[JENKINS-75602] Report URL in update center failure messages

core/src/main/java/hudson/model/DownloadService.java

@@ -128,6 +128,13 @@ public static String loadJSON(URL src) throws IOException {
             } else {
                 throw new IOException("Could not find JSON in " + src);
             }
+        } catch (IOException ioe) {
+            // Include basename of exception and original message text
+            // in the new message so that the person reading the
+            // message understands the exception type and the text
+            // provided by the original exception.
+            String ioeMessage = ioe.getClass().getSimpleName() + ": " + ioe.getMessage();
+            throw new IOException("Could not load JSON from " + src + " due to " + ioeMessage);
         }
     }
 
@@ -154,6 +161,13 @@ public static String loadJSONHTML(URL src) throws IOException {
             } else {
                 throw new IOException("Could not find JSON in " + src);
             }
+        } catch (IOException ioe) {
+            // Include basename of exception and original message text
+            // in the new message so that the person reading the
+            // message understands the exception type and the text
+            // provided by the original exception.
+            String ioeMessage = ioe.getClass().getSimpleName() + ": " + ioe.getMessage();
+            throw new IOException("Could not load JSON as HTML from " + src + " due to " + ioeMessage);
         }
     }
 

test/src/test/java/hudson/model/DownloadServiceTest.java

@@ -1,14 +1,19 @@
 package hudson.model;
 
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.Matchers.containsString;
 import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import edu.umd.cs.findbugs.annotations.NonNull;
 import hudson.model.DownloadService.Downloadable;
 import hudson.tasks.Ant.AntInstaller;
 import hudson.tasks.Maven;
 import hudson.tools.DownloadFromUrlInstaller;
 import hudson.tools.ToolInstallation;
+import java.io.IOException;
+import java.net.URI;
 import java.net.URL;
 import java.util.ArrayList;
 import java.util.List;
@@ -38,6 +43,26 @@ private static void assertRoots(String expected, URL resource) throws Exception
         assertEquals(expected, new TreeSet<>(keySet).toString());
     }
 
+    @WithoutJenkins
+    @Test
+    void testLoadJSONException() throws Exception {
+        String badHostname = "bad.updates.jenkins.io"; // Non-existent host
+        URL badURL = new URI("https://" + badHostname + "/update-center.json").toURL();
+        IOException e = assertThrows(IOException.class, () -> DownloadService.loadJSON(badURL));
+        assertThat(e.getMessage(), containsString(badURL.toString()));
+        assertThat(e.getMessage(), containsString("due to UnknownHostException:"));
+    }
+
+    @WithoutJenkins
+    @Test
+    void testLoadJSONHTMLException() throws Exception {
+        String badHostname = "bad.updates.jenkins.io"; // Non-existent host
+        URL badURL = new URI("https://" + badHostname + "/update-center.json").toURL();
+        IOException e = assertThrows(IOException.class, () -> DownloadService.loadJSONHTML(badURL));
+        assertThat(e.getMessage(), containsString(badURL.toString()));
+        assertThat(e.getMessage(), containsString("due to UnknownHostException:"));
+    }
+
     @Test
     void testReduceFunctionWithMavenJsons() throws Exception {
         URL resource1 = DownloadServiceTest.class.getResource("hudson.tasks.Maven.MavenInstaller1.json");