Added replaceGcsFilesWithLocalFiles (apache#33006)

* Added replaceGcsFilesWithLocalFiles

* use static

* added unit tests

* make it public

* Added logs

* spotless

* Added a simple IT to cover downloading the GCS file and staging it later.

it/google-cloud-platform/src/test/java/org/apache/beam/it/gcp/WordCountIT.java

@@ -19,15 +19,19 @@
 
 import static org.apache.beam.it.truthmatchers.PipelineAsserts.assertThatPipeline;
 import static org.apache.beam.it.truthmatchers.PipelineAsserts.assertThatResult;
+import static org.apache.beam.sdk.util.construction.resources.PipelineResources.detectClassPathResourcesToStage;
 
 import java.io.IOException;
 import java.time.Duration;
 import java.util.Arrays;
+import java.util.List;
 import org.apache.beam.it.common.PipelineLauncher.LaunchConfig;
 import org.apache.beam.it.common.PipelineLauncher.LaunchInfo;
 import org.apache.beam.it.common.PipelineLauncher.Sdk;
 import org.apache.beam.it.common.PipelineOperator.Result;
+import org.apache.beam.runners.dataflow.DataflowRunner;
 import org.apache.beam.sdk.io.TextIO;
+import org.apache.beam.sdk.options.PipelineOptions;
 import org.apache.beam.sdk.testing.TestPipeline;
 import org.apache.beam.sdk.transforms.Count;
 import org.apache.beam.sdk.transforms.Filter;
@@ -67,6 +71,29 @@ public void testWordCountDataflow() throws IOException {
     assertThatResult(result).isLaunchFinished();
   }
 
+  @Test
+  public void testWordCountDataflowWithGCSFilesToStage() throws IOException {
+
+    PipelineOptions pipelineOptions = wcPipeline.getOptions();
+    List<String> filesToStage =
+        detectClassPathResourcesToStage(DataflowRunner.class.getClassLoader(), pipelineOptions);
+    filesToStage.add("gs://apache-beam-samples/shakespeare/kinglear.txt");
+
+    LaunchConfig options =
+        LaunchConfig.builder("test-wordcount")
+            .setSdk(Sdk.JAVA)
+            .setPipeline(wcPipeline)
+            .addParameter("runner", "DataflowRunner")
+            .addParameter("filesToStage", String.join(",", filesToStage))
+            .build();
+
+    LaunchInfo launchInfo = pipelineLauncher.launch(project, region, options);
+    assertThatPipeline(launchInfo).isRunning();
+    Result result =
+        pipelineOperator.waitUntilDone(createConfig(launchInfo, Duration.ofMinutes(20)));
+    assertThatResult(result).isLaunchFinished();
+  }
+
   /** Build WordCount pipeline. */
   private void buildPipeline() {
     wcPipeline

runners/google-cloud-dataflow-java/src/main/java/org/apache/beam/runners/dataflow/DataflowRunner.java

@@ -41,10 +41,12 @@
 import com.google.auto.value.AutoValue;
 import java.io.BufferedWriter;
 import java.io.File;
+import java.io.FileOutputStream;
 import java.io.IOException;
 import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.channels.Channels;
+import java.nio.channels.ReadableByteChannel;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.Collections;
@@ -179,6 +181,7 @@
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.Maps;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.hash.HashCode;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.hash.Hashing;
+import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.io.ByteStreams;
 import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.io.Files;
 import org.joda.time.DateTimeUtils;
 import org.joda.time.DateTimeZone;
@@ -257,6 +260,92 @@ public class DataflowRunner extends PipelineRunner<DataflowPipelineJob> {
   /** Dataflow service endpoints are expected to match this pattern. */
   static final String ENDPOINT_REGEXP = "https://[\\S]*googleapis\\.com[/]?";
 
+  /**
+   * Replaces GCS file paths with local file paths by downloading the GCS files locally. This is
+   * useful when files need to be accessed locally before being staged to Dataflow.
+   *
+   * @param filesToStage List of file paths that may contain GCS paths (gs://) and local paths
+   * @return List of local file paths where any GCS paths have been downloaded locally
+   * @throws RuntimeException if there are errors copying GCS files locally
+   */
+  public static List<String> replaceGcsFilesWithLocalFiles(List<String> filesToStage) {
+    List<String> processedFiles = new ArrayList<>();
+
+    for (String fileToStage : filesToStage) {
+      String localPath;
+      if (fileToStage.contains("=")) {
+        // Handle files with staging name specified
+        String[] components = fileToStage.split("=", 2);
+        String stagingName = components[0];
+        String filePath = components[1];
+
+        if (filePath.startsWith("gs://")) {
+          try {
+            // Create temp file with exact same name as GCS file
+            String gcsFileName = filePath.substring(filePath.lastIndexOf('/') + 1);
+            File tempDir = Files.createTempDir();
+            tempDir.deleteOnExit();
+            File tempFile = new File(tempDir, gcsFileName);
+            tempFile.deleteOnExit();
+
+            LOG.info(
+                "Downloading GCS file {} to local temp file {}",
+                filePath,
+                tempFile.getAbsolutePath());
+
+            // Copy GCS file to local temp file
+            ResourceId source = FileSystems.matchNewResource(filePath, false);
+            try (ReadableByteChannel reader = FileSystems.open(source);
+                FileOutputStream writer = new FileOutputStream(tempFile)) {
+              ByteStreams.copy(Channels.newInputStream(reader), writer);
+            }
+
+            localPath = stagingName + "=" + tempFile.getAbsolutePath();
+            LOG.info("Replaced GCS path {} with local path {}", fileToStage, localPath);
+          } catch (IOException e) {
+            throw new RuntimeException("Failed to copy GCS file locally: " + filePath, e);
+          }
+        } else {
+          localPath = fileToStage;
+        }
+      } else {
+        // Handle files without staging name
+        if (fileToStage.startsWith("gs://")) {
+          try {
+            // Create temp file with exact same name as GCS file
+            String gcsFileName = fileToStage.substring(fileToStage.lastIndexOf('/') + 1);
+            File tempDir = Files.createTempDir();
+            tempDir.deleteOnExit();
+            File tempFile = new File(tempDir, gcsFileName);
+            tempFile.deleteOnExit();
+
+            LOG.info(
+                "Downloading GCS file {} to local temp file {}",
+                fileToStage,
+                tempFile.getAbsolutePath());
+
+            // Copy GCS file to local temp file
+            ResourceId source = FileSystems.matchNewResource(fileToStage, false);
+            try (ReadableByteChannel reader = FileSystems.open(source);
+                FileOutputStream writer = new FileOutputStream(tempFile)) {
+              ByteStreams.copy(Channels.newInputStream(reader), writer);
+            }
+
+            localPath = tempFile.getAbsolutePath();
+            LOG.info("Replaced GCS path {} with local path {}", fileToStage, localPath);
+          } catch (IOException e) {
+            throw new RuntimeException("Failed to copy GCS file locally: " + fileToStage, e);
+          }
+        } else {
+          localPath = fileToStage;
+        }
+      }
+      processedFiles.add(localPath);
+    }
+
+    return processedFiles;
+  }
+
   /**
    * Construct a runner from the provided options.
    *
@@ -312,6 +401,9 @@ && isServiceEndpoint(dataflowOptions.getDataflowEndpoint())) {
     }
 
     if (dataflowOptions.getFilesToStage() != null) {
+      // Replace GCS file paths with local file paths
+      dataflowOptions.setFilesToStage(
+          replaceGcsFilesWithLocalFiles(dataflowOptions.getFilesToStage()));
       // The user specifically requested these files, so fail now if they do not exist.
       // (automatically detected classpath elements are permitted to not exist, so later
       // staging will not fail on nonexistent files)

runners/google-cloud-dataflow-java/src/test/java/org/apache/beam/runners/dataflow/DataflowRunnerTest.java

@@ -77,6 +77,7 @@
 import java.io.FileNotFoundException;
 import java.io.IOException;
 import java.io.Serializable;
+import java.io.Writer;
 import java.nio.channels.FileChannel;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
@@ -1155,6 +1156,19 @@ public void testNonExistentStagingLocation() throws IOException {
     assertValidJob(jobCaptor.getValue());
   }
 
+  @Test
+  public void testReplaceGcsFilesWithLocalFilesEmptyList() {
+    List<String> filesToStage = Collections.emptyList();
+    List<String> processedFiles = DataflowRunner.replaceGcsFilesWithLocalFiles(filesToStage);
+    assertTrue(processedFiles.isEmpty());
+  }
+
+  @Test(expected = RuntimeException.class)
+  public void testReplaceGcsFilesWithLocalFilesIOError() {
+    List<String> filesToStage = Collections.singletonList("gs://non-existent-bucket/file.jar");
+    DataflowRunner.replaceGcsFilesWithLocalFiles(filesToStage);
+  }
+
   @Test
   public void testNonExistentProfileLocation() throws IOException {
     DataflowPipelineOptions options = buildPipelineOptions();