Clustered Redis in multiple AZs in a VPC with replication

gistfile1.py

def create_redis_cluster(region, infrastructure_name, security_groups, subnet_ids, availability_zones,
                         cache_node_type):

    cluster_name = "{0}-cache-cluster".format(infrastructure_name)
    replication_group = "{0}-rg".format(infrastructure_name)
    cluster_subnet = "{0}-cluster-subnet".format(infrastructure_name)

    print "Creating Redis cluster {0} using security groups {1} and subnet {2} in AZs {3} with cache node type {4}"\
        .format(cluster_name, security_groups, subnet_ids, availability_zones, cache_node_type)

    conn = boto.elasticache.connect_to_region(region)

    cache_subnet_group_name = "{0}-cache-sgn".format(infrastructure_name)
    conn.create_cache_subnet_group(
        cache_subnet_group_name=cache_subnet_group_name,
        cache_subnet_group_description=cluster_subnet,
        subnet_ids=subnet_ids
    )

    cnt = 1
    for az in availability_zones:
        print "Create cluster node in AZ {0}".format(az)
        cluster_id = "{0}00{1}".format(infrastructure_name, cnt)
        if cnt == 1:
            # Creating Redis master
            conn.create_cache_cluster(cache_cluster_id=cluster_id, num_cache_nodes=1, cache_node_type=cache_node_type,
                                      engine="redis", cache_subnet_group_name=cache_subnet_group_name,
                                      security_group_ids=security_groups, auto_minor_version_upgrade=True,
                                      preferred_availability_zone=az)
        else:
            conn.create_cache_cluster(cache_cluster_id=cluster_id,
                                      replication_group_id=replication_group)

        counter = 0
        while counter < 35:
            counter += 1
            cluster_desc = conn.describe_cache_clusters(cache_cluster_id=cluster_id)
            cluster_status = cluster_desc["DescribeCacheClustersResponse"]["DescribeCacheClustersResult"]["CacheClusters"][0]["CacheClusterStatus"]

            if "available" not in cluster_status:
                time.sleep(10)

            elif "available" in cluster_status:
                break

        if cnt == 1:
            conn.create_replication_group(replication_group_id=replication_group, primary_cluster_id=cluster_id,
                                          replication_group_description="Redis-Replication-Group")
            time.sleep(20)

        cnt += 1