Support for Docker Swarm

[vitor-luquini]

Hi, please add support for creating a docker swarm service, because when machine go offline, it is started again, I tried the following approach:

docker service create --name postgres_backup postgres-backup-s3-backup:latest --env S3_BUCKET="secret" \ --env S3_SECRET_ACCESS_KEY="secret" \ --env S3_ACCESS_KEY_ID="secret" \ --env S3_REGION="secret"

But it always struggle with 0 instances and the sh script exits with no response,

Thanks alot