Add verified Prometheus backup pull to Atlas

ansible/roles/profile_server/tasks/backup_export_identity.yml

@@ -0,0 +1,103 @@
+---
+- name: Validate Prometheus backup export identity inputs
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.assert:
+    that:
+      - inventory_hostname == 'prometheus'
+      - server_backup_username is match('^[a-z_][a-z0-9_-]*$')
+      - server_backup_username not in ['root', server_username]
+      - server_backup_export_root.startswith('/var/lib/')
+      - server_backup_public_key_name is match('^[a-z0-9_-]+$')
+      - hostvars['atlas'].atlas_manage_prometheus_backup_pull | default(false) | bool
+    fail_msg: Enable Atlas and Prometheus backup roles together with dedicated identity settings.
+  when: server_backup_export_enabled | bool
+
+- name: Create dedicated Prometheus backup export group
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.group:
+    name: "{{ server_backup_username }}"
+    system: true
+    state: present
+  when: server_backup_export_enabled | bool
+
+- name: Create locked Prometheus backup export account
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.user:
+    name: "{{ server_backup_username }}"
+    group: "{{ server_backup_username }}"
+    groups: []
+    append: false
+    comment: Read-only prepared backup export for Atlas
+    home: "{{ server_backup_export_root }}"
+    create_home: false
+    shell: /bin/bash
+    password_lock: true
+    system: true
+    state: present
+  when: server_backup_export_enabled | bool
+
+- name: Require restricted rrsync helper on Prometheus
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.stat:
+    path: "{{ server_backup_rrsync_path }}"
+  register: server_backup_rrsync_file
+  when: server_backup_export_enabled | bool
+
+- name: Validate restricted rrsync helper
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.assert:
+    that:
+      - server_backup_rrsync_file.stat.exists
+      - server_backup_rrsync_file.stat.isreg
+      - server_backup_rrsync_file.stat.pw_name == 'root'
+    fail_msg: Rocky rsync must provide the root-owned rrsync support script.
+  when: server_backup_export_enabled | bool
+
+- name: Create prepared backup export root
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.file:
+    path: "{{ server_backup_export_root }}"
+    state: directory
+    owner: root
+    group: "{{ server_backup_username }}"
+    mode: "0750"
+  when: server_backup_export_enabled | bool
+
+- name: Create restricted Prometheus backup SSH directories
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.file:
+    path: "{{ item }}"
+    state: directory
+    owner: root
+    group: "{{ server_backup_username }}"
+    mode: "0750"
+  loop:
+    - "{{ server_backup_export_root }}/.ssh"
+    - "{{ server_backup_export_root }}/.ssh/authorized_keys.d"
+  when: server_backup_export_enabled | bool
+
+- name: Read Atlas public key for Prometheus backup pull
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.slurp:
+    src: "{{ hostvars['atlas'].atlas_prometheus_pull_private_key_path | default('/etc/atlas-prometheus-pull/id_ed25519') }}.pub"
+  delegate_to: atlas
+  become: true
+  register: server_backup_atlas_public_key
+  when:
+    - server_backup_export_enabled | bool
+    - not ansible_check_mode
+
+- name: Authorize only restricted read-only backup access from Atlas
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.copy:
+    content: >-
+      {{ 'command="/usr/bin/python3 ' ~ server_backup_rrsync_path ~ ' -ro '
+         ~ server_backup_export_root ~ '/versions",restrict '
+         ~ (server_backup_atlas_public_key.content | b64decode | trim) ~ '\n' }}
+    dest: "{{ server_backup_export_root }}/.ssh/authorized_keys.d/{{ server_backup_public_key_name }}"
+    owner: root
+    group: "{{ server_backup_username }}"
+    mode: "0640"
+  when:
+    - server_backup_export_enabled | bool
+    - not ansible_check_mode

ansible/roles/profile_server/tasks/backup_export_job.yml

@@ -0,0 +1,90 @@
+---
+- name: Validate Prometheus backup export job inputs
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.assert:
+    that:
+      - server_backup_export_source_keep | int >= 2
+      - server_backup_export_paths | length > 0
+      - server_backup_export_paths | unique | length == server_backup_export_paths | length
+      - >-
+        server_backup_export_paths
+        | select('match', '^[a-zA-Z0-9][a-zA-Z0-9._/-]*$') | list | length
+        == server_backup_export_paths | length
+      - >-
+        server_backup_export_paths
+        | reject('search', '(^|/)\.\.(/|$)') | list | length
+        == server_backup_export_paths | length
+      - >-
+        server_backup_export_excludes
+        | select('match', '^[a-zA-Z0-9][a-zA-Z0-9._/-]*$') | list | length
+        == server_backup_export_excludes | length
+      - >-
+        server_backup_export_excludes
+        | reject('search', '(^|/)\.\.(/|$)') | list | length
+        == server_backup_export_excludes | length
+    fail_msg: Define safe relative paths and at least two prepared export versions.
+  when: server_backup_export_enabled | bool
+
+- name: Validate Prometheus backup export calendar
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.command:
+    argv: [systemd-analyze, calendar, "{{ server_backup_export_calendar }}"]
+  changed_when: false
+  check_mode: false
+  when: server_backup_export_enabled | bool
+
+- name: Ensure prepared Prometheus backup versions directory exists
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.file:
+    path: "{{ server_backup_export_root }}/versions"
+    state: directory
+    owner: root
+    group: "{{ server_backup_username }}"
+    mode: "0750"
+  when: server_backup_export_enabled | bool
+
+- name: Install Prometheus backup export helper
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.template:
+    src: prometheus-backup-export.sh.j2
+    dest: /usr/local/sbin/prometheus-backup-export
+    owner: root
+    group: root
+    mode: "0750"
+  when: server_backup_export_enabled | bool
+
+- name: Install Prometheus backup export systemd units
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.template:
+    src: "{{ item }}.j2"
+    dest: "/etc/systemd/system/{{ item }}"
+    owner: root
+    group: root
+    mode: "0644"
+  loop:
+    - prometheus-backup-export.service
+    - prometheus-backup-export.timer
+  loop_control:
+    label: "{{ item }}"
+  register: server_backup_export_units
+  when: server_backup_export_enabled | bool
+
+- name: Reload systemd after Prometheus backup export unit changes
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.systemd:
+    daemon_reload: true
+  when:
+    - server_backup_export_enabled | bool
+    - server_backup_export_units is changed
+    - not ansible_check_mode
+
+- name: Enable Prometheus backup export timer only after explicit activation
+  tags: [services, backup, prometheus_backup]
+  ansible.builtin.systemd:
+    name: prometheus-backup-export.timer
+    enabled: true
+    state: started
+  when:
+    - server_backup_export_enabled | bool
+    - server_backup_export_start_timer | bool
+    - not ansible_check_mode

ansible/roles/profile_server/tasks/main.yml

@@ -53,6 +53,12 @@
   tags: [services, podman]
   ansible.builtin.include_tasks: podman-compose.yml
 
+- name: Import Prometheus backup export identity tasks
+  ansible.builtin.import_tasks: backup_export_identity.yml
+
+- name: Import Prometheus backup export job tasks
+  ansible.builtin.import_tasks: backup_export_job.yml
+
 - name: Ensure server SSH authorized key fragments directory exists
   tags: [services, ssh]
   ansible.builtin.file:
@@ -77,13 +83,17 @@
   when: server_ssh_authorized_keys | length > 0
 
 - name: Configure server SSH authorized key fragments
-  tags: [services, ssh]
+  tags: [services, ssh, prometheus_backup]
   ansible.builtin.lineinfile:
     path: /etc/ssh/sshd_config
     regexp: '^\s*AuthorizedKeysFile\s+'
     line: >-
-      AuthorizedKeysFile {{ server_ssh_authorized_keys | map(attribute='name')
-      | map('regex_replace', '^', '%h/.ssh/authorized_keys.d/') | join(' ') }}
+      AuthorizedKeysFile {{
+        ((server_ssh_authorized_keys | map(attribute='name')
+          | map('regex_replace', '^', '%h/.ssh/authorized_keys.d/') | list)
+        + (['%h/.ssh/authorized_keys.d/' ~ server_backup_public_key_name]
+           if server_backup_export_enabled | bool else [])) | join(' ')
+      }}
     state: present
     validate: "sshd -t -f %s"
   notify: Reload SSH service
@@ -100,11 +110,13 @@
   notify: Reload SSH service
 
 - name: Restrict SSH login to allowed users on server
-  tags: [services]
+  tags: [services, prometheus_backup]
   ansible.builtin.lineinfile:
     path: /etc/ssh/sshd_config
     regexp: '^\s*AllowUsers\s+'
-    line: "AllowUsers {{ server_sshd_allow_users | join(' ') }}"
+    line: >-
+      AllowUsers {{ (server_sshd_allow_users
+      + ([server_backup_username] if server_backup_export_enabled | bool else [])) | join(' ') }}
     state: present
     validate: "sshd -t -f %s"
   notify: Reload SSH service

ansible/roles/profile_server/templates/prometheus-backup-export.service.j2

@@ -0,0 +1,15 @@
+[Unit]
+Description=Prepare a read-only Prometheus application backup for Atlas
+RequiresMountsFor=/opt/npm /opt/gitea {{ server_backup_export_root }}
+ConditionFileIsExecutable=/usr/local/sbin/prometheus-backup-export
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/sbin/prometheus-backup-export
+User=root
+Group=root
+UMask=0077
+TimeoutStartSec=infinity
+Nice=10
+IOSchedulingClass=best-effort
+IOSchedulingPriority=7

ansible/roles/profile_server/templates/prometheus-backup-export.sh.j2

@@ -0,0 +1,92 @@
+#!/usr/bin/env bash
+set -Eeuo pipefail
+umask 077
+
+export_root={{ server_backup_export_root | quote }}
+versions="$export_root/versions"
+stack_unit=podman-compose-server.service
+stamp=$(date -u +%Y%m%dT%H%M%SZ)
+stage=''
+stack_stopped=false
+
+exec 9>/run/lock/prometheus-backup-export.lock
+flock -n 9 || { echo 'A backup export is already running' >&2; exit 1; }
+
+cleanup() {
+  local rc=$?
+  trap - EXIT
+  if "$stack_stopped"; then
+    if systemctl is-active --quiet "$stack_unit"; then
+      systemctl restart "$stack_unit" || rc=1
+    else
+      systemctl start "$stack_unit" || rc=1
+    fi
+  fi
+  if (( rc != 0 )) && [[ -n "$stage" && -d "$stage" ]]; then
+    rm -rf -- "$stage"
+  fi
+  exit "$rc"
+}
+trap cleanup EXIT
+trap 'exit 129' HUP
+trap 'exit 130' INT
+trap 'exit 143' TERM
+
+systemctl is-active --quiet "$stack_unit" || {
+  echo 'The managed Compose stack must be active before preparing a backup' >&2
+  exit 1
+}
+
+paths=(
+{% for path in server_backup_export_paths %}
+  {{ path | quote }}
+{% endfor %}
+)
+excludes=(
+{% for path in server_backup_export_excludes %}
+  --exclude={{ path | quote }}
+{% endfor %}
+)
+for path in "${paths[@]}"; do
+  [[ -e "/$path" ]] || { echo "Required backup path missing: /$path" >&2; exit 1; }
+done
+[[ ! -e "$versions/$stamp" ]] || { echo "Export version already exists: $stamp" >&2; exit 1; }
+stage=$(mktemp -d "$export_root/.staging.XXXXXXXX")
+
+# SQLite databases and their accompanying files are copied while both
+# managed containers are stopped. The EXIT trap restarts the stack on error.
+stack_stopped=true
+systemctl stop "$stack_unit"
+tar --acls --xattrs --selinux "${excludes[@]}" -C / -cf "$stage/payload.tar" "${paths[@]}"
+systemctl start "$stack_unit"
+for container in nginx-proxy-manager gitea; do
+  running=false
+  for _ in {1..30}; do
+    if [[ $(podman inspect --format '{{ '{{.State.Running}}' }}' "$container" 2>/dev/null) == true ]]; then
+      running=true
+      break
+    fi
+    sleep 2
+  done
+  "$running" || { echo "Container did not restart: $container" >&2; exit 1; }
+done
+stack_stopped=false
+
+tar -tf "$stage/payload.tar" >/dev/null
+(cd "$stage" && sha256sum payload.tar >payload.sha256)
+printf '{"schema":1,"host":"prometheus","created_utc":"%s"}\n' "$stamp" >"$stage/metadata.json"
+chown root:{{ server_backup_username }} "$stage" "$stage/payload.tar" "$stage/payload.sha256" "$stage/metadata.json"
+chmod 0750 "$stage"
+chmod 0640 "$stage/payload.tar" "$stage/payload.sha256" "$stage/metadata.json"
+mv -- "$stage" "$versions/$stamp"
+stage=''
+ln -s "$stamp" "$versions/.current.new"
+mv -Tf -- "$versions/.current.new" "$versions/current"
+
+# Keep a small source-side safety window; Atlas owns long-term retention.
+mapfile -t old_versions < <(find "$versions" -mindepth 1 -maxdepth 1 -type d \
+  -printf '%f\n' | grep -E '^[0-9]{8}T[0-9]{6}Z$' | sort -r | tail -n +{{ server_backup_export_source_keep + 1 }})
+for old in "${old_versions[@]}"; do
+  rm -rf -- "${versions:?}/$old"
+done
+echo "Prepared Prometheus backup export $stamp"

ansible/roles/profile_server/templates/prometheus-backup-export.timer.j2

@@ -0,0 +1,10 @@
+[Unit]
+Description=Prepare daily Prometheus application backup for Atlas
+
+[Timer]
+OnCalendar={{ server_backup_export_calendar }}
+Persistent=false
+Unit=prometheus-backup-export.service
+
+[Install]
+WantedBy=timers.target