file.conf

input {
  file {
    path => "/var/log/tomcat7/access.log"
    type => "apache-access"
  }
}

filter {
  grok {
    type => "apache-access"
    pattern => "%{COMBINEDAPACHELOG}"
  }
}

output {
  redis { host => "redis-host" port => "6379" data_type => "list" key => "logstash" }
}

indexer.conf

input {
  redis {
    host => "127.0.0.1"
    port => "6379"

    # these settings should match the output of the agent
    data_type => "list"
    key => "logstash"

    # We use the 'json' codec here because we expect to read
    # json events from redis.
    codec => json
  }
}

output {
  elasticsearch {
    host => "127.0.0.1"
  }
}