Redis¶
Redis is an advanced key-value cache and store. In Spinal Stack it is used as :
- a backend for Ceilometer
- a backend for Sensu API
Configuration¶
| Configuration | Description | Default |
|---|---|---|
| redis | Enable HAProxy binding | true |
| redis_bind_ip | IP address on which Redis will be listening | Internal Network IP |
| redis_port | Port on which Redis will listening | 6379 |
| redis_bind_options | HAProxy bind options | HAProxy default bind options |
| redis_haproxy_port | Port on which HAProxy will bind to for Redis traffic | 6379 |
| sentinel_port | Port on which sentinel will listening | 26739 |
| sentinel_down_after | Time in ms an instance should not be reachable for a Sentinel starting to think it is down | 1000 |
| sentinel_failover_timeout | The time needed to restart a failover after a previous failover was already tried against the same master by a given Sentinel | 1000 |
| sentinel_notification_script | Script called for any sentinel event that is generated in the WARNING level (for instance -sdown, -odown, and so forth) | /bin/redis-notifications.sh |
| redis_master_name | Hostname of the Redis master | |
| redis_master_ip | IP address of the Redis master | redis_master_name |
| sentinel_haproxy_monitor_ip | IP address of the HAProxy Redis is ran behind | Public Virtual IP |
| sentinel_haproxy_monitor_port | Port of the HAProxy API Redis is ran behind | 10300 |
Warning
The redis_master_name parameter is mandatory. Without it the deployment of Redis in a HA setup will fail.
puppet-openstack-cloud¶
- cloud::database::nosql::redis::server
- cloud::database::nosql::redis::sentinel
Non-HA Setup¶
In a non-HA setup, only the following parameters are necessary to configure: redis, redis_bind_ip, redis_port, redis_bind_options, redis_haproxy_port.
To deploy Redis in a non-HA setup, include the ‘database::nosql::redis::server’ on the concerned node in your scenario and adjust the aforementioned parameters in the environment file.
HA Setup¶
In an HA setup, all the aforementioned parameters will have an impact on your setup.
To deploy Redis in HA setup, include both ‘database::nosql::redis::server’ and ‘database::nosql::redis::sentinel’ on the concerned nodes in your scenario.
How does it work ?¶
HA Redis architecture
Redis is deployed in an active/passive setup. Redis stream will always land on the same Redis server, the master, through HAProxy. On the node where Redis runs, there is another process called Sentinel that is also running, this process is in charge of electing a master in case the master fails. If the master fails, the sentinel will detect this change and notify HAProxy to route the Redis stream to the new elected Redis master.