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+---
+title: 'Borg ansible role (continued)'
+description: 'The ansible role I rewrote to manage my borg backups'
+date: '2024-10-07'
+tags:
+- ansible
+- backups
+- borg
+---
+
+## Introduction
+
+I initially wrote about my borg ansible role in [a blog article three and a half years ago]({{< ref "borg-ansible-role.md" >}}). I released a second version two years ago (time flies!) and it still works well, but I am no longer using it.
+
+I put down ansible when I got infatuated with nixos a little more than a year ago. As I am dialing it back on nixos, I am reviewing and changing some of my design choices.
+
+## Borg repositories changes
+
+One of the main breaking change is that I no longer want to use one borg repository per host as my old role managed: I want one per job/application so that backups are agnostic from the hosts they are running on.
+
+The main advantages are:
+- one private ssh key per job
+- no more data expiration when a job stops running on a job for a time
+- easier monitoring of job run: now checking if a repository has new data is enough, before I had to check the number of jobs that wrote to it in a specific time frame.
+
+The main drawback is that I lose the ability to automatically clean a borg server's `authorized_keys` file when I completely stop using an application or service. Migrating from host to host is properly handled, but complete removal will be manual. I tolerate this because now each job has its own private ssh key, generated on the fly when the job is deployed to a host.
+
+## The new role
+
+### Tasks
+
+The main.yaml contains:
+
+``` yaml
+---
+- name: 'Install borg'
+ package:
+ name:
+ - 'borgbackup'
+ # This use attribute is a work around for https://github.com/ansible/ansible/issues/82598
+ # Invoking the package module without this fails in a delegate_to context
+ use: '{{ ansible_facts["pkg_mgr"] }}'
+```
+
+It will be included in a `delete_to` context when a client configures its server. For the client itself, this tasks file will run normally and be invoked from a `meta` dependency.
+
+The meat of the role is in the client.yaml:
+
+``` yaml
+---
+# Inputs:
+# client:
+# name: string
+# jobs: list(job)
+# server: string
+# With:
+# job:
+# command_to_pipe: optional(string)
+# exclude: optional(list(string))
+# name: string
+# paths: optional(list(string))
+# post_command: optional(string)
+# pre_command: optional(string)
+
+- name: 'Ensure borg directories exists on server'
+ file:
+ state: 'directory'
+ path: '{{ item }}'
+ owner: 'root'
+ mode: '0700'
+ loop:
+ - '/etc/borg'
+ - '/root/.cache/borg'
+ - '/root/.config/borg'
+
+- name: 'Generate openssh key pair'
+ openssh_keypair:
+ path: '/etc/borg/{{ client.name }}.key'
+ type: 'ed25519'
+ owner: 'root'
+ mode: '0400'
+
+- name: 'Read the public key'
+ ansible.builtin.slurp:
+ src: '/etc/borg/{{ client.name }}.key.pub'
+ register: 'borg_public_key'
+
+- include_role:
+ name: 'borg'
+ tasks_from: 'server'
+ args:
+ apply:
+ delegate_to: '{{ client.server }}'
+ vars:
+ server:
+ name: '{{ client.name }}'
+ pubkey: '{{ borg_public_key.content | b64decode | trim }}'
+
+- name: 'Deploy the jobs script'
+ template:
+ src: 'jobs.sh'
+ dest: '/etc/borg/{{ client.name }}.sh'
+ owner: 'root'
+ mode: '0500'
+
+- name: 'Deploy the systemd service and timer'
+ template:
+ src: '{{ item.src }}'
+ dest: '{{ item.dest }}'
+ owner: 'root'
+ mode: '0444'
+ notify: 'systemctl daemon-reload'
+ loop:
+ - { src: 'jobs.service', dest: '/etc/systemd/system/borg-job-{{ client.name }}.service' }
+ - { src: 'jobs.timer', dest: '/etc/systemd/system/borg-job-{{ client.name }}.timer' }
+
+- name: 'Activate job'
+ service:
+ name: 'borg-job-{{ client.name }}.timer'
+ enabled: true
+ state: 'started'
+
+```
+
+The server.yaml contains:
+
+``` yaml
+---
+# Inputs:
+# server:
+# name: string
+# pubkey: string
+
+- name: 'Run common tasks'
+ include_tasks: 'main.yaml'
+
+- name: 'Create borg group on server'
+ group:
+ name: 'borg'
+ system: 'yes'
+
+- name: 'Create borg user on server'
+ user:
+ name: 'borg'
+ group: 'borg'
+ shell: '/bin/sh'
+ home: '/srv/borg'
+ createhome: 'yes'
+ system: 'yes'
+ password: '*'
+
+- name: 'Ensure borg directories exist on server'
+ file:
+ state: 'directory'
+ path: '{{ item }}'
+ owner: 'borg'
+ mode: '0700'
+ loop:
+ - '/srv/borg/.ssh'
+ - '/srv/borg/{{ server.name }}'
+
+- name: 'Authorize client public key'
+ lineinfile:
+ path: '/srv/borg/.ssh/authorized_keys'
+ line: '{{ line }}{{ server.pubkey }}'
+ search_string: '{{ line }}'
+ create: true
+ owner: 'borg'
+ group: 'borg'
+ mode: '0400'
+ vars:
+ line: 'command="borg serve --restrict-to-path /srv/borg/{{ server.name }}",restrict '
+```
+
+### Handlers
+
+I have a single handler:
+
+``` yaml
+---
+- name: 'systemctl daemon-reload'
+ shell:
+ cmd: 'systemctl daemon-reload'
+```
+
+### Templates
+
+The `jobs.sh` script contains:
+
+``` shell
+#!/usr/bin/env bash
+###############################################################################
+# \_o< WARNING : This file is being managed by ansible! >o_/ #
+# ~~~~ ~~~~ #
+###############################################################################
+set -euo pipefail
+
+archiveSuffix=".failed"
+
+# Run borg init if the repo doesn't exist yet
+if ! borg list > /dev/null; then
+ borg init --encryption none
+fi
+
+{% for job in client.jobs %}
+archiveName="{{ ansible_fqdn }}-{{ client.name }}-{{ job.name }}-$(date +%Y-%m-%dT%H:%M:%S)"
+{% if job.pre_command is defined %}
+{{ job.pre_command }}
+{% endif %}
+{% if job.command_to_pipe is defined %}
+{{ job.command_to_pipe }} \
+ | borg create \
+ --compression auto,zstd \
+ "::${archiveName}${archiveSuffix}" \
+ -
+{% else %}
+borg create \
+ {% for exclude in job.exclude|default([]) %} --exclude {{ exclude }}{% endfor %} \
+ --compression auto,zstd \
+ "::${archiveName}${archiveSuffix}" \
+ {{ job.paths | join(" ") }}
+{% endif %}
+{% if job.post_command is defined %}
+{{ job.post_command }}
+{% endif %}
+borg rename "::${archiveName}${archiveSuffix}" "${archiveName}"
+borg prune \
+ --keep-daily=14 --keep-monthly=3 --keep-weekly=4 \
+ --glob-archives '*-{{ client.name }}-{{ job.name }}-*'
+{% endfor %}
+
+borg compact
+```
+
+The `jobs.service` systemd unit file contains:
+
+``` ini
+###############################################################################
+# \_o< WARNING : This file is being managed by ansible! >o_/ #
+# ~~~~ ~~~~ #
+###############################################################################
+
+[Unit]
+Description=BorgBackup job {{ client.name }}
+
+[Service]
+Environment="BORG_REPO=ssh://borg@{{ client.server }}/srv/borg/{{ client.name }}"
+Environment="BORG_RSH=ssh -i /etc/borg/{{ client.name }}.key -o StrictHostKeyChecking=accept-new"
+CPUSchedulingPolicy=idle
+ExecStart=/etc/borg/{{ client.name }}.sh
+Group=root
+IOSchedulingClass=idle
+PrivateTmp=true
+ProtectSystem=strict
+ReadWritePaths=/root/.cache/borg
+ReadWritePaths=/root/.config/borg
+User=root
+```
+
+Finally the `jobs.timer` systemd timer file contains:
+
+``` ini
+###############################################################################
+# \_o< WARNING : This file is being managed by ansible! >o_/ #
+# ~~~~ ~~~~ #
+###############################################################################
+
+[Unit]
+Description=BorgBackup job {{ client.name }} timer
+
+[Timer]
+OnCalendar=daily
+Persistent=false
+
+[Install]
+WantedBy=timers.target
+```
+
+## Invoking the role
+
+The role can be invoked by:
+
+``` yaml
+- include_role:
+ name: 'borg'
+ tasks_from: 'client'
+ vars:
+ client:
+ jobs:
+ - name: 'data'
+ paths:
+ - '/srv/vaultwarden'
+ - name: 'postgres'
+ command_to_pipe: "su - postgres -c '/usr/bin/pg_dump -b -c -C -d vaultwarden'"
+ name: 'vaultwarden'
+ server: '{{ vaultwarden.borg }}'
+```
+
+## Conclusion
+
+I am happy with this new design! The immediate consequence is that I am archiving my old role since I do not intend to maintain it anymore.