstruct
+    protected void initialize() {
         headerAuthEnabled  = PropertiesUtil.getBooleanProperty(PROP_HEADER_AUTH_ENABLED, false);
         userNameHeaderName = PropertiesUtil.getProperty(PROP_USERNAME_HEADER_NAME);
     }
 
-    @Override
-    public void destroy() {
-    }
-
     @Override
     public void doFilter(ServletRequest request, ServletResponse response, FilterChain chain) throws IOException, ServletException {
         if (headerAuthEnabled) {

security-admin/src/test/java/org/apache/ranger/security/web/filter/TestRangerHeaderPreAuthFilter.java

@@ -75,7 +75,7 @@ public void testDoFilter_disabled_passesThrough() throws Exception {
         UserMgr                   userMgr = mock(UserMgr.class);
 
         filter.userMgr = userMgr;
-        filter.init(null);
+        filter.initialize();
 
         HttpServletRequest  request  = mock(HttpServletRequest.class);
         HttpServletResponse response = mock(HttpServletResponse.class);
@@ -97,7 +97,7 @@ public void testDoFilter_enabled_missingUsername_passesThrough() throws Exceptio
         UserMgr                   userMgr = mock(UserMgr.class);
 
         filter.userMgr = userMgr;
-        filter.init(null);
+        filter.initialize();
 
         HttpServletRequest  request  = mock(HttpServletRequest.class);
         HttpServletResponse response = mock(HttpServletResponse.class);
@@ -121,7 +121,7 @@ public void testDoFilter_enabled_withUsername_setsAuthenticationFromRangerDbRole
         UserMgr                   userMgr = mock(UserMgr.class);
 
         filter.userMgr = userMgr;
-        filter.init(null);
+        filter.initialize();
 
         when(userMgr.getRolesByLoginId("joeuser")).thenReturn(Arrays.asList("ROLE_SYS_ADMIN", "ROLE_USER"));
 
@@ -160,7 +160,7 @@ public void testDoFilter_enabled_existingAuthenticatedContext_doesNotOverrideAut
         UserMgr                   userMgr = mock(UserMgr.class);
 
         filter.userMgr = userMgr;
-        filter.init(null);
+        filter.initialize();
 
         UsernamePasswordAuthenticationToken existingAuth = new UsernamePasswordAuthenticationToken("existing-user", "pwd", Collections.singletonList(new SimpleGrantedAuthority("test-role")));