I finally got S3-compatible buckets online, using a Hetzner storage box as the storage. I know they got S3 buckets as well but I am cheap and it will only be used for backups so I don’t care about speed.

For the setup I first used the Kubernetes SMB CSI driver to be able to use my storage box as regular PVC’s. On top of that I am running the Versity gateway. It is a completely stateless S3 server that can use a normal posix filesystem for the storage. It stores everything as plain files, so even without the gateway my files are still fully accessible. I could also spin up a gateway instance wherever I need one, even if my k8 cluster goes down. And I can run it in high availability on my cluster. All these things makes it perfect for backups. And it has nice web interface as a bonus. And of course it is written in Go.

apiVersion: v1
kind: PersistentVolumeClaim
metadata:
  name: versitygw-s3
  namespace: default
spec:
  accessModes:
    - ReadWriteOnce
  storageClassName: smb
  resources:
    requests:
      storage: 30Gi