TD 4 - Cloud and Edge Infrastructures : AWS Lambda

  <dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>aws-lambda-java-core</artifactId>
    <version>1.2.3</version>
  </dependency>
  <dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>aws-lambda-java-events</artifactId>
    <version>3.11.3</version>
  </dependency>
  <dependency>
    <groupId>com.amazonaws</groupId>
    <artifactId>aws-java-sdk-s3</artifactId>
  </dependency>

<plugin>
  <groupId>org.apache.maven.plugins</groupId>
  <artifactId>maven-shade-plugin</artifactId>
  <version>3.5.1</version>
  <configuration>
    <createDependencyReducedPom>false</createDependencyReducedPom>
  </configuration>
  <executions>
    <execution>
      <phase>package</phase>
      <goals>
        <goal>shade</goal>
      </goals>
    </execution>
  </executions>
</plugin>

package fr.emse.lambda;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;

import com.amazonaws.services.lambda.runtime.Context;
import com.amazonaws.services.lambda.runtime.RequestHandler;
import com.amazonaws.services.lambda.runtime.events.S3Event;
import com.amazonaws.services.lambda.runtime.events.models.s3.S3EventNotification.S3EventNotificationRecord;
import com.amazonaws.services.s3.AmazonS3;
import com.amazonaws.services.s3.AmazonS3ClientBuilder;
import com.amazonaws.services.s3.model.S3Object;

public class MyLambdaFunction implements RequestHandler<S3Event, String> {

  public String handleRequest(S3Event event, Context context) {
    S3EventNotificationRecord record = event.getRecords().get(0);
    String bucketName = record.getS3().getBucket().getName();
    String fileKey = record.getS3().getObject().getUrlDecodedKey();

    AmazonS3 s3Client = AmazonS3ClientBuilder.defaultClient();
    try (final S3Object s3Object = s3Client.getObject(bucketName, fileKey);
        final InputStreamReader streamReader = new InputStreamReader(s3Object.getObjectContent(),
            StandardCharsets.UTF_8);
        final BufferedReader reader = new BufferedReader(streamReader)) {

      Integer[] values = new Integer[4];
      values[0] = 0; // total
      values[1] = 0; // count
      values[2] = Integer.MAX_VALUE; // min
      values[3] = Integer.MIN_VALUE; // max

      reader.lines().forEach(line -> {
        int value = Integer.parseInt(line);
        values[0] += value;
        values[1] += 1;
        if (values[2] > value) {
          values[2] = value;
        }
        if (values[3] < value) {
          values[3] = value;
        }
      });

      System.out.println("Count: " + values[1] + " Sum: " + values[0] + " Avg: " + values[0] / (double) values[1]
          + " Min: " + values[2] + " Max: " + values[3]);
    } catch (final IOException e) {
      System.out.println("IOException: " + e.getMessage());
    }

    System.out.println("Finished... processing file");
    return "Ok";
  }
}