exemplo-upload.js

//component

<Dropzone
  onDrop={async acceptedFiles => {
    if (acceptedFiles.length > 1) {
      toaster.warning("Limite 1 imagem");
      return;
    }
    const files = [];
    for (const file of acceptedFiles) {
      const fileName = await Upload("pasta-no-s3", file);
      files.push({ name: fileName });
    }

    files.forEach(item => {
      setImagem({ image: item.name });
    });

    setMainImage(files);
  }}
>
  {({ getRootProps, getInputProps }) => (
    <SectionGallery>
      <div {...getRootProps()}>
        <input {...getInputProps()} />
        {mainImage.length === 0 && (
          <p> #1 Selecione a imagem principal</p>
        )}
        {mainImage.map((item, idx) => (
          <img
            key={idx}
            src={`${process.env.REACT_APP_ASSETS_BUCKET}/pasta/${item.name}`}
            width="100px"
            height="100px"
          />
        ))}
      </div>
    </SectionGallery>
  )}
</Dropzone>

// upload
import AWS from "aws-sdk/global";
import S3 from "aws-sdk/clients/s3";

export const IMAGE_URL = `${process.env.REACT_APP_ASSETS_BUCKET}`;
export const S3_NAME = `${process.env.REACT_APP_ASSETS_BUCKET_NAME}`;

export async function Upload(folder, file) {
  const creds = {
    bucket: `${S3_NAME}/${folder}`,
    access_key: process.env.REACT_APP_ACCESS_KEY,
    secret_key: process.env.REACT_APP_SECRET_KEY
  };

  if (file === null) {
    return null;
  }

  const extension = file.type.split("/")[1];
  const name = file.name.split(".")[0];
  const fileName = `${name}-${new Date().getTime()}.${extension}`;

  AWS.config.update({
    accessKeyId: creds.access_key,
    secretAccessKey: creds.secret_key
  });
  AWS.config.region = "sa-east-1";

  const bucket = new S3({ params: { Bucket: creds.bucket, Key: fileName } });
  const params = {
    Key: fileName,
    ContentType: file.type,
    Body: file,
    ServerSideEncryption: "AES256"
  };

  await bucket.putObject(params).promise();
  return fileName;
}