MongoDBBatchSource.java

/*
 * Copyright © 2019 Cask Data, Inc.
 *
 * 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 io.cdap.plugin.batch.source;

import com.google.common.base.Strings;
import com.google.common.collect.ImmutableSet;
import com.mongodb.client.model.Projections;
import com.mongodb.hadoop.MongoInputFormat;
import com.mongodb.hadoop.util.MongoConfigUtil;
import io.cdap.cdap.api.annotation.Description;
import io.cdap.cdap.api.annotation.Macro;
import io.cdap.cdap.api.annotation.Name;
import io.cdap.cdap.api.annotation.Plugin;
import io.cdap.cdap.api.data.batch.Input;
import io.cdap.cdap.api.data.format.StructuredRecord;
import io.cdap.cdap.api.data.schema.Schema;
import io.cdap.cdap.api.dataset.lib.KeyValue;
import io.cdap.cdap.etl.api.Emitter;
import io.cdap.cdap.etl.api.InvalidEntry;
import io.cdap.cdap.etl.api.PipelineConfigurer;
import io.cdap.cdap.etl.api.batch.BatchRuntimeContext;
import io.cdap.cdap.etl.api.batch.BatchSource;
import io.cdap.cdap.etl.api.batch.BatchSourceContext;
import io.cdap.cdap.etl.api.validation.InvalidConfigPropertyException;
import io.cdap.plugin.ErrorHandling;
import io.cdap.plugin.MongoDBConfig;
import io.cdap.plugin.MongoDBConstants;
import io.cdap.plugin.common.LineageRecorder;
import io.cdap.plugin.common.ReferenceBatchSource;
import io.cdap.plugin.common.ReferencePluginConfig;
import io.cdap.plugin.common.SourceInputFormatProvider;
import org.apache.hadoop.conf.Configuration;
import org.bson.BSONObject;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.util.List;
import java.util.Objects;
import java.util.Set;
import java.util.stream.Collectors;
import javax.annotation.Nullable;

/**
 * A {@link BatchSource} that reads data from MongoDB and converts each document into
 * a {@link StructuredRecord} using the specified Schema.
 */
@Plugin(type = BatchSource.PLUGIN_TYPE)
@Name(MongoDBConstants.PLUGIN_NAME)
@Description("MongoDB Batch Source will read documents from MongoDB and convert each document " +
  "into a StructuredRecord with the help of the specified Schema. ")
public class MongoDBBatchSource extends ReferenceBatchSource<Object, BSONObject, StructuredRecord> {

  private static final Logger LOG = LoggerFactory.getLogger(MongoDBBatchSource.class);
  private final MongoDBSourceConfig config;
  private BSONObjectToRecordTransformer bsonObjectToRecordTransformer;

  public MongoDBBatchSource(MongoDBSourceConfig config) {
    super(new ReferencePluginConfig(config.getReferenceName()));
    this.config = config;
  }

  @Override
  public void configurePipeline(PipelineConfigurer pipelineConfigurer) {
    super.configurePipeline(pipelineConfigurer);
    config.validate();
    Schema schema = config.getParsedSchema();
    pipelineConfigurer.getStageConfigurer().setOutputSchema(schema);
    pipelineConfigurer.getStageConfigurer().setErrorSchema(MongoDBSourceConfig.ERROR_SCHEMA);
  }

  @Override
  public void prepareRun(BatchSourceContext context) throws Exception {
    config.validate();
    Configuration conf = new Configuration();
    conf.clear();

    MongoConfigUtil.setInputFormat(conf, MongoInputFormat.class);
    MongoConfigUtil.setInputURI(conf, config.getConnectionString());
    MongoConfigUtil.setFields(conf, config.getProjectionDocument());
    if (!Strings.isNullOrEmpty(config.inputQuery)) {
      MongoConfigUtil.setQuery(conf, config.inputQuery);
    }
    if (!Strings.isNullOrEmpty(config.authConnectionString)) {
      MongoConfigUtil.setAuthURI(conf, config.authConnectionString);
    }

    MongoConfigUtil.setRangeQueryEnabled(conf, true);

    emitLineage(context);
    context.setInput(Input.of(config.getReferenceName(),
                              new SourceInputFormatProvider(MongoConfigUtil.getInputFormat(conf), conf)));
  }

  @Override
  public void initialize(BatchRuntimeContext context) throws Exception {
    super.initialize(context);
    bsonObjectToRecordTransformer = new BSONObjectToRecordTransformer(config.getParsedSchema());
  }

  @Override
  public void transform(KeyValue<Object, BSONObject> input, Emitter<StructuredRecord> emitter) throws Exception {
    BSONObject bsonObject = input.getValue();
    try {
      emitter.emit(bsonObjectToRecordTransformer.transform(bsonObject));
    } catch (Exception e) {
      switch (config.getErrorHandling()) {
        case SEND_TO_ERROR:
          StructuredRecord errorRecord = StructuredRecord.builder(MongoDBSourceConfig.ERROR_SCHEMA)
            .set("document", bsonObject.toString())
            .build();
          emitter.emitError(new InvalidEntry<>(400, e.getMessage(), errorRecord));
          break;
        case SKIP:
          LOG.warn("Failed to process record, skipping it", e);
          break;
        case FAIL_PIPELINE:
          throw new RuntimeException("Failed to process record", e);
        default:
          // this should never happen because it is validated at configure and prepare time
          throw new IllegalStateException(String.format("Unknown error handling strategy '%s'",
                                                        config.getErrorHandling()));
      }
    }
  }

  private void emitLineage(BatchSourceContext context) {
    LineageRecorder lineageRecorder = new LineageRecorder(context, config.getReferenceName());
    lineageRecorder.createExternalDataset(config.getParsedSchema());
    List<Schema.Field> fields = Objects.requireNonNull(config.getParsedSchema()).getFields();
    if (fields != null && !fields.isEmpty()) {
      lineageRecorder.recordRead("Read",
                                 String.format("Read from '%s' MongoDB collection.", config.getCollection()),
                                 fields.stream().map(Schema.Field::getName).collect(Collectors.toList()));
    }
  }

  /**
   * Config class for {@link MongoDBBatchSource}.
   */
  public static class MongoDBSourceConfig extends MongoDBConfig {

    public static final Schema ERROR_SCHEMA = Schema.recordOf("error", Schema.Field.of("document",
                                                                                       Schema.of(Schema.Type.STRING)));

    public static final Set<Schema.Type> SUPPORTED_SIMPLE_TYPES = ImmutableSet.of(Schema.Type.BOOLEAN, Schema.Type.INT,
                                                                                  Schema.Type.DOUBLE, Schema.Type.BYTES,
                                                                                  Schema.Type.LONG, Schema.Type.STRING,
                                                                                  Schema.Type.ARRAY, Schema.Type.RECORD,
                                                                                  Schema.Type.MAP);

    public static final Set<Schema.LogicalType> SUPPORTED_LOGICAL_TYPES = ImmutableSet.of(
      Schema.LogicalType.DECIMAL, Schema.LogicalType.TIMESTAMP_MILLIS, Schema.LogicalType.TIMESTAMP_MICROS);

    @Name(MongoDBConstants.SCHEMA)
    @Description("Schema of records output by the source.")
    private String schema;

    @Name(MongoDBConstants.INPUT_QUERY)
    @Description("Optionally filter the input collection with a query. This query must be represented in JSON " +
      "format, and use the MongoDB extended JSON format to represent non-native JSON data types.")
    @Nullable
    @Macro
    private String inputQuery;

    @Name(MongoDBConstants.ON_ERROR)
    @Description("Specifies how to handle error in record processing. Error will be thrown if failed to parse value " +
      "according to provided schema.")
    @Macro
    private String onError;

    @Name(MongoDBConstants.AUTH_CONNECTION_STRING)
    @Nullable
    @Description("Auxiliary MongoDB connection string to authenticate against when constructing splits.")
    @Macro
    private String authConnectionString;

    public MongoDBSourceConfig(String referenceName, String host, int port, String database, String collection,
                               String user, String password, boolean connectUsingSRVString,
                               String connectionArguments, String schema,
                               String inputQuery, String onError, String authConnectionString) {
      super(referenceName, host, port, database, collection, user, password,
            connectUsingSRVString, connectionArguments);
      this.schema = schema;
      this.inputQuery = inputQuery;
      this.onError = onError;
      this.authConnectionString = authConnectionString;
    }

    public String getSchema() {
      return schema;
    }

    @Nullable
    public String getInputQuery() {
      return inputQuery;
    }

    public String getOnError() {
      return onError;
    }

    @Nullable
    public String getAuthConnectionString() {
      return authConnectionString;
    }

    public Schema getParsedSchema() {
      try {
        return Schema.parseJson(schema);
      } catch (IOException e) {
        throw new InvalidConfigPropertyException("Invalid schema", e, MongoDBConstants.SCHEMA);
      }
    }

    /**
     * Constructs JSON projection document based on the output schema.
     *
     * @return JSON projection document.
     */
    public String getProjectionDocument() {
      List<String> fieldNames = getParsedSchema().getFields().stream()
        .map(Schema.Field::getName)
        .collect(Collectors.toList());

      return Projections.include(fieldNames).toString();
    }

    public ErrorHandling getErrorHandling() {
      return Objects.requireNonNull(ErrorHandling.fromDisplayName(onError));
    }

    @Override
    public void validate() {
      super.validate();
      if (!containsMacro(MongoDBConstants.ON_ERROR)) {
        if (Strings.isNullOrEmpty(onError)) {
          throw new InvalidConfigPropertyException("Error handling must be specified", MongoDBConstants.ON_ERROR);
        }
        if (ErrorHandling.fromDisplayName(onError) == null) {
          throw new InvalidConfigPropertyException("Invalid record error handling strategy name",
                                                   MongoDBConstants.ON_ERROR);
        }
      }
      if (!containsMacro(MongoDBConstants.SCHEMA)) {
        if (schema == null) {
          throw new InvalidConfigPropertyException("Schema must be specified", MongoDBConstants.SCHEMA);
        }
        Schema parsedSchema = getParsedSchema();
        try {
          super.validateSchema(parsedSchema, SUPPORTED_LOGICAL_TYPES, SUPPORTED_SIMPLE_TYPES);
        } catch (IllegalArgumentException e) {
          throw new InvalidConfigPropertyException(e.getMessage(), e, MongoDBConstants.SCHEMA);
        }
      }
    }
  }
}