maintenance-elasticache.sh

#!/bin/sh

#
# CACHE CLUSTER ID
#
PRI_CACHE_CLUSTER_ID=ec-test-pri
REP_CACHE_CLUSTER_ID=ec-test-rep

#
# REPLICATION GROUP ID
#
REP_GROUP_ID=ec-test-rg

#
# make read replica
#
aws elasticache create-cache-cluster --cache-cluster-id ${REP_CACHE_CLUSTER_ID} --replication-group-id ${REP_GROUP_ID}

# wait 15 minutes for creating read replica
sleep 900

#
# get endpoint of read replica
#
REP_ENDPOINT=`aws elasticache describe-replication-groups --replication-group-id ${REP_GROUP_ID} | grep Address | grep ${REP_CACHE_CLUSTER_ID} | cut -d ':' -f 2 | sed 's/[^"]*"\([^"]*\)"[^"]*/\1/g'`

#
# check status of replication
#
while true
do
    REP_STATUS=`redis-cli -h ${REP_ENDPOINT} info | grep master_sync_in_progress | cut -d ':' -f 2 | tr -d '\r'`
#
# promote from read replica to primary
#

    if [ "${REP_STATUS}" = "0" ];
    then
        aws elasticache modify-replication-group --replication-group-id ${REP_GROUP_ID} --primary-cluster-id ${REP_CACHE_CLUSTER_ID} --apply-immediately
        break
    fi

done

# wait 1 minute for changing status of cache node primary <-> read replica
sleep 60

#
# delete read replica
#
while true
do
    RG_STATUS=`aws elasticache describe-replication-groups --replication-group-id ec-test-rg | grep replica | cut -d ':' -f 2 | sed 's/[^"]*"\([^"]*\)"[^"]*/\1/g'`
    if [ "${RG_STATUS}" = "replica" ];
    then
        aws elasticache delete-cache-cluster --cache-cluster-id ${PRI_CACHE_CLUSTER_ID}
        break
    fi
done

exit 0