Setup minio as backup target for Synology HyperBackup

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After some unsuccessful tests with WireGuard VPN, I’ve tried something new to provide a suitable encrypted backup target for my Synology NAS.

Minio is a block storage server which is compatible to AWS S3 API. That means I can configure a S3 compatible target in HyperBackup. Here’s now a small installation guide for a Raspberry Pi, which I’ve modified for my needs:


Download a copy of minio for arm and make it executable:

chmod +x minio
sudo mv minio /usr/local/bin/

Be aware that this download is sometimes very slow, especially from Europ. There’s an open issue but looks like the conversation is locked and no one was able to complain about it again.

We need a user for the minio process to run:

sudo groupadd --system minio
sudo useradd -s /sbin/nologin --system -g minio minio
sudo usermod -a -G minio,staff minio

We need to give ownership of the minio working directory and access to the binary, so we can update it later on:

sudo chown -R minio:minio /data/
sudo chown minio:minio /usr/local/bin/minio

Grant it additional networking permissions:

sudo setcap cap_net_bind_service=+ep /usr/local/bin/minio


Now we configure a service for starting minio using Systemd, writing the following lines into /etc/systemd/system/minio.service. Make sure to set the right working directory.



ExecStartPre=/bin/bash -c "if [ -z \"${MINIO_VOLUMES}\" ]; then echo \"Variable MINIO_VOLUMES not set in /etc/default/minio\"; exit 1; fi"

ExecStart=/usr/local/bin/minio server $MINIO_OPTS $MINIO_VOLUMES

# Let systemd restart this service always

# Specifies the maximum file descriptor number that can be opened by this process

# Disable timeout logic and wait until process is stopped


Create a minio environment file in /etc/default/minio. This setups the credentials for minio (access key and secret key), as well as the volume (same as the working directory). I’ve added a parameter for the URL under which minio will be reachable (MINIO_DOMAIN) as well as a parameter to the options on where the certificates for TLS encryption should reside (-certs-dir):

# Volume to be used for Minio server.
# Use if you want to run Minio on a custom port
MINIO_OPTS="--certs-dir /data/.minio/certs --address :443 --console-port :13380"
# Access Key of the server. Older versions used MINIO_ACCESS_KEY instead
MINIO_ROOT_USER= <someAccessKey>
# Secret key of the server. Older versions used MINIO_SECRET_KEY instead
# Server Domain, don't use a wildcard here or virtual style paths won't work!
MINIO_DOMAIN= <domain>

Reload systemd:

sudo systemctl daemon-reload

If you want to have minio starting at system startup:

sudo systemctl enable minio

TLS encryption and lets encrypt

You should enable TLS by placing a private key, a certificate and eventually a CA certificate into the path supplied by the -certs-dir parameter. In my example it would be /data/.minio/certs. You can read more about securing minio with certificates under this link.

I’ve started with the creation of a wildcard certificate created by my own trusted CA. However, you could create the same result by using Lets Encrypt. It’s important to use a wildcard certificate, as this is a requirement for using minio as backup target with Hyper Backup. We’ll run minio in virtual-host-style requests. That’s also the reason why you’ll need to define the MINIO_DOMAIN variable.

Instead of adding the bucket name to the server domain, the bucket name will be put in front of the server domain. So you’ll end up with domains like bucket. instead of /bucket. This is the reason why you’ll need a wildcard certificate for the given domain.

As I’m using all-inkl as hosting provider, I was keen to know if I could use Let’s Encrypt wildcard certificates in combination with the DDNS solution offered. However, for using Let’s encrypt certificates, you’ll need access to your domains DNS records and need to have a way to update TXT records, as the certs will automatically expire after 90 days. The general setup in combination with all-inkl is explained here.

This was also the place, where I found kasserver. kasserver provides an interface to the adminstration interface of all-inkl. It’s especially useful for setting up Let’s encrypt certs using certbot.

Install pip and venv

I had to reinstall the raspberry pi and had to do a few preparations before kasserver could be installed. The python was installed via APT, so it was managed externally. This caused some troubles for me and I had to create a dedicated environment, that is available as system-site-package:

sudo apt install python3.11-venv
python3 -m venv ~/.local --system-site-packages

The python packages that are now installed are put into the venv in ~/.local. Its bin folder is normally part of the PATH environment variable, so every command installed here will be available after you log again to a new shell.

Install kasserver

Install it with

~/.local/bin/pip install kasserver
sudo apt-get install libxslt-dev

Setup the KAS credentials in ~/.netrc

password PASSWORD

Restrict access to the file to only your user

chmod 600 ~/.netrc

Test the installation with

kasserver-dns list your.domain

Install certbot

sudo apt-get install certbot

Setup a user and folder for certbot

sudo groupadd --system letsencrypt
sudo useradd -s /sbin/nologin --system -g letsencrypt letsencrypt
sudo mkdir -p /etc/letsencrypt
sudo chown -R letsencrypt:letsencrypt /etc/letsencrypt
sudo mkdir -p /var/log/letsencrypt
sudo chown -R letsencrypt:letsencrypt /var/log/letsencrypt
sudo mkdir -p /var/lib/letsencrypt
sudo chown -R letsencrypt:letsencrypt /var/lib/letsencrypt
sudo usermod -a -G letsencrypt pi

mkdir ~/letsencrypt
mkdir ~/letsencrypt/config
mkdir ~/letsencrypt/work
mkdir ~/letsencrypt/logs

Request a certificate that is valid as wildcard cert and also for the top domain:

certbot certonly -d * --config-dir /home/pi/letsencrypt/config --work-dir /home/pi/letsencrypt/work --logs-dir /home/pi/letsencrypt/logs --preferred-challenges dns --manual --manual-auth-hook /home/pi/.local/bin/kasserver-dns-certbot --manual-cleanup-hook /home/pi/.local/bin/kasserver-dns-certbot -m your@email.domain

Setup NTFS formatted USB drive

I’ve got an NTFS formatted USB drive attached to the pi. It’s my backup storage. I’ve selected NTFS since it can be read by macOS without problems. For ext4 I’ll need to use FUSE or Paragon extFS, which I don’t want to buy.

The setup for the NTFS drive is explained in good detail here.

Make sure that you’ll add the user that mounts the NTFS drive is also part of the minio group, e.g. sudo usermod -a -G minio,staff,usergroup minio. I’ve even tried to mount the complete drive as minio:minio using this entry in /etc/fstab to avoid permissions problems:

UUID=4EE12D1B5321171F /mnt/backups ntfs-3g      auto,exec,rw,uid=995,gid=991    0       2

The ID of the minio user can be found using

id minio
uid=995(minio) gid=991(minio) Gruppen=991(minio),50(staff)

However, as we can see later on, I’ve changed this back to the ID of my raspberry pi user, e.g. pi.

Restart and testing

You can start minio using:

sudo systemctl start minio

Read the entire log:

journalctl -u minio

Once it is started, you can reach it via https://[serverip|localhost]:9000. You can login to the web interface using the two keys defined in the /etc/default/minio file.

Create a new bucket. You’ll use this bucket as your backup target in Hyper Backup.

The setup of Hyper Backup with S3 compatible providers is explained here.

Import of existing data

When you’ve already got data on your machine and want to add it to an Bucket, you’ll need to use the mc tool. First, you’ll have to setup an alias:

mc alias set destminio https://localhost minioadminuser minioadminpassword

Now you can test this locally. Since you’re connecting to localhost, you’ll have to disable the certificate check as well.

mc admin info destminio --insecure

Import the data from the local filesystem:

mc mirror /volume/old-data destminio/yourBucketName --insecure

Be aware, this is a very slow operation (around 5MB/s on a Raspberry Pi 3b).

Run as docker container

I’ve had some troubles with the setup of minio so I’ve tried to use it via docker.

Install docker

There’s a really good documentation for installing the official docker packages and not the ones provided by Rasbpian. Quite nice and worked out of the box.

Minio in docker

On my raspberry Pi 3b, I required an arvm7 compatible image. The official docker image doesn’t provide this so I’ve selected this one instead: tobi312/minio:latest

I’ve setup my docker-compose.yml like this:

version: '2'
      container_name: minio
      command: ["server", "--certs-dir", "/certs", "--address", ":443", "--console-address", ":9001", "/data"]
        - MINIO_ROOT_USER=foo
      image: tobi312/minio:latest
      user: 1000:1000
        - '443:443'
        - '9001:9001' 
        - /home/pi/letsencrytp/config/live/
        - /home/pi/letsencrytp/config/live/
        - /home/pi/letsencrytp/config/live/
        - /mnt/backups/minio:/data
        test: ["CMD", "curl", "-fail", "http://localhost:443/minio/health/live"]
        interval: 60s 
        timeout: 10s 
        retries: 3
      restart: unless-stopped

Whereby MINIO_ROOT_USER and MINIO_ROOT_PASSWORD are the same as before the Access and Secret Key. Make sure that you’ll set MINIO_DOMAIN without wildcards. The ID should be the same ID as of the user that owns the letsencrypt certificate files as well as the mounted data directory.

Start the compose file with docker compose up -d when you’re next to the docker-compose.yml file.

Reconnect S3 Hyperbackup

If you change your domain or S3 provider, you’ll have to reconnect an existing Hyperbackup key with a new S3 destination. Create a new S3 backup, select S3 as destination and choose a custom configuration. Use the credentials you’ve used before, including the new URL. Hyperbackup tries to connect automatically to the S3 server and lets you select the bucket and eventually any existing folders in that bucket. I’ve selected here the folder where I’ve imported my existing Hyperbackup.

Hyperbackup asks for a schedule and which folders to backup. I’ve selected none, but when askes for the encryption key or password of the backup, you’ll can connect an existing backup with the new location. Hyperbackup will download Meta information about the backup, which takes some time, depending on your connectivity and the connectivity of your S3 server. It then shows that it is reassociating the backup, so I assume it will show later up with all its contents and settings which were backed up. I’ll update this post accordingly, when I know more.