Enables implementations of the BlobContainer interface to (#19749)

conform with the requirements of the writeBlob method by
throwing a FileAlreadyExistsException if attempting to write
to a blob that already exists. This change means implementations
of BlobContainer should never overwrite blobs - to overwrite a
blob, it must first be deleted and then can be written again.

Closes #15579

Author: Ali Beyad

core/src/main/java/org/elasticsearch/common/blobstore/BlobContainer.java

@@ -21,6 +21,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.NoSuchFileException;
 import java.util.Map;
 
@@ -68,8 +69,8 @@ public interface BlobContainer {
      * @param   blobSize
      *          The size of the blob to be written, in bytes.  It is implementation dependent whether
      *          this value is used in writing the blob to the repository.
-     * @throws  IOException if the input stream could not be read, a blob by the same name already exists,
-     *          or the target blob could not be written to.
+     * @throws  FileAlreadyExistsException if a blob by the same name already exists
+     * @throws  IOException if the input stream could not be read, or the target blob could not be written to.
      */
     void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException;
 

core/src/main/java/org/elasticsearch/common/blobstore/fs/FsBlobContainer.java

@@ -32,6 +32,7 @@
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.nio.file.DirectoryStream;
+import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.Files;
 import java.nio.file.NoSuchFileException;
 import java.nio.file.Path;
@@ -108,6 +109,9 @@ public InputStream readBlob(String name) throws IOException {
 
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException {
+        if (blobExists(blobName)) {
+            throw new FileAlreadyExistsException("blob [" + blobName + "] already exists, cannot overwrite");
+        }
         final Path file = path.resolve(blobName);
         try (OutputStream outputStream = Files.newOutputStream(file, StandardOpenOption.CREATE_NEW)) {
             Streams.copy(inputStream, outputStream, new byte[blobStore.bufferSizeInBytes()]);

plugins/repository-azure/src/main/java/org/elasticsearch/cloud/azure/blobstore/AzureBlobContainer.java

@@ -34,6 +34,7 @@
 import java.io.OutputStream;
 import java.net.HttpURLConnection;
 import java.net.URISyntaxException;
+import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.NoSuchFileException;
 import java.util.Map;
 
@@ -84,6 +85,9 @@ public InputStream readBlob(String blobName) throws IOException {
 
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException {
+        if (blobExists(blobName)) {
+            throw new FileAlreadyExistsException("blob [" + blobName + "] already exists, cannot overwrite");
+        }
         logger.trace("writeBlob({}, stream, {})", blobName, blobSize);
         try (OutputStream stream = createOutput(blobName)) {
             Streams.copy(inputStream, stream);

plugins/repository-gcs/src/main/java/org/elasticsearch/common/blobstore/gcs/GoogleCloudStorageBlobContainer.java

@@ -26,6 +26,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.FileAlreadyExistsException;
 import java.util.Map;
 
 public class GoogleCloudStorageBlobContainer extends AbstractBlobContainer {
@@ -65,6 +66,9 @@ public InputStream readBlob(String blobName) throws IOException {
 
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException {
+        if (blobExists(blobName)) {
+            throw new FileAlreadyExistsException("blob [" + blobName + "] already exists, cannot overwrite");
+        }
         blobStore.writeBlob(buildKey(blobName), inputStream, blobSize);
     }
 

plugins/repository-hdfs/src/main/java/org/elasticsearch/repositories/hdfs/HdfsBlobContainer.java

@@ -34,6 +34,7 @@
 
 import java.io.IOException;
 import java.io.InputStream;
+import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.NoSuchFileException;
 import java.util.Collections;
 import java.util.EnumSet;
@@ -107,6 +108,9 @@ public InputStream run(FileContext fileContext) throws IOException {
 
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException {
+        if (blobExists(blobName)) {
+            throw new FileAlreadyExistsException("blob [" + blobName + "] already exists, cannot overwrite");
+        }
         store.execute(new Operation<Void>() {
             @Override
             public Void run(FileContext fileContext) throws IOException {

plugins/repository-s3/src/main/java/org/elasticsearch/cloud/aws/blobstore/S3BlobContainer.java

@@ -39,6 +39,7 @@
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
+import java.nio.file.FileAlreadyExistsException;
 import java.nio.file.NoSuchFileException;
 import java.security.AccessController;
 import java.security.PrivilegedActionException;
@@ -100,6 +101,9 @@ public InputStream readBlob(String blobName) throws IOException {
 
     @Override
     public void writeBlob(String blobName, InputStream inputStream, long blobSize) throws IOException {
+        if (blobExists(blobName)) {
+            throw new FileAlreadyExistsException("blob [" + blobName + "] already exists, cannot overwrite");
+        }
         try (OutputStream stream = createOutput(blobName)) {
             Streams.copy(inputStream, stream);
         }

test/framework/src/main/java/org/elasticsearch/repositories/ESBlobStoreContainerTestCase.java

@@ -128,7 +128,6 @@ public void testDeleteBlob() throws IOException {
         }
     }
 
-    @AwaitsFix(bugUrl = "https://github.com/elastic/elasticsearch/issues/15579")
     public void testVerifyOverwriteFails() throws IOException {
         try (final BlobStore store = newBlobStore()) {
             final String blobName = "foobar";