When you run one instance for 30 minutes and then terminate the instance, you're billed for one instance-hour.

export const main: any = async (event, context, callback) => {
  const fileName = event.pathParameters ? event.pathParameters.filepath : 'index.html'
  const file = await S3.get(fileName, config.S3_WEB_CLIENT_BUCKET)
  return {
    statusCode: 200,
    headers: {
      'Content-Type': 'application/octet-stream',
      'Content-Disposition': `attachment; filename=${fileName}`,
    },
    body: file.Body.toString('base64'),
  }
}