Using Exoscale Compute as a Dedicated Backup Server

This guide configures an Exoscale Compute instance to automatically back up your servers to Exoscale Object Storage (SOS). The setup uses Plakar to create encrypted, deduplicated snapshots on a scheduled interval with web UI monitoring.

• Backup Compute: Runs Plakar and schedules backups
• Source servers: Exoscale servers to back up
• Exoscale Object Storage (SOS): Stores encrypted backups

flowchart TB
subgraph Sources["Source Servers"]
  Server1["Web Server 1"]
  Server2["Web Server 2"]
  ServerN["Server N"]
end

BackupCompute["Backup Compute
Plakar + Scheduler"]

subgraph Storage["Exoscale Object Storage"]
  Kloset["Kloset Store
Encrypted & Deduplicated
Backup"]
end

Server1 -->|SSH/SFTP| BackupCompute
Server2 -->|SSH/SFTP| BackupCompute
ServerN -->|SSH/SFTP| BackupCompute
BackupCompute -->|Store Snapshots| Kloset

• Exoscale account with billing configured
• SSH keypair for instance access
• SSH access to source servers
• Basic familiarity with Plakar commands

1. In the Exoscale portal, navigate to Storage
2. Click Add to create a new bucket
3. Configure:
   • Zone: Select region (note the name, it’ll be used to connect to the container e.g ch-dk-2)
   • Name: plakar-backups (must be globally unique)
4. Click Add

1. In the Exoscale portal, navigate to IAM → Keys
2. Click on Add to create new API keys, then provide a name and role, then click Create.
3. Copy the key and secret to a secure environment (you cannot see the secret once you leave the page)

1. Generate SSH key locally and copy the public key:

$ ssh-keygen -t ed25519 -f ~/.ssh/id_exoscale -C "exoscale-backup"
$ cat ~/.ssh/id_exoscale.pub

2. In the Exoscale portal, navigate to Compute → SSH Keys
3. Click on Add then enter a name for the SSH Key and paste in the public key then click Import.

1. In the Exoscale Portal, navigate to Compute → Instances
2. Click Add
3. Configure:
   • Name: plakar-backup
   • Template: Ubuntu 24.04 LTS
   • Zone: Same as Object Storage bucket (recommended for better performance)
   • Instance Type: Small (2 vCPUs, 2 GB RAM) or any other you prefer
   • SSH Key: Select the SSH key we created before from the dropdown
4. Click Add to provision your compute

1. Once the compute is provisioned, navigate to Compute → Security Groups
2. By default the compute will be assigned the default security group, click on the actions on default then click on Details
3. On the next page click on Add Rule
4. Configure:
   • Flow direction: Ingress
   • Protocol: TCP
   • Source Type: CIDR
   • Sources: 0.0.0.0/0 allows SSH from anywhere (for better security use your IP Address here)
   • Start & End port: 22
   • A description for the rule e.g. SSH Access
5. Click on Create

Once instance is running, note the public IP and connect:

$ ssh ubuntu@<instance-ip>

Install Plakar on the instance using the Plakar Installation Guide

$ plakar login -email you@example.com
$ plakar pkg add s3

$ plakar store add exoscale-sos-backups \
  location=s3://<SOS_ENDPOINT>/<BUCKET_NAME> \
  access_key=<YOUR_ACCESS_KEY> \
  secret_access_key=<YOUR_SECRET_KEY> \
  use_tls=true \
  passphrase='<YOUR_SECURE_PASSPHRASE>'

Replace:

• <SOS_ENDPOINT>: using the format sos-{zone}.exo.io where zone is one we selected for the bucket e.g sos-ch-dk-2.exo.io
• <BUCKET_NAME>: e.g., plakar-backups
• <YOUR_ACCESS_KEY> and <YOUR_SECRET_KEY>: From bucket API credentials
• <YOUR_SECURE_PASSPHRASE>: Strong passphrase for encryption

$ plakar at "@exoscale-sos-backups" create

$ plakar pkg add sftp

$ ssh-keygen -t ed25519 -f ~/.ssh/id_ed25519_plakar -C "plakar@backup"

Press Enter for no passphrase.

$ ssh-copy-id -i ~/.ssh/id_ed25519_plakar.pub user@source-server-1
$ ssh-copy-id -i ~/.ssh/id_ed25519_plakar.pub user@source-server-2

Test access:

$ ssh -i ~/.ssh/id_ed25519_plakar user@source-server-1 'echo "Success"'

$ cat >> ~/.ssh/config << 'EOF'
Host source-1
  HostName source-server-1.example.com
  User backupuser
  Port 22
  IdentityFile ~/.ssh/id_ed25519_plakar

Host source-2
  HostName source-server-2.example.com
  User backupuser
  Port 22
  IdentityFile ~/.ssh/id_ed25519_plakar
EOF

Test:

$ ssh source-1 'echo "Alias works"'

Add source connectors for each server:

$ plakar source add web-server-1 sftp://source-1:/var/www
$ plakar source add web-server-2 sftp://source-2:/var/www

Verify:

$ plakar source show

Run a manual backup to verify configuration:

# Single source
$ plakar at "@exoscale-sos-backups" backup "@web-server-1"

# Multiple sources
$ plakar at "@exoscale-sos-backups" backup "@web-server-1" "@web-server-2"

List snapshots:

$ plakar at "@exoscale-sos-backups" ls

For scheduler configuration and systemd service setup, follow the same steps as the OVHcloud backup server guide, replacing:

• @ovhcloud-s3-backups with @exoscale-sos-backups
• ubuntu with your actual username if different

The scheduler configuration, systemd services, and web UI setup are identical on any Linux machine.

Authentication errors

• Verify SSH keys and user permissions on source servers

Can’t connect to Object Storage

• Check S3 credentials and endpoint URL
• Verify passphrase: plakar store show exoscale-sos-backups
• Confirm bucket name and zone endpoint match

Permission denied

• Ensure SSH user has read access to backup directories

Services won’t start

• Check status: systemctl status plakar-scheduler
• View logs: journalctl -u plakar-scheduler or journalctl -u plakar-ui

Alternative UI access

• Install Plakar locally and configure the same store with Exoscale SOS credentials to access backups without compute instance connection