init-slave.sh

#!/bin/bash
# TODO: cover slave side selection for replication entities:
# * replicate-do-db=db_name only if we want to store and replicate certain DBs
# * replicate-ignore-db=db_name used when we don't want to replicate certain DBs
# * replicate_wild_do_table used to replicate tables based on wildcard patterns
# * replicate_wild_ignore_table used to ignore tables in replication based on wildcard patterns

REPLICATION_HEALTH_GRACE_PERIOD=${REPLICATION_HEALTH_GRACE_PERIOD:-3}
REPLICATION_HEALTH_TIMEOUT=${REPLICATION_HEALTH_TIMEOUT:-10}

echo "Waiting for MySQL Master"
until mysql -h"$MYSQL_MASTER_HOST" -P"$MYSQL_MASTER_PORT" -u"$MYSQL_REPLICATION_USER" -p"$MYSQL_REPLICATION_PASSWORD" &> /dev/null
do
  printf "."
  sleep 1
done
echo " done"

check_slave_health () {
  echo Checking replication health:
  status=$(mysql -u root -p$MYSQL_ROOT_PASSWORD -e "SHOW SLAVE STATUS\G")
  echo "$status" | egrep 'Slave_(IO|SQL)_Running:|Seconds_Behind_Master:|Last_.*_Error:' | grep -v "Error: $"
  if ! echo "$status" | grep -qs "Slave_IO_Running: Yes"    ||
     ! echo "$status" | grep -qs "Slave_SQL_Running: Yes"   ||
     ! echo "$status" | grep -qs "Seconds_Behind_Master: 0" ; then
	echo WARNING: Replication is not healthy.
    return 1
  fi
  return 0
}


echo Updating master connetion info in slave.

mysql -u root -p$MYSQL_ROOT_PASSWORD -e "RESET MASTER; \
  CHANGE MASTER TO \
  MASTER_HOST='$MYSQL_MASTER_HOST', \
  MASTER_PORT=$MYSQL_MASTER_PORT, \
  MASTER_USER='$MYSQL_REPLICATION_USER', \
  MASTER_PASSWORD='$MYSQL_REPLICATION_PASSWORD';"

mysqldump \
  --protocol=tcp \
  --user=$MYSQL_REPLICATION_USER \
  --password=$MYSQL_REPLICATION_PASSWORD \
  --host=$MYSQL_MASTER_HOST \
  --port=$MYSQL_MASTER_PORT \
  --hex-blob \
  --all-databases \
  --add-drop-database \
  --master-data \
  --flush-logs \
  --flush-privileges \
  | mysql -u root -p$MYSQL_ROOT_PASSWORD

echo mysqldump completed.

echo Starting slave ...
mysql -u root -p$MYSQL_ROOT_PASSWORD -e "START SLAVE;"

echo Initial health check:
check_slave_health

echo Waiting for health grace period and slave to be still healthy:
sleep $REPLICATION_HEALTH_GRACE_PERIOD

counter=0
while ! check_slave_health; do
  if (( counter >= $REPLICATION_HEALTH_TIMEOUT )); then
    echo ERROR: Replication not healthy, health timeout reached, failing.
	break
    exit 1
  fi
  let counter=counter+1
  sleep 1
done