Description

This role configures automated backups for remote backup clients which cannot reach the backup server directly, e.g. due to firewalls, NAT, etc. The backup server must be able to reach the remote client via SSH.

This role configures both restic remote clients (machines that need files backed up) and the restic REST server (which hosts the restic repositories). Once this role is deployed, the backup server starts a systemd service restic-remote-backup@<remote-client>.service, which initiates an SSH connection, forwarding the backup server's port to the remote restic client via SSH and then invoking the restic-backup.service there.

Flowchart

sequenceDiagram
    Backup Server->>+Backup Server: systemctl start [email protected]
    Backup Server->>+Remote Client: Open SSH tunnel, forward REST server port 3000,<br>execute sudo systemctl start restic-backup.service

    Remote Client->>+restic-backup.service: Starting restic-backup.service - Restic backup...
    restic-backup.service->>restic-backup.service: restic init ...<br>restic backup ...
    restic-backup.service->>Remote Client: restic: open repository at rest:http(s)://user:pass@Server:3000/Client
    Remote Client->>Remote Client: "Server" always resolves to IP 127.0.0.1
    restic-backup.service->>Backup Server: using parent snapshot d289ee09<br>...<br>snapshot fa15be6f saved
    restic-backup.service->>-Remote Client: restic-backup.service: Deactivated successfully.
    Remote Client->>-Backup Server: Finished restic-backup.service - Restic backup.
    Backup Server->>-Backup Server: [email protected]: Succeeded.

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You can regard this role as kind of an extension to the fifty2technology.restic_client role, as they are both integrated into each other, but it once made more sense to unload the restic_client role and separate the "remote client" functionality from it. It is also coupled with the fifty2technology.restic_server role, since the backup server needs to be configured to connect to remote clients - this means it can only work with clients with a restic REST server account configured as a repository.

Once a week (on saturday night) the backup server also connects to each remote client and runs the restic-prune.service.

For monitoring purposes and if configured, the backup server connects to each remote machine once every day via [email protected] to gather metrics about the latest backup snapshot. This cannot be done by the client itself since it requires access to the restic repository on the server.

Requirements

• The variable restic_client_is_remote must be set to true to enable remote backups. It must also be set during restic_client role deployment so it configures and activates systemd services correctly.
• backup_server must be set to the inventory_hostname of the backup server, e.g. backupserver.example.com.
• backup_server_password must contain the login credentials for the backup server if SSH password-authentication is used. With key-based authentication, this can be left undefined (will default to empty string).
• backup_server_become_password must contain the privilege escalation password for the unprivileged user on the backup server. The same as above applies here in case of key-based authentication.

The backup_server_*password variables are necessary for password-only authentication, so that delegate_to tasks to the backup server are run correctly. It is not necessary if you use SSH login with keys and/or as privileged user.

Role Variables

All variables which can be overridden are stored in defaults/main.yml file as well as in table below.

Name	Default value	Description
restic_remote_server_user	"{{ restic_server_user | default('rest-server') }}"	Username to use for initiating SSH connections as from server to client
restic_remote_server_group	"{{ restic_server_group | default('rest-server') }}"	Groupname used to assert that a SSH private/public keypair exists with correct ownership on the server. The keypair should exist already (created in restic_server role).
restic_remote_client_port	"{{ restic_server_listen_port | default('3000') }}"	Port to use on client side to terminate SSH tunnel coming from the backup server. Set to a port not used by something else on the client. Defaults to the same port the restic_server role uses to let the REST server listen on.
restic_remote_client_user	"{{ restic_client_user | default('restic') }}"	Username used by the server to connect to the client via SSH. The server then starts the restic-backup.service as this user via sudo systemctl start restic-backup.service.
restic_remote_ssh_port	22	SSH port of the client, which will be used by the backup server to connect. This role does not configure 'Port' in SSHD config!
restic_remote_client_group	"{{ restic_client_group | default('restic') }}"	Groupname getting granted sudo privileges on client to start systemd services restic-backup.service and restic-prune.service. The client's user must be in this group.
restic_remote_client_is_remote	"{{ restic_client_is_remote | default(false) }}"	Repeat from restic_client role to check whether client should be configured to be backed up remotely by the backup server.
restic_remote_no_log	true	Do not show sensible content when printed by ansible-playbook runs. Set to false for debugging e.g. repository file templating.

Dependencies

The restic_client role must be run on targets beforehand, and the restic_server role for the restic rest-server must be deployed already.

Example Playbook

- hosts: all
  gather_facts: false
  become: true

  vars:
    restic_client_is_remote: true
    backup_server: backupserver.example.com

  roles:
    - role: restic_client
    - role: restic_remote

Testing with Molecule

Example how to fully test the whole restic_remote role from deploy to a remote backup trigger:

1. Run molecule converge
2. Run molecule login -h backupserver to login to the backupserver container.
   1. Run systemctl start restic-remote-backup@restic_remote_debian12.service to test if the backup is working.
   2. Run journalctl -fe to check for possible errors.
3. Run molecule login -h restic_remote_debian12
   1. Run journalctl -ft restic to check for possible errors.

Dependig on the container environment, molecule containers might not be able to resolve each others hostnames, breaking the SSH connection attempts in the restic-remote-backup@<remote-client>.service. In this case, add the restic_remote_debian12 hostname to /etc/hosts manually on the backupserver. In a productive setup, hostnames must be resolvable via DNS.