Implement ServiceDownException for case GitHub's API is down

src/main/java/org/kohsuke/github/GitHubConnectorResponseErrorHandler.java

@@ -3,12 +3,15 @@
 import org.jetbrains.annotations.NotNull;
 import org.kohsuke.github.connector.GitHubConnectorResponse;
 
+import java.io.BufferedReader;
 import java.io.FileNotFoundException;
 import java.io.IOException;
+import java.io.InputStreamReader;
 
 import javax.annotation.Nonnull;
 
 import static java.net.HttpURLConnection.HTTP_BAD_REQUEST;
+import static java.net.HttpURLConnection.HTTP_INTERNAL_ERROR;
 import static java.net.HttpURLConnection.HTTP_NOT_FOUND;
 
 // TODO: Auto-generated Javadoc
@@ -49,6 +52,10 @@ abstract class GitHubConnectorResponseErrorHandler {
 
     /** The status http bad request or greater. */
     static GitHubConnectorResponseErrorHandler STATUS_HTTP_BAD_REQUEST_OR_GREATER = new GitHubConnectorResponseErrorHandler() {
+        private static final String CONTENT_TYPE = "Content-type";
+        private static final String TEXT_HTML = "text/html";
+        private static final String UNICORN_TITLE = "<title>Unicorn!";
+
         @Override
         public boolean isError(@NotNull GitHubConnectorResponse connectorResponse) throws IOException {
             return connectorResponse.statusCode() >= HTTP_BAD_REQUEST;
@@ -58,9 +65,37 @@ public boolean isError(@NotNull GitHubConnectorResponse connectorResponse) throw
         public void onError(@NotNull GitHubConnectorResponse connectorResponse) throws IOException {
             if (connectorResponse.statusCode() == HTTP_NOT_FOUND) {
                 throw new FileNotFoundException(connectorResponse.request().url().toString());
+            } else if (isServiceDown(connectorResponse)) {
+                throw new ServiceDownException(connectorResponse);
             } else {
                 throw new HttpException(connectorResponse);
             }
         }
+
+        private boolean isServiceDown(GitHubConnectorResponse connectorResponse) throws IOException {
+            if (connectorResponse.statusCode() < HTTP_INTERNAL_ERROR) {
+                return false;
+            }
+
+            String contentTypeHeader = connectorResponse.header(CONTENT_TYPE);
+            if (contentTypeHeader != null && contentTypeHeader.contains(TEXT_HTML)) {
+                BufferedReader bufReader = new BufferedReader(
+                        new InputStreamReader(connectorResponse.bodyStream()));
+                String line;
+                int hardLineCap = 25;
+                // <title> node is expected in the beginning anyway.
+                // This way we do not load the raw long images' Strings, which are later in the HTML code
+                // Regex or .contains would result in iterating the whole HTML document, if it didn't match
+                // UNICORN_TITLE
+                while (hardLineCap > 0 && (line = bufReader.readLine()) != null) {
+                    if (line.trim().startsWith(UNICORN_TITLE)) {
+                        return true;
+                    }
+                    hardLineCap--;
+                }
+            }
+
+            return false;
+        }
     };
 }

src/main/java/org/kohsuke/github/ServiceDownException.java

@@ -0,0 +1,19 @@
+package org.kohsuke.github;
+
+import org.kohsuke.github.connector.GitHubConnectorResponse;
+
+import java.io.IOException;
+
+/**
+ * Special {@link IOException} case for http exceptions, when {@link HttpException} is thrown due to GitHub service
+ * being down.
+ *
+ * Inherits from {@link HttpException} to maintain compatibility with existing clients.
+ *
+ * @author <a href="mailto:[email protected]">Rastislav Budinsky</a>
+ */
+public class ServiceDownException extends HttpException {
+    public ServiceDownException(GitHubConnectorResponse connectorResponse) {
+        super(connectorResponse);
+    }
+}

src/test/java/org/kohsuke/github/GitHubTest.java

@@ -397,4 +397,20 @@ public void testHeaderFieldName() throws Exception {
                 org.getResponseHeaderFields().keySet().contains("CacHe-ControL"));
         assertThat(org.getResponseHeaderFields().get("cachE-cOntrol").get(0), is("private, max-age=60, s-maxage=60"));
     }
+
+    /**
+     * Test expect GitHub {@link ServiceDownException}
+     *
+     */
+    @Test
+    public void testCatchServiceDownException() {
+        snapshotNotAllowed();
+        try {
+            GHRepository repo = gitHub.getRepository("hub4j-test-org/github-api");
+            repo.getFileContent("ghcontent-ro/service-down");
+            fail("Exception was expected");
+        } catch (IOException e) {
+            assertThat(e.getClass().getName(), equalToIgnoringCase(ServiceDownException.class.getName()));
+        }
+    }
 }

src/test/resources/org/kohsuke/github/GitHubTest/wiremock/testCatchServiceDownException/__files/1-user.json

@@ -0,0 +1,34 @@
+{
+  "login": "The-Huginn",
+  "id": 78657734,
+  "node_id": "MDQ6VXNlcjc4NjU3NzM0",
+  "avatar_url": "https://avatars.githubusercontent.com/u/78657734?v=4",
+  "gravatar_id": "",
+  "url": "https://api.github.com/users/The-Huginn",
+  "html_url": "https://github.com/The-Huginn",
+  "followers_url": "https://api.github.com/users/The-Huginn/followers",
+  "following_url": "https://api.github.com/users/The-Huginn/following{/other_user}",
+  "gists_url": "https://api.github.com/users/The-Huginn/gists{/gist_id}",
+  "starred_url": "https://api.github.com/users/The-Huginn/starred{/owner}{/repo}",
+  "subscriptions_url": "https://api.github.com/users/The-Huginn/subscriptions",
+  "organizations_url": "https://api.github.com/users/The-Huginn/orgs",
+  "repos_url": "https://api.github.com/users/The-Huginn/repos",
+  "events_url": "https://api.github.com/users/The-Huginn/events{/privacy}",
+  "received_events_url": "https://api.github.com/users/The-Huginn/received_events",
+  "type": "User",
+  "site_admin": false,
+  "name": "Rastislav Budinsky",
+  "company": "Red Hat",
+  "blog": "thehuginn.com",
+  "location": null,
+  "email": null,
+  "hireable": null,
+  "bio": null,
+  "twitter_username": "The_Hug1nn",
+  "public_repos": 47,
+  "public_gists": 0,
+  "followers": 3,
+  "following": 2,
+  "created_at": "2021-02-06T17:33:36Z",
+  "updated_at": "2024-03-11T08:56:45Z"
+}