AMBARI-11473 - Fix Tez view to surface underlying errors resulting from failure to communicate with timeline (Hitesh Shah via tbeerbower)

contrib/views/tez/pom.xml

@@ -23,8 +23,8 @@
   </parent>
   <properties>
     <ambari.dir>${project.parent.parent.parent.basedir}</ambari.dir>
-    <tez.view.version>0.6.0-SNAPSHOT</tez.view.version>
-    <tez.version>0.6.0</tez.version>
+    <tez.view.version>0.7.0-SNAPSHOT</tez.view.version>
+    <tez.version>0.7.0</tez.version>
   </properties>
   <modelVersion>4.0.0</modelVersion>
   <groupId>org.apache.ambari.contrib.views</groupId>
@@ -156,6 +156,12 @@
       <version>1.8</version>
     </dependency>
 
+    <dependency>
+      <groupId>com.sun.jersey</groupId>
+      <artifactId>jersey-core</artifactId>
+      <version>1.8</version>
+    </dependency>
+
     <dependency>
       <groupId>org.apache.ambari</groupId>
       <artifactId>ambari-views</artifactId>
@@ -174,5 +180,17 @@
       <artifactId>guice</artifactId>
     </dependency>
 
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-api</artifactId>
+      <version>1.7.5</version>
+    </dependency>
+
+    <dependency>
+      <groupId>commons-io</groupId>
+      <artifactId>commons-io</artifactId>
+      <version>2.4</version>
+    </dependency>
+
   </dependencies>
 </project>

contrib/views/tez/src/main/java/org/apache/ambari/view/tez/ProxyServlet.java

@@ -18,11 +18,14 @@
 
 package org.apache.ambari.view.tez;
 
+import org.apache.ambari.view.URLConnectionProvider;
 import org.apache.ambari.view.ViewContext;
-import org.apache.ambari.view.HttpImpersonator;
-import org.apache.ambari.view.ImpersonatorSetting;
+import org.apache.commons.io.IOUtils;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
 
 import java.io.IOException;
+import java.io.InputStream;
 import java.io.PrintWriter;
 import javax.servlet.ServletConfig;
 import javax.servlet.ServletContext;
@@ -30,26 +33,33 @@ import javax.servlet.ServletException;
 import javax.servlet.http.HttpServlet;
 import javax.servlet.http.HttpServletRequest;
 import javax.servlet.http.HttpServletResponse;
+import javax.ws.rs.HttpMethod;
+import javax.ws.rs.core.Response;
+import javax.ws.rs.core.Response.Status;
+
+import java.net.HttpURLConnection;
 import java.net.URLDecoder;
+import java.util.Collections;
+import java.util.Map;
 
 /**
  * Simple servlet for proxying requests with doAs impersonation.
  */
 public class ProxyServlet extends HttpServlet {
 
-  private ViewContext viewContext;
-  private HttpImpersonator impersonator;
-  private ImpersonatorSetting impersonatorSetting;
+  private static final Logger LOG = LoggerFactory.getLogger(ProxyServlet.class);
+
+  private URLConnectionProvider urlConnectionProvider;
+  private final static String nullData = null;
+  private final static Map<String, String> emptyHeaders = Collections.EMPTY_MAP;
 
   @Override
   public void init(ServletConfig config) throws ServletException {
     super.init(config);
 
     ServletContext context = config.getServletContext();
-    viewContext = (ViewContext) context.getAttribute(ViewContext.CONTEXT_ATTRIBUTE);
-
-    this.impersonator = viewContext.getHttpImpersonator();
-    this.impersonatorSetting = viewContext.getImpersonatorSetting();
+    ViewContext viewContext = (ViewContext) context.getAttribute(ViewContext.CONTEXT_ATTRIBUTE);
+    this.urlConnectionProvider = viewContext.getURLConnectionProvider();
   }
 
   @Override
@@ -58,14 +68,63 @@ public class ProxyServlet extends HttpServlet {
 
     response.setContentType(request.getContentType());
 
-    // Getting the result is super simply by using the impersonator and the default values in the factory.
-    String result = this.impersonator.requestURL(urlToRead, "GET", this.impersonatorSetting);
-    Boolean notFound = result == "" || result.indexOf("\"exception\":\"NotFoundException\"") != -1;
+    if (LOG.isDebugEnabled()) {
+      LOG.debug("Requesting data from ATS, url=" + urlToRead);
+    }
+
+    InputStream resultInputStream;
+    String result = "";
+    // When in doubt, assume error
+    int responseCode = Status.INTERNAL_SERVER_ERROR.getStatusCode();
+    HttpURLConnection connection;
+    try {
+      // Use nullData as null string and null inputstream cannot be disambiguated
+      // URL Stream Provider will automatically inject the doAs param with the current
+      // user's info
+      connection = urlConnectionProvider.getConnectionAsCurrent(urlToRead,
+          HttpMethod.GET, nullData, emptyHeaders);
+      responseCode = connection.getResponseCode();
 
-    response.setStatus(notFound ? HttpServletResponse.SC_NOT_FOUND : HttpServletResponse.SC_OK);
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Received response from ATS, url=" + urlToRead
+            + ", responseCode=" + responseCode);
+      }
 
+      if (responseCode >= Response.Status.BAD_REQUEST.getStatusCode()) {
+        resultInputStream = connection.getErrorStream();
+      } else {
+        resultInputStream = connection.getInputStream();
+      }
+
+      result = IOUtils.toString(resultInputStream);
+      if (LOG.isDebugEnabled()) {
+        LOG.debug("Received response from ATS, url=" + urlToRead
+            + ", responseCode=" + responseCode
+            + ", responseBodyLen=" + result.length());
+      }
+
+    } catch (IOException e) {
+      // We might kill the ambari server by logging this error every time a call fails
+      if (LOG.isDebugEnabled()) {
+        LOG.warn("Failed to retrieve data from ATS, url=" + urlToRead, e);
+      }
+      responseCode = Status.INTERNAL_SERVER_ERROR.getStatusCode();
+      result = e.toString();
+    } catch (Exception e) {
+      LOG.warn("Unknown Exception: Failed to retrieve data from ATS, url=" + urlToRead, e);
+      responseCode = Status.INTERNAL_SERVER_ERROR.getStatusCode();
+      result = e.toString();
+    } finally {
+      // not disconnecting http conn as it might be cached/re-used internally
+      // in the UrlStreamProvider
+    }
+
+    response.setStatus(responseCode);
     PrintWriter writer = response.getWriter();
-    writer.print(result);
+    if (result != null) {
+      writer.print(result);
+    }
   }
+
 }