#!/bin/sh
# usr - uptime server reloader, v0.4
# Checks a health URL. After USR_FAILS failed checks in a row it runs USR_CMD.
# Meant to be started once a minute by a systemd timer or cron.
set -eu
URL="${USR_URL:-http://127.0.0.1:8080/health}"
CMD="${USR_CMD:-systemctl reload myapp}"
FAILS="${USR_FAILS:-3}"
TIMEOUT="${USR_TIMEOUT:-5}"
STATE="${USR_STATE:-/run/usr.count}"

count=$(cat "$STATE" 2>/dev/null || echo 0)
if curl -fsS -m "$TIMEOUT" -o /dev/null "$URL"; then
    [ "$count" -gt 0 ] && logger -t usr "recovered after $count failed check(s)"
    echo 0 > "$STATE"
    exit 0
fi
count=$((count + 1))
echo "$count" > "$STATE"
logger -t usr "check $count/$FAILS failed for $URL"
if [ "$count" -ge "$FAILS" ]; then
    logger -t usr "running: $CMD"
    sh -c "$CMD" && echo 0 > "$STATE"
fi