REDIS

Redis operation guide. Redis is used to reduce the number of writes in cassandra and to reply last queries.

MAINTENANCE

  1. /etc/init.d/leela-redis watchdog-stop; sleep 60 # leela will no longer use this machine
  2. /etc/init.d/leela-redis stop # stops the service; now both redis are down
  3. # do your thing
  4. /etc/init.d/leela-redis start

ADDING INSTANCE

  1. make sure the file /etc/consul/conf.d/redis.service exists and is properly configured. This file should come from CFengine.
  2. /etc/init.d/leela-redis start

REMOVING INSTANCE

  1. /etc/init.d/leela-redir watchdog-stop; sleep 60

CLUSTER INFO

  • curl -s "http://webleela.service.ita.consul.locaweb.com.br/v2?q=using%20(::)%20stat;&tree=locaweb::locaweb&format=json" \ | python -m json.tool | grep redis -A1

Each of these endpoints must have two redis. The second redis must be listening at port + 1. For instance, if redis bound to 6379, the second one must be listening at 6380.

This second redis must be a slave of the first in a master-slave replication configuration. It is used to serve read queries to avoid blocking the master. As you know, redis is single threaded and we don't want the reads negatively impacting the write path.