#!/bin/bash
# Managed by Ansible (role restic_backup).
#
#   restic-backup run                 hooks, then backup + forget to every repository
#   restic-backup init                create the repositories that do not exist yet
#   restic-backup <repo> <args...>    plain restic against one repository, e.g.
#                                     restic-backup hel1 snapshots
#                                     restic-backup fsn1 restore latest --target /tmp/r
#
# Repositories: {{ restic_repositories.keys() | join(', ') }}
set -uo pipefail

set -a; . /etc/restic/env; set +a
export RESTIC_CACHE_DIR=/var/cache/restic
STAGE={{ restic_stage_dir }}

declare -A REPOS=(
{% for name, url in restic_repositories.items() %}
  [{{ name }}]="{{ url }}"
{% endfor %}
)

log() { echo "restic-backup: $*"; }

# Last good backup per repository, for Prometheus (node_exporter textfile)
metric() {
  local f={{ monitoring_textfile_dir }}/restic_$1.prom
  printf '# HELP restic_backup_last_success_timestamp_seconds Last successful restic backup.\n# TYPE restic_backup_last_success_timestamp_seconds gauge\nrestic_backup_last_success_timestamp_seconds{repo="%s"} %s\n' "$1" "$(date +%s)" > "$f.tmp" && mv "$f.tmp" "$f"
}

case "${1:-}" in
init)
  for name in "${!REPOS[@]}"; do
    if RESTIC_REPOSITORY="${REPOS[$name]}" restic cat config >/dev/null 2>&1; then
      log "$name: exists"
    else
      RESTIC_REPOSITORY="${REPOS[$name]}" restic init || exit 1
      log "$name: created"
    fi
  done
  ;;

run)
  failed=0
  rm -rf "$STAGE"; install -d -m 700 "$STAGE"
  export STAGE
{% for hook in restic_pre_hooks %}
  log "hook {{ loop.index }}/{{ restic_pre_hooks | length }}"
  ( set -e; {{ hook }} ) || { log "hook failed"; failed=1; }
{% endfor %}

  for name in "${!REPOS[@]}"; do
    export RESTIC_REPOSITORY="${REPOS[$name]}"
    log "$name: backup"
    restic backup --host {{ inventory_hostname }} --one-file-system --exclude-caches \
{% for e in restic_excludes %}
      --exclude '{{ e }}' \
{% endfor %}
      {{ (restic_paths + [restic_stage_dir]) | join(' ') }} || { failed=1; continue; }

    prune=""
    [ "$(date +%a)" = "{{ restic_prune_weekday }}" ] && prune="--prune"
    log "$name: forget $prune"
    restic forget --host {{ inventory_hostname }} {{ restic_keep }} $prune || failed=1
    metric "$name"
  done

  rm -rf "$STAGE"
  exit $failed
  ;;

*)
  [ -n "${1:-}" ] && [ -n "${REPOS[$1]:-}" ] || { sed -n '4,10p' "$0"; exit 2; }
  export RESTIC_REPOSITORY="${REPOS[$1]}"; shift
  exec restic "$@"
  ;;
esac