Export Backup Manager archives via SFTP

Backup Manager store its backups archives on the local disk. To prevent data loss in case of hardware failure, it is recommended to create a backup copy of the archives on a remote host. This post describe how to setup Backup Manager to copy its archives to a remote host with scp.

This howto is tested on:

• Debian 10.0 Buster

Requirements

This howto requires:

• Backup Manager, as described by Install Backup Manager on Debian.
• A remote SFTP server, as described by Setup a SFTP server on Debian.

Settings

Initialize the settings associative array:

declare -A bmSettings

Set the remote user account:

bmSettings['BM_UPLOAD_SSH_USER']='bmngr'

Set the remote host addresses:

bmSettings['BM_UPLOAD_SSH_HOSTS']='server.domain.com'

Set the remote host SSH port (22 by default):

bmSettings['BM_UPLOAD_SSH_PORT']='22'

Set the remote host path where the backup will be stored:

bmSettings['BM_UPLOAD_SSH_DESTINATION']='/var/archives'

Enable the purge of old backup data:

bmSettings['BM_UPLOAD_SSH_PURGE']='true'

Set the TTL (time to live) of the backup data on the remote server (in days):

bmSettings['BM_UPLOAD_SSH_TTL']='30'

Configuration

Detect if sudo is available (“command” is used if not):

cmdProxy='command'
command type -f 'sudo' &>'/dev/null' && cmdProxy='sudo'

Set the SSH key to be used to log-in on the remote host:

bmSettings['BM_UPLOAD_SSH_KEY']='/etc/backup-manager/id_rsa'

Create the folder containing Backup Manager SSH key pair:

${cmdProxy} mkdir --parent "$(command dirname "${bmSettings['BM_UPLOAD_SSH_KEY']}")"

Create a SSH key pair with a blank password for Backup Manager:

if [ ! -e "${bmSettings['BM_UPLOAD_SSH_KEY']}" ]; then
  ${cmdProxy} ssh-keygen -t rsa -N '' -f "${bmSettings['BM_UPLOAD_SSH_KEY']}"
fi

Register the public key on the remote SSH server account:

${cmdProxy} ssh-copy-id -i "${bmSettings['BM_UPLOAD_SSH_KEY']}.pub" -p "${bmSettings['BM_UPLOAD_SSH_PORT']}" \
    "${bmSettings['BM_UPLOAD_SSH_USER']}@${bmSettings['BM_UPLOAD_SSH_HOSTS']}"

Fetch current backup upload methods:

IFS=' ' read -r -a 'backupUploadMethods' \
  <<< "$(${cmdProxy} grep '^export BM_UPLOAD_METHOD=' '/etc/backup-manager.conf' \
    | command sed -e 's/^[^=]*="\(.*\)".*$/\1/')"

Remove “none” and “scp” from existing backup upload methods:

declare -a removedMethods
removedMethods=( 'none' 'scp' )
for removedMethod in "${removedMethods[@]}"; do
  for index in "${!backupUploadMethods[@]}"; do
    [[ "${backupUploadMethods[index]}" = "${removedMethod}" ]] && unset 'backupUploadMethods[index]'
  done
done

Add “scp” to backup upload methods:

backupUploadMethods+=( 'scp' )

Update backup upload method setting:

IFS=' ' bmSettings['BM_UPLOAD_METHOD']="${backupUploadMethods[*]}"

Apply the settings:

declare -a sedOptions
sedOptions=()
for settingName in ${!bmSettings[@]}; do
  sedOptions+=( '-e' "s|[#]*\(.*${settingName}=\).*$|\1\"${bmSettings["${settingName}"]}\"|" )
done
${cmdProxy} sed -i "${sedOptions[@]}" '/etc/backup-manager.conf'