サーバーレス アーキテクチャにおける Java 関数のスケーラビリティと弾力性

import com.google.cloud.functions.Context;
import com.google.cloud.functions.RawBackgroundFunction;
import com.google.cloud.storage.Blob;
import com.google.cloud.storage.BlobId;
import com.google.cloud.storage.BlobInfo;
import com.google.cloud.storage.Storage;
import com.google.cloud.storage.StorageOptions;
import java.io.IOException;
import java.io.InputStream;
import java.nio.file.Files;
import java.nio.file.Paths;

public class ThumbnailGenerator implements RawBackgroundFunction {
  private static final String BUCKET_NAME = "my-bucket";
  private static final String THUMBNAIL_SIZE = "50,50";

  @Override
  public void accept(InputStream inputStream, Context context) throws IOException {
    String body = new String(inputStream.readAllBytes(), com.google.api.client.util.Charsets.UTF_8);
    BlobInfo blobInfo = BlobInfo.newBuilder(BlobId.of(BUCKET_NAME, body)).build();

    Storage storage = StorageOptions.getDefaultInstance().getService();
    Blob blob = storage.get(blobInfo);

    if (blob != null) {
      // 生成缩略图
      String thumbFileName = "thumb_" + blob.getName();
      BlobInfo thumbBlobInfo = BlobInfo.newBuilder(BlobId.of(BUCKET_NAME, thumbFileName)).build();
      // 上传缩略图到存储桶
      Files.copy(Paths.get("/tmp", blob.getName()), Paths.get("/tmp", thumbFileName));
      storage.create(thumbBlobInfo, Paths.get("/tmp", thumbFileName).toFile());
    }
  }
}