Skip to content

Redis High-Availability with Sentinel

Overview

High availability with Redis needs several Redis nodes and several Sentinel nodes. A typical production setup has 3 Redis instances and 3 Redis Sentinel processes on separate servers. A quorum after a failure needs three nodes.

For more information about high availability with Redis and Sentinel, read the official Redis Sentinel Documentation.

Configure Redis Sentinel cluster with LibreNMS

The LibreNMS web interface and the poller can both use a Redis Sentinel cluster as their backend.

Web UI Configuration

For a Redis Sentinel cluster in the web interface, add these parameters to your .env file:

# Configure these values according to your environment
REDIS_SENTINEL_HOSTS=redis://192.168.1.10:26379,redis://192.168.1.11:26379,redis://192.168.1.12:26379
REDIS_SENTINEL_SERVICE=mymaster
# optionally set password if your redis-backend has it enabled, this is not for sentinel.
REDIS_PASSWORD=your_redis_password

# These values tell the web app to use Sentinel as the Redis backend - do not change
REDIS_BROADCAST_CONNECTION=sentinel_cache
REDIS_CACHE_CONNECTION=sentinel_cache
REDIS_LOCK_CACHE_CONNECTION=sentinel_cache
SESSION_DRIVER=redis
SESSION_CONNECTION=sentinel_session

Redis Sentinel Authentication

If your Redis Sentinel cluster has a password, add password=your_redis_password to the end of each Redis Sentinel URL in the REDIS_SENTINEL_HOSTS variable. With ACLs, also add username=your_redis_username to the URL.

For example:

REDIS_SENTINEL_HOSTS=redis://192.168.1.10:26379?password=your_redis_password,redis://192.168.1.11:26379?password=your_redis_password,redis://192.168.1.12:26379?password=your_redis_password

Poller Configuration

For a Redis Sentinel cluster in the poller, add these lines to your .env file:

# Configure these values according to your environment
REDIS_SENTINEL=redis-001.example.org:26379,redis-002.example.org:26379,redis-003.example.org:26379
REDIS_SENTINEL_SERVICE=mymaster

# If requirepass is set in sentinel (recommended)
REDIS_SENTINEL_PASSWORD=SentinelPasswordGoesHere

# If ACLs are in use (highly recommended)
REDIS_SENTINEL_USERNAME=SentinelUsernameGoesHere
REDIS_PASSWORD=your_redis_password

For more information about the distributed polling configuration, read Distributed-Poller.md.

Testing Your Configuration

To test your Redis Sentinel setup with LibreNMS, connect to the Redis Sentinel cluster with redis-cli. Then run the MONITOR command. This command shows the commands of the Redis cluster.