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| Deletions are marked like this. | Additions are marked like this. |
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| DISCLAIMER THIS ONLY WORKS IN BUSTER |
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| * 192.168.1.58 redis01 * 192.168.1.59 redis02 * 192.168.1.60 redis03 |
* 192.168.1.59 redis01 * 192.168.1.60 redis02 * 192.168.1.61 redis03 |
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| apt-get install redis-server redis-sentinel | apt-get install redis-server |
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| Make sure the apache servers can reach redis. Change `bind 127.0.0.1` in `/etc/redis/redis.conf`. Each of the redis servers needs to listen on its own IP-address. | Change the contents of the redis configuration file in `/etc/redis/redis.conf`. |
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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. | |
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| Stop the redis server on all hosts. | Enable redis to listen on the network, instead of only listening on the loopback device. |
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| service redis-server stop | protected-mode no |
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| To enable replication we need to consider one of the redis servers the master. Here it will be redis01. On the two other hosts add the following to `/etc/redis/redis.conf`. | 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. |
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| slaveof 192.168.1.58 6379 | appendonly yes |
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| Start the redis servers again, but start it on redis01 first. | Activate redis cluster features |
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| service redis-server start | cluster-enabled yes cluster-config-file nodes-6379.conf cluster-node-timeout 15000 |
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| redis01 should now be the master. | |
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| === Redis Sentinel === The same goes for `/etc/redis/sentinel.conf` |
Restart the redis server on all hosts. |
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| bind 127.0.0.1 192.168.1.58 | service redis-server restart |
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| * https://www.tecmint.com/setup-redis-replication-in-centos-8/ * https://www.tecmint.com/setup-redis-high-availability-with-sentinel-in-centos-8/ |
DISCLAIMER THIS ONLY WORKS IN BUSTER INCOMPLETE DO NOT USE
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
- 192.168.1.60 redis02
- 192.168.1.61 redis03
Software
apt-get install redis-server
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 127.0.0.1 192.168.1.58
Enable redis to listen on the network, instead of only listening on the loopback device.
protected-mode no
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 the redis server on all hosts.
service redis-server restart
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/