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Varaverk/Tools/arr_rescan_monitor.sh
T
Gmer4Lfe e8b114094a Bring script headers onto the template and close safeguard gaps
Headers claimed protections the code never had, and several destructive paths had no
guard against a collapsed config value.
2026-08-01 20:37:59 -04:00

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#!/bin/bash
# ==============================================================================================
# ========================= Arr Rescan Monitor ==================================================
# ==============================================================================================
#
# PURPOSE
# ─────────────────────────────────────────────────────────────────────────────
# Waits for an already-active rescan-type command (RescanFolders/RescanSeries/RescanMovie,
# DownloadedXScan, RefreshX — see ARR_RESCAN_COMMANDS in common.sh) on the given arr to finish,
# then refreshes the shared tracked-data cache (arr_cache_write) with the real post-scan
# numbers. Triggers nothing itself — for watching a rescan that was already started some
# other way (manual API call, arr's own UI, another script).
#
# Exists because arr_cache_write() now refuses to write while a rescan is active for that arr
# (2026-07-17 — a direct cache write mid-scan read as real data loss to every consumer of the
# cache, e.g. check_tracked_count_floor, instead of what it was: an in-flight scan). That
# guard protects the cache, but it also means nothing writes the real number through once the
# scan finishes unless something is watching for completion — arr_full_rescan.sh already does
# this for scans it triggers itself; this tool covers everything else.
#
# ==============================================================================================
# OPERATIONAL MODEL
# ==============================================================================================
#
# 1. Validate the arr type and resolve its URL / API key / API version
# 2. Poll /command for any active rescan-type command (ARR_RESCAN_COMMANDS)
# none active → nothing to watch, exit cleanly
# 3. Wait for it to leave the active state, bounded by the timeout argument
# (default 7200s — a full-library scan is slow by nature)
# 4. Once finished, fetch the library and arr_cache_write() the real numbers
#
# Triggers nothing. It only watches a scan someone or something else started.
#
# ==============================================================================================
# DESIGN PRINCIPLES
# ==============================================================================================
#
# Watch, Never Trigger
# This tool deliberately starts nothing. Its whole job is to be the thing that notices a
# scan finished, so a rescan begun by hand, by the arr's own UI, or by another script
# still gets its result written through to the shared cache.
#
# Complement to the Write Guard
# arr_cache_write() refuses to write while a rescan is active, because a mid-scan snapshot
# reads as real data loss to consumers like check_tracked_count_floor. That guard protects
# the cache but leaves nobody to write the true number afterwards. arr_full_rescan.sh
# covers the scans it starts itself; this covers every other origin.
#
# Bounded Wait
# The wait is capped by the timeout argument, so a scan that stalls or never reports
# completion cannot leave this running indefinitely holding its lock.
#
# ==============================================================================================
# CONFIGURATION
# ==============================================================================================
#
# host*.conf (aliased by detect_hosts())
#
# SONARR_URL / SONARR_API_KEY
# RADARR_URL / RADARR_API_KEY
# LIDARR_URL / LIDARR_API_KEY
# Connection details for whichever arr is passed as the first argument.
#
# common.sh
#
# ARR_RESCAN_COMMANDS
# Command names treated as a rescan for this purpose — shared with
# arr_cache_write()'s own active-scan guard so both agree on what counts.
#
# ARR_API_VERSION
# Per-arr API version map (v3 for Sonarr/Radarr, v1 for Lidarr).
#
# ==============================================================================================
# OPERATIONAL SAFEGUARDS
# ==============================================================================================
#
# Root required — matches convention across Arrs_Stack/Tools/, writes cache files
# Arg validation — arr_type must be lidarr/sonarr/radarr, usage error otherwise
# Timeout, never waits forever — default 2h ceiling, override via second positional arg;
# on timeout, cache is left untouched rather than acted on stale
# --status mode — read-only, shows active rescan + cache age, waits/writes nothing
# --dry-run mode — shows what would be waited on, waits/writes nothing
# Triggers nothing — never starts a rescan itself, only watches one already running;
# use arr_full_rescan.sh or the arr's own UI/API to start one
#
# ==============================================================================================
# RUNTIME MODES
# ==============================================================================================
#
# arr_rescan_monitor.sh lidarr
# Wait for lidarr's active rescan (if any) to finish, then refresh its cache.
# Exits immediately if no rescan is currently active — nothing to wait for.
#
# arr_rescan_monitor.sh lidarr 3600
# Override the default 2-hour wait ceiling (second positional arg, seconds).
#
# arr_rescan_monitor.sh lidarr --status
# Show whether a rescan is currently active and the cache's current age, no waiting.
#
# arr_rescan_monitor.sh lidarr --dry-run
# Show what would be waited on without actually waiting or writing the cache.
#
# ==============================================================================================
SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
source "$SCRIPT_DIR/../load_config.sh"
parse_args "$@"
if [[ "$EUID" -ne 0 ]]; then
error "Must be run as root"
exit 1
fi
# This writes the shared tracked-data cache on completion. Two monitors watching the same
# arr would both write it, and the loser's stale snapshot could land last.
acquire_lock
detect_hosts
ARR_TYPE="${PARSED_ARGS[0]:-}"
TIMEOUT="${PARSED_ARGS[1]:-7200}"
case "$ARR_TYPE" in
lidarr|sonarr|radarr) ;;
*) error "Usage: arr_rescan_monitor.sh lidarr|sonarr|radarr [timeout_seconds] [--status] [--dry-run]"; exit 1 ;;
esac
url_var="${ARR_TYPE^^}_URL"; key_var="${ARR_TYPE^^}_API_KEY"
URL="${!url_var:-}"; KEY="${!key_var:-}"
VER="${ARR_API_VERSION[$ARR_TYPE]}"
require_var "$url_var"
require_var "$key_var"
ACTIVE=$(arr_active_rescan_command "$ARR_TYPE" "$URL" "$KEY" "$VER")
CACHE_AGE=$(arr_cache_age_seconds "$ARR_TYPE")
if [[ "$SHOW_STATUS" == true ]]; then
info "${ARR_TYPE^} active rescan: ${ACTIVE:-none}"
info "${ARR_TYPE^} cache age: $(( CACHE_AGE / 60 )) minutes"
exit 0
fi
if [[ -z "$ACTIVE" ]]; then
info "No active rescan on ${ARR_TYPE^} — nothing to wait for."
exit 0
fi
if [[ "$DRY_RUN" == true ]]; then
warn "DRY RUN — would wait for ${ARR_TYPE^}'s active $ACTIVE (timeout ${TIMEOUT}s), then refresh its cache"
exit 0
fi
info "Waiting for ${ARR_TYPE^}'s active $ACTIVE to finish (timeout ${TIMEOUT}s)..."
if ! arr_wait_for_active_rescan "$ARR_TYPE" "$URL" "$KEY" "$VER" "$TIMEOUT"; then
error "Timed out after ${TIMEOUT}s waiting for ${ARR_TYPE^}'s rescan — cache not refreshed. Re-run once it finishes, or it'll pick up naturally next time something calls arr_get_tracked_data()."
exit 1
fi
ENDPOINT="${ARR_LIBRARY_ENDPOINT[$ARR_TYPE]}"
EXPR="${ARR_TRACKED_COUNT_EXPR[$ARR_TYPE]}"
ITEMS=$(curl -sf --max-time 60 -H "X-Api-Key: $KEY" "${URL}/api/${VER}/${ENDPOINT}" 2>/dev/null)
TOTAL=$(echo "$ITEMS" | jq "$EXPR" 2>/dev/null)
if [[ -z "$ITEMS" || -z "$TOTAL" || "$TOTAL" == "null" ]]; then
error "${ARR_TYPE^} rescan finished but couldn't fetch fresh library data — cache not refreshed"
exit 1
fi
arr_cache_write "$ARR_TYPE" "$ITEMS"
success "${ARR_TYPE^} rescan finished — cache refreshed, tracked: ${TOTAL}"
notify "${ARR_TYPE^} rescan finished on $(hostname) — cache refreshed, tracked: ${TOTAL}" "Arr Rescan Monitor" "normal"