Launches a cluster with 3 nodes and 3 sentinel instances to demonstrate how automated redis failover and recovery behaves.

redis-sentinel-local-cluster.sh

#!/bin/bash
PASSWORD="badpassword"

create_config(){
cat <<EOF > "${1}"
port 555"${2}"
sentinel monitor mycluster 127.0.0.1 7770 2
sentinel down-after-milliseconds mycluster 5000
sentinel failover-timeout mycluster 60000
sentinel parallel-syncs mycluster 1
sentinel auth-pass mycluster "${PASSWORD}"
EOF
}

# start up three instances of both redis and sentinel using 0,1,2 for the configs and stuff
for n in {0..2}
do
  # create a directory for each server's config file
  instance_dir="${PWD}"/redis-local-"${n}"
  mkdir "${instance_dir}" 2>/dev/null

  # create a redis-conf for each instance so dumb.rdb is saved to a unique location
  echo dir "${instance_dir}" > "${instance_dir}"/redis.conf
  # each redis instance needs a unique port on localhost
  echo port 777"${n}" >> "${instance_dir}"/redis.conf
  # use append only mode
  echo appendonly yes >> "${instance_dir}"/redis.conf
  # set a password for authenticating the replicas to the primary
  echo masterauth "${PASSWORD}" >> "${instance_dir}"/redis.conf
  # set password to protect all remote operations
  echo 'user default on +@all ~* >'"${PASSWORD}" >> "${instance_dir}"/redis.conf

  if [ ! -f "${instance_dir}"/sentinel.conf ]
  then
    # when sentinel.conf doesn't exist start redis as primary or replica's connected to primary
    if [ "${n}" == "0" ]
    then
      # start primary
      redis-server "${instance_dir}"/redis.conf &>"${instance_dir}"/redis.log &
    else
      # start replica
      redis-server "${instance_dir}"/redis.conf --replicaof 127.0.0.1 7770 &>"${instance_dir}"/redis.log &
    fi

    # create a sentinel config file for each instance on first run only
    create_config "${instance_dir}"/sentinel.conf "${n}"

  # sentinel.conf exists so just start redis
  else
    redis-server "${instance_dir}"/redis.conf &>"${instance_dir}"/redis.log &
  fi

  # start sentinel
  redis-sentinel "${instance_dir}"/sentinel.conf &>"${instance_dir}"/sentinel.log &
done

wait