Assert that x-goog-generation is present

Author: nicktindall

modules/repository-gcs/src/main/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageRetryingInputStream.java

@@ -156,8 +156,9 @@ private Long parseGenerationHeader(HttpResponse response) {
                 return Long.parseLong(generationHeader);
             } catch (NumberFormatException e) {
                 assert false : "Unexpected value for x-goog-generation header: " + generationHeader;
-                return null;
             }
+        } else {
+            assert false : "Missing x-goog-generation header";
         }
         return null;
     }

modules/repository-gcs/src/test/java/org/elasticsearch/repositories/gcs/GoogleCloudStorageBlobContainerRetriesTests.java

@@ -19,6 +19,7 @@
 import com.google.cloud.http.HttpTransportOptions;
 import com.google.cloud.storage.StorageException;
 import com.google.cloud.storage.StorageOptions;
+import com.sun.net.httpserver.HttpExchange;
 import com.sun.net.httpserver.HttpHandler;
 
 import org.apache.http.HttpStatus;
@@ -216,6 +217,11 @@ public HttpRequestInitializer getHttpRequestInitializer(ServiceOptions<?, ?> ser
         );
     }
 
+    @Override
+    protected void addSuccessfulDownloadHeaders(HttpExchange exchange) {
+        exchange.getResponseHeaders().add("x-goog-generation", "1");
+    }
+
     public void testShouldRetryOnConnectionRefused() {
         // port 1 should never be open
         endpointUrlOverride = "http://127.0.0.1:1";
@@ -246,6 +252,7 @@ public void testReadLargeBlobWithRetries() throws Exception {
         httpServer.createContext(downloadStorageEndpoint(blobContainer, "large_blob_retries"), exchange -> {
             Streams.readFully(exchange.getRequestBody());
             exchange.getResponseHeaders().add("Content-Type", "application/octet-stream");
+            addSuccessfulDownloadHeaders(exchange);
             final HttpHeaderParser.Range range = getRange(exchange);
             final int offset = Math.toIntExact(range.start());
             final byte[] chunk = Arrays.copyOfRange(bytes, offset, Math.toIntExact(Math.min(range.end() + 1, bytes.length)));

test/fixtures/gcs-fixture/src/main/java/fixture/gcs/GoogleCloudStorageHttpHandler.java

@@ -144,7 +144,7 @@ public void handle(final HttpExchange exchange) throws IOException {
                     // we implement "metageneration", at that point we must incorporate both
                     // See: https://cloud.google.com/storage/docs/metadata#etags
                     exchange.getResponseHeaders().add("ETag", String.valueOf(blob.generation()));
-                    exchange.getResponseHeaders().add("X-Goog-Generation", String.valueOf(blob.generation()));
+                    exchange.getResponseHeaders().add("x-goog-generation", String.valueOf(blob.generation()));
                     exchange.getResponseHeaders().add("Content-Type", "application/octet-stream");
                     exchange.sendResponseHeaders(statusCode, response.length());
                     response.writeTo(exchange.getResponseBody());

test/framework/src/main/java/org/elasticsearch/repositories/blobstore/AbstractBlobContainerRetriesTestCase.java

@@ -73,6 +73,11 @@ public void tearDown() throws Exception {
         super.tearDown();
     }
 
+    /**
+     * Override to add any headers you expect on a successful download
+     */
+    protected void addSuccessfulDownloadHeaders(HttpExchange exchange) {}
+
     protected abstract String downloadStorageEndpoint(BlobContainer container, String blob);
 
     protected abstract String bytesContentType();
@@ -118,6 +123,7 @@ public void testReadBlobWithRetries() throws Exception {
             if (countDown.countDown()) {
                 final int rangeStart = getRangeStart(exchange);
                 assertThat(rangeStart, lessThan(bytes.length));
+                addSuccessfulDownloadHeaders(exchange);
                 exchange.getResponseHeaders().add("Content-Type", bytesContentType());
                 exchange.sendResponseHeaders(HttpStatus.SC_OK, bytes.length - rangeStart);
                 exchange.getResponseBody().write(bytes, rangeStart, bytes.length - rangeStart);
@@ -401,6 +407,7 @@ protected int sendIncompleteContent(HttpExchange exchange, byte[] bytes) throws
             length = bytes.length - rangeStart;
         }
         exchange.getResponseHeaders().add("Content-Type", bytesContentType());
+        addSuccessfulDownloadHeaders(exchange);
         exchange.sendResponseHeaders(HttpStatus.SC_OK, length);
         int minSend = Math.min(0, length - 1);
         final int bytesToSend = randomIntBetween(minSend, length - 1);