#!/bin/sh
# Nightly database backup, run by the `backup` service in docker-compose.yml.
# Writes politrack-YYYY-MM-DD.dump (pg_dump custom format) to /backups at 02:30 UTC, deletes dumps older than
# $BACKUP_KEEP_DAYS days, and records each attempt as a run of "backup", so /api/v1/status/sources alerts
# when backups stop. Restore: pg_restore -h <host> -U politrack -d politrack --clean <file>
set -u
KEEP="${BACKUP_KEEP_DAYS:-14}"
export PGHOST=db PGUSER=politrack PGDATABASE=politrack

record() {  # record <status> <json stats>
  psql -q -c "INSERT INTO run (adapter, mode, status, finished_at, stats) VALUES ('backup', 'backup', '$1', now(), '$2'::jsonb)" \
    || echo "could not record the backup run"
}

while true; do
  now=$(date -u +%s)
  next=$(date -u -d "today 02:30" +%s)
  [ "$next" -le "$now" ] && next=$(date -u -d "tomorrow 02:30" +%s)
  echo "next backup at $(date -u -d "@$next")"
  sleep $((next - now))

  file="/backups/politrack-$(date -u +%F).dump"
  if pg_dump -Fc -f "$file.tmp" && mv "$file.tmp" "$file"; then
    size=$(stat -c %s "$file")
    echo "backup ok: $file ($size bytes)"
    record ok "{\"file\": \"$(basename "$file")\", \"bytes\": $size}"
  else
    rm -f "$file.tmp"
    echo "backup FAILED"
    record error '{}'
  fi
  find /backups -name 'politrack-*.dump' -mtime "+$KEEP" -delete
done