repl_delay.sh

#!/bin/bash
# Estimate time to slave replication recovery using an accumulated average

time_interval=60

samples=0
delay_moving_average=0
delay="$(mysql -e 'SHOW SLAVE STATUS\G' | awk '/Seconds_Behind_Master:/ {print $2}')"

echo "Initial replication delay: ${delay} seconds. Polling recovery rate every ${time_interval} seconds."

while [[ ${delay} > 0 ]]; do
    sleep ${time_interval}
    let "samples++"
    delay_old="${delay}"
    delay="$(mysql -e 'SHOW SLAVE STATUS\G' | awk '/Seconds_Behind_Master:/ {print $2}')"
    delay_moving_average=$(awk "BEGIN {print (${delay_old} - ${delay}) * 1/${samples} + ${delay_moving_average} * (${samples} - 1)/${samples}}")
    delay_rate=$(awk "BEGIN {printf ${delay_moving_average} / ${time_interval}}")
    echo "Replication delayed by ${delay} seconds. Recovering at a rate of ${delay_rate} seconds per second. ETA: $(awk "BEGIN {print ${delay} / ${delay_rate}}") seconds."
done