YARN-7961. Improve status message for YARN service.

           Contributed by Gour Saha
(cherry picked from commit 7fe3214d4bb810c0da18dd936875b4e2588ba518)

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services-api/src/main/java/org/apache/hadoop/yarn/service/client/ApiServiceClient.java

@@ -479,6 +479,13 @@ public class ApiServiceClient extends AppAdminClient {
     try {
       ClientResponse response = getApiClient(getServicePath(appName))
           .get(ClientResponse.class);
+      if (response.getStatus() == 404) {
+        StringBuilder sb = new StringBuilder();
+        sb.append(" Service ");
+        sb.append(appName);
+        sb.append(" not found");
+        return sb.toString();
+      }
       if (response.getStatus() != 200) {
         StringBuilder sb = new StringBuilder();
         sb.append(appName);

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services-api/src/main/java/org/apache/hadoop/yarn/service/webapp/ApiServer.java

@@ -186,7 +186,7 @@ public class ApiServer {
     ServiceStatus serviceStatus = new ServiceStatus();
     try {
       if (appName == null) {
-        throw new IllegalArgumentException("Service name can not be null.");
+        throw new IllegalArgumentException("Service name cannot be null.");
       }
       UserGroupInformation ugi = getProxyUser(request);
       LOG.info("GET: getService for appName = {} user = {}", appName, ugi);
@@ -194,12 +194,16 @@ public class ApiServer {
       return Response.ok(app).build();
     } catch (AccessControlException e) {
       return formatResponse(Status.FORBIDDEN, e.getMessage());
-    } catch (IllegalArgumentException |
-        FileNotFoundException e) {
+    } catch (IllegalArgumentException e) {
       serviceStatus.setDiagnostics(e.getMessage());
       serviceStatus.setCode(ERROR_CODE_APP_NAME_INVALID);
       return Response.status(Status.NOT_FOUND).entity(serviceStatus)
           .build();
+    } catch (FileNotFoundException e) {
+      serviceStatus.setDiagnostics("Service " + appName + " not found");
+      serviceStatus.setCode(ERROR_CODE_APP_NAME_INVALID);
+      return Response.status(Status.NOT_FOUND).entity(serviceStatus)
+          .build();
     } catch (IOException | InterruptedException e) {
       LOG.error("Get service failed: {}", e);
       return formatResponse(Status.INTERNAL_SERVER_ERROR, e.getMessage());

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services-api/src/test/java/org/apache/hadoop/yarn/service/ServiceClientTest.java

@@ -31,6 +31,7 @@ import org.apache.hadoop.yarn.service.client.ServiceClient;
 import org.apache.hadoop.yarn.service.utils.ServiceApiUtil;
 import org.apache.hadoop.yarn.service.utils.SliderFileSystem;
 
+import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.util.ArrayList;
 import java.util.List;
@@ -81,11 +82,11 @@ public class ServiceClientTest extends ServiceClient {
   }
 
   @Override
-  public Service getStatus(String appName) {
-    if (appName != null && appName.equals("jenkins")) {
+  public Service getStatus(String appName) throws FileNotFoundException {
+    if ("jenkins".equals(appName)) {
       return goodServiceStatus;
     } else {
-      throw new IllegalArgumentException();
+      throw new FileNotFoundException("Service " + appName + " not found");
     }
   }
 

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services-api/src/test/java/org/apache/hadoop/yarn/service/TestApiServer.java

@@ -41,6 +41,7 @@ import org.apache.hadoop.yarn.service.api.records.Resource;
 import org.apache.hadoop.yarn.service.api.records.Service;
 import org.apache.hadoop.yarn.service.api.records.ServiceState;
 import org.apache.hadoop.yarn.service.api.records.ServiceStatus;
+import org.apache.hadoop.yarn.service.conf.RestApiConstants;
 import org.apache.hadoop.yarn.service.webapp.ApiServer;
 import org.junit.After;
 import org.junit.Before;
@@ -151,10 +152,17 @@ public class TestApiServer {
 
   @Test
   public void testBadGetService() {
-    final Response actual = apiServer.getService(request, "no-jenkins");
+    final String serviceName = "nonexistent-jenkins";
+    final Response actual = apiServer.getService(request, serviceName);
     assertEquals("Get service is ",
         Response.status(Status.NOT_FOUND).build().getStatus(),
         actual.getStatus());
+    ServiceStatus serviceStatus = (ServiceStatus) actual.getEntity();
+    assertEquals("Response code don't match",
+        RestApiConstants.ERROR_CODE_APP_NAME_INVALID, serviceStatus.getCode());
+    assertEquals("Response diagnostics don't match",
+        "Service " + serviceName + " not found",
+        serviceStatus.getDiagnostics());
   }
 
   @Test
@@ -163,6 +171,11 @@ public class TestApiServer {
     assertEquals("Get service is ",
         Response.status(Status.NOT_FOUND).build().getStatus(),
         actual.getStatus());
+    ServiceStatus serviceStatus = (ServiceStatus) actual.getEntity();
+    assertEquals("Response code don't match",
+        RestApiConstants.ERROR_CODE_APP_NAME_INVALID, serviceStatus.getCode());
+    assertEquals("Response diagnostics don't match",
+        "Service name cannot be null.", serviceStatus.getDiagnostics());
   }
 
   @Test

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-applications/hadoop-yarn-services-api/src/test/java/org/apache/hadoop/yarn/service/client/TestApiServiceClient.java

@@ -59,7 +59,12 @@ public class TestApiServiceClient {
     protected void doGet(HttpServletRequest req, HttpServletResponse resp)
         throws ServletException, IOException {
       System.out.println("Get was called");
-      resp.setStatus(HttpServletResponse.SC_OK);
+      if (req.getPathInfo() != null
+          && req.getPathInfo().contains("nonexistent-app")) {
+        resp.setStatus(HttpServletResponse.SC_NOT_FOUND);
+      } else {
+        resp.setStatus(HttpServletResponse.SC_OK);
+      }
     }
 
     @Override
@@ -139,6 +144,18 @@ public class TestApiServiceClient {
     }
   }
 
+  @Test
+  public void testStatus() {
+    String appName = "nonexistent-app";
+    try {
+      String result = asc.getStatusString(appName);
+      assertEquals("Status reponse don't match",
+          " Service " + appName + " not found", result);
+    } catch (IOException | YarnException e) {
+      fail();
+    }
+  }
+
   @Test
   public void testStop() {
     String appName = "example-app";