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| DISCLAIMER THIS ONLY WORKS IN BUSTER INCOMPLETE DO NOT USE |
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| * 192.168.1.59 redis01 * 192.168.1.60 redis02 * 192.168.1.61 redis03 |
* 192.168.1.59 redis01 (master) * 192.168.1.60 redis02 (replica) * 192.168.1.61 redis03 (replica) |
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| apt-get install redis-server | apt-get install redis-server redis-sentinel |
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| Add the IP-address for each of the servers. Each of the redis servers needs to listen on its own IP-address. Due to a bug in redis, the added IP-address will have to be in the beginning of the line, right next to `bind`. If the IP-address is added in the end of the line, then the cluster will not initialize itself, and `Waiting for the cluster to join` message wil continuously write dots. | Add the IP-address for each of the servers. Each of the redis servers needs to listen on its own IP-address. |
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| bind 192.168.1.58 127.0.0.1 ::1 | bind 192.168.1.59 127.0.0.1 ::1 |
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| Redis stores its data in memory only, hence its speed. To make sure redis does not loose its state, in case of a hardware failure, this will enable it to store the state as it changes in a file on disk. {{{ appendonly yes }}} Activate redis cluster features {{{ cluster-enabled yes cluster-config-file nodes-6379.conf cluster-node-timeout 15000 }}} Restart redis on all hosts. |
Now restart the redis master |
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| Next we will need to configure the servers to run as a cluster | And stop the replicas |
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| redis-cli --cluster create 192.168.1.59:6379 192.168.1.60:6379 192.168.1.61:6379 | service redis-server stop |
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On each of the replicas, set them up af a replica of the master {{{ replicaof 192.168.1.59 }}} Start the replicas again {{{ services redis-server start }}} |
Redis
Redis is an in memory data structure storage. It will be used to share PHP-sessions between the apache servers. To guarantee a robust deployment three redis servers will be configured.
- 192.168.1.59 redis01 (master)
- 192.168.1.60 redis02 (replica)
- 192.168.1.61 redis03 (replica)
Software
apt-get install redis-server redis-sentinel
Configuration
Redis Server
Change the contents of the redis configuration file in /etc/redis/redis.conf.
Add the IP-address for each of the servers. Each of the redis servers needs to listen on its own IP-address.
bind 192.168.1.59 127.0.0.1 ::1
Enable redis to listen on the network, instead of only listening on the loopback device.
protected-mode no
Now restart the redis master
service redis-server restart
And stop the replicas
service redis-server stop
On each of the replicas, set them up af a replica of the master
replicaof 192.168.1.59
Start the replicas again
services redis-server start
References
https://www.haproxy.com/blog/haproxy-advanced-redis-health-check/
https://blog.usejournal.com/first-step-to-redis-cluster-7712e1c31847
https://www.willandskill.se/en/setup-a-highly-available-redis-cluster-with-sentinel-and-haproxy/
https://www.tecmint.com/setup-redis-replication-in-centos-8/
https://www.tecmint.com/setup-redis-high-availability-with-sentinel-in-centos-8/