Redis Streams — alert when XPENDING grows
A Redis Streams consumer lags — it reads messages but never XACKs them (the worker hangs between read and ack). XLEN does not grow, XPENDING does.
Recipe
#!/usr/bin/env bash
# /etc/cron.d/redis-streams
# */2 * * * * root /opt/redis-streams.sh
HOST=${REDIS_HOST:-127.0.0.1}
STREAM=${STREAM}
GROUP=${CONSUMER_GROUP}
THRESH=${THRESH:-100} # alert above pending count
PENDING=$(redis-cli -h "$HOST" XPENDING "$STREAM" "$GROUP" | head -1)
if [ "${PENDING:-0}" -gt "$THRESH" ]; then
curl -fsS "$HEARTBEAT_URL" --data "pending=$PENDING,stream=$STREAM,group=$GROUP"
exit 2
fi
echo "OK (pending=$PENDING)"Same thing in Enterno.io
Wire to an Enterno heartbeat — a couple of minutes without ack from the consumer is already a trend, you spot it before pipeline-wide degradation.
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