feat(dataflow): Dataflow to Apache Iceberg with dynamic destinations (GoogleCloudPlatform#9645)

* docs(sample): Dataflow to Apache Iceberg with dynamic destinations

* Fix linter errors

* Bump Apache Beam version

* Update copyright year

* Address PR review feedback

* Add code comments

Author: VeronicaWasson

dataflow/snippets/pom.xml

@@ -37,7 +37,7 @@
     <maven.compiler.source>11</maven.compiler.source>
     <maven.compiler.target>11</maven.compiler.target>
     <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
-    <apache_beam.version>2.63.0</apache_beam.version>
+    <apache_beam.version>2.62.0</apache_beam.version>
     <slf4j.version>2.0.12</slf4j.version>
     <parquet.version>1.14.0</parquet.version>
     <iceberg.version>1.4.2</iceberg.version>

dataflow/snippets/src/main/java/com/example/dataflow/ApacheIcebergDynamicDestinations.java

@@ -0,0 +1,100 @@
+/*
+ * Copyright 2025 Google LLC
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.dataflow;
+
+// [START dataflow_apache_iceberg_dynamic_destinations]
+import com.google.common.collect.ImmutableMap;
+import java.util.Arrays;
+import java.util.List;
+import java.util.Map;
+import org.apache.beam.sdk.Pipeline;
+import org.apache.beam.sdk.PipelineResult;
+import org.apache.beam.sdk.managed.Managed;
+import org.apache.beam.sdk.options.Description;
+import org.apache.beam.sdk.options.PipelineOptions;
+import org.apache.beam.sdk.options.PipelineOptionsFactory;
+import org.apache.beam.sdk.schemas.Schema;
+import org.apache.beam.sdk.transforms.Create;
+import org.apache.beam.sdk.transforms.JsonToRow;
+
+public class ApacheIcebergDynamicDestinations {
+
+  // The schema for the table rows.
+  public static final Schema SCHEMA = new Schema.Builder()
+      .addInt64Field("id")
+      .addStringField("name")
+      .addStringField("airport")
+      .build();
+
+  // The data to write to table, formatted as JSON strings.
+  static final List<String> TABLE_ROWS = List.of(
+      "{\"id\":0, \"name\":\"Alice\", \"airport\": \"ORD\" }",
+      "{\"id\":1, \"name\":\"Bob\", \"airport\": \"SYD\" }",
+      "{\"id\":2, \"name\":\"Charles\", \"airport\": \"ORD\" }"
+  );
+
+  public interface Options extends PipelineOptions {
+    @Description("The URI of the Apache Iceberg warehouse location")
+    String getWarehouseLocation();
+
+    void setWarehouseLocation(String value);
+
+    @Description("The name of the Apache Iceberg catalog")
+    String getCatalogName();
+
+    void setCatalogName(String value);
+  }
+
+  // Write JSON data to Apache Iceberg, using dynamic destinations to determine the Iceberg table
+  // where Dataflow writes each record. The JSON data contains a field named "airport". The
+  // Dataflow pipeline writes to Iceberg tables with the naming pattern "flights-{airport}".
+  public static void main(String[] args) {
+    // Parse the pipeline options passed into the application. Example:
+    //   --runner=DirectRunner --warehouseLocation=$LOCATION --catalogName=$CATALOG \
+    // For more information, see https://beam.apache.org/documentation/programming-guide/#configuring-pipeline-options
+    Options options = PipelineOptionsFactory.fromArgs(args).withValidation().as(Options.class);
+    Pipeline pipeline = Pipeline.create(options);
+
+    // Configure the Iceberg source I/O
+    Map catalogConfig = ImmutableMap.<String, Object>builder()
+        .put("warehouse", options.getWarehouseLocation())
+        .put("type", "hadoop")
+        .build();
+
+    ImmutableMap<String, Object> config = ImmutableMap.<String, Object>builder()
+        .put("catalog_name", options.getCatalogName())
+        .put("catalog_properties", catalogConfig)
+        // Route the incoming records based on the value of the "airport" field.
+        .put("table", "flights-{airport}")
+        // Specify which fields to keep from the input data.
+        .put("keep", Arrays.asList("name", "id"))
+        .build();
+
+    // Build the pipeline.
+    pipeline
+        // Read in-memory JSON data.
+        .apply(Create.of(TABLE_ROWS))
+        // Convert the JSON records to Row objects.
+        .apply(JsonToRow.withSchema(SCHEMA))
+        // Write each Row to Apache Iceberg.
+        .apply(Managed.write(Managed.ICEBERG).withConfig(config));
+
+    // Run the pipeline.
+    pipeline.run().waitUntilFinish();
+  }
+}
+// [END dataflow_apache_iceberg_dynamic_destinations]

dataflow/snippets/src/test/java/com/example/dataflow/ApacheIcebergIT.java

@@ -16,15 +16,15 @@
 
 package com.example.dataflow;
 
+import static org.junit.Assert.assertEquals;
 import static org.junit.Assert.assertTrue;
 
 import com.google.common.collect.ImmutableMap;
-import java.io.ByteArrayOutputStream;
 import java.io.IOException;
-import java.io.PrintStream;
 import java.nio.file.Files;
 import java.nio.file.Paths;
 import java.util.UUID;
+import org.apache.beam.sdk.PipelineResult;
 import org.apache.hadoop.conf.Configuration;
 import org.apache.hadoop.fs.Path;
 import org.apache.iceberg.CatalogProperties;
@@ -52,25 +52,19 @@
 import org.junit.Test;
 
 public class ApacheIcebergIT {
-  private ByteArrayOutputStream bout;
-  private final PrintStream originalOut = System.out;
-
-  private static final String CATALOG_NAME = "local";
-  private static final String TABLE_NAME = "table1";
-  private static final TableIdentifier TABLE_IDENTIFIER = TableIdentifier.of(TABLE_NAME);
-
-  // The output file that the Dataflow pipeline writes.
-  private static final String OUTPUT_FILE_NAME_PREFIX = UUID.randomUUID().toString();
-  private static final String OUTPUT_FILE_NAME = OUTPUT_FILE_NAME_PREFIX + "-00000-of-00001.txt";
 
   private Configuration hadoopConf = new Configuration();
   private java.nio.file.Path warehouseDirectory;
   private String warehouseLocation;
   private Catalog catalog;
-  private Table table;
+  private static final String CATALOG_NAME = "local";
 
+  String outputFileNamePrefix = UUID.randomUUID().toString();
+  String outputFileName = outputFileNamePrefix + "-00000-of-00001.txt";
 
-  private void createIcebergTable(Catalog catalog, TableIdentifier tableId) {
+  private Table createIcebergTable(String name) {
+
+    TableIdentifier tableId = TableIdentifier.of(name);
 
     // This schema represents an Iceberg table schema. It needs to match the
     // org.apache.beam.sdk.schemas.Schema that is defined in ApacheIcebergWrite. However, these
@@ -79,10 +73,10 @@ private void createIcebergTable(Catalog catalog, TableIdentifier tableId) {
         NestedField.required(1, "id", Types.LongType.get()),
         NestedField.optional(2, "name", Types.StringType.get()));
 
-    table = catalog.createTable(tableId, schema);
+    return catalog.createTable(tableId, schema);
   }
 
-  private void writeTableRecord()
+  private void writeTableRecord(Table table)
       throws IOException {
     GenericRecord record = GenericRecord.create(table.schema());
     record.setField("id", 0L);
@@ -109,72 +103,94 @@ private void writeTableRecord()
         .commit();
   }
 
+  private boolean tableContainsRecord(Table table, String data) {
+    CloseableIterable<Record> records = IcebergGenerics.read(table).build();
+    for (Record r : records) {
+      if (r.toString().contains(data)) {
+        return true;
+      }
+    }
+    return false;
+  }
+
   @Before
   public void setUp() throws IOException {
-    bout = new ByteArrayOutputStream();
-    System.setOut(new PrintStream(bout));
-
     // Create an Apache Iceberg catalog with a table.
     warehouseDirectory = Files.createTempDirectory("test-warehouse");
     warehouseLocation = "file:" + warehouseDirectory.toString();
-    System.out.println(warehouseLocation);
     catalog =
         CatalogUtil.loadCatalog(
             CatalogUtil.ICEBERG_CATALOG_HADOOP,
             CATALOG_NAME,
             ImmutableMap.of(CatalogProperties.WAREHOUSE_LOCATION, warehouseLocation),
             hadoopConf);
-    createIcebergTable(catalog, TABLE_IDENTIFIER);
+
   }
 
   @After
   public void tearDown() throws IOException {
-    Files.deleteIfExists(Paths.get(OUTPUT_FILE_NAME));
-    System.setOut(originalOut);
+    Files.deleteIfExists(Paths.get(outputFileName));
   }
 
   @Test
   public void testApacheIcebergWrite() {
+    String tableName = "write_table";
+    final Table table = createIcebergTable("write_table");
+
     // Run the Dataflow pipeline.
     ApacheIcebergWrite.main(
         new String[] {
             "--runner=DirectRunner",
             "--warehouseLocation=" + warehouseLocation,
             "--catalogName=" + CATALOG_NAME,
-            "--tableName=" + TABLE_NAME
+            "--tableName=" + tableName
         });
 
     // Verify that the pipeline wrote records to the table.
-    Table table = catalog.loadTable(TABLE_IDENTIFIER);
-    CloseableIterable<Record> records = IcebergGenerics.read(table)
-        .build();
-    for (Record r : records) {
-      System.out.println(r);
-    }
+    assertTrue(tableContainsRecord(table, "0, Alice"));
+    assertTrue(tableContainsRecord(table, "1, Bob"));
+    assertTrue(tableContainsRecord(table, "2, Charles"));
+  }
+
+  @Test
+  public void testApacheIcebergDynamicDestinations() {
+    final Table tableORD = createIcebergTable("flights-ORD");
+    final Table tableSYD = createIcebergTable("flights-SYD");
+
+    // Run the Dataflow pipeline.
+    ApacheIcebergDynamicDestinations.main(
+        new String[] {
+            "--runner=DirectRunner",
+            "--warehouseLocation=" + warehouseLocation,
+            "--catalogName=" + CATALOG_NAME
+        });
 
-    String got = bout.toString();
-    assertTrue(got.contains("0, Alice"));
-    assertTrue(got.contains("1, Bob"));
-    assertTrue(got.contains("2, Charles"));
+    // Verify that the pipeline wrote records to the correct tables.
+    assertTrue(tableContainsRecord(tableORD, "0, Alice"));
+    assertTrue(tableContainsRecord(tableORD, "2, Charles"));
+    assertTrue(tableContainsRecord(tableSYD, "1, Bob"));
   }
 
   @Test
   public void testApacheIcebergRead() throws IOException {
+    String tableName = "read_table";
+    final Table table = createIcebergTable(tableName);
+
     // Seed the Apache Iceberg table with data.
-    writeTableRecord();
+    writeTableRecord(table);
 
     // Run the Dataflow pipeline.
     ApacheIcebergRead.main(
         new String[] {
             "--runner=DirectRunner",
             "--warehouseLocation=" + warehouseLocation,
             "--catalogName=" + CATALOG_NAME,
-            "--tableName=" + TABLE_NAME,
-            "--outputPath=" + OUTPUT_FILE_NAME_PREFIX
+            "--tableName=" + tableName,
+            "--outputPath=" + outputFileNamePrefix
         });
 
-    // Verify the pipeline wrote the table data to a local file.
-    String output = Files.readString(Paths.get(OUTPUT_FILE_NAME));
+    // Verify the pipeline wrote the table data to a text file.
+    String output = Files.readString(Paths.get(outputFileName));
     assertTrue(output.contains("0:Person-0"));
   }
-}
+}