Differences between revisions 13 and 37 (spanning 24 versions)

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 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

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.

service redis-server restart

Next we will need to configure the servers to run as a cluster

redis-cli --cluster create 192.168.1.59:6379 192.168.1.60:6379 192.168.1.61:6379

You should get output similar to this

>>> Performing hash slots allocation on 3 nodes...
Master[0] -> Slots 0 - 5460
Master[1] -> Slots 5461 - 10922
Master[2] -> Slots 10923 - 16383
M: 78252519c58c5e7651554b3c82ba5800e4c11c41 192.168.1.59:6379
   slots:[0-5460] (5461 slots) master
M: b26d5a1ebe4891c68acf1d6b7cea5cc19057849f 192.168.1.60:6379
   slots:[5461-10922] (5462 slots) master
M: 0db96b401cca249b61660ed4d2945d658dcdc6e1 192.168.1.61:6379
   slots:[10923-16383] (5461 slots) master
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join

>>> Performing Cluster Check (using node 192.168.1.59:6379)
M: 78252519c58c5e7651554b3c82ba5800e4c11c41 192.168.1.59:6379
   slots:[0-5460] (5461 slots) master
M: 0db96b401cca249b61660ed4d2945d658dcdc6e1 192.168.1.61:6379
   slots:[10923-16383] (5461 slots) master
M: b26d5a1ebe4891c68acf1d6b7cea5cc19057849f 192.168.1.60:6379
   slots:[5461-10922] (5462 slots) master
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.

-  ⇤ ← Revision 13 as of 2020-02-13 20:03:47 → 
  Size: 1408
  Editor: Kristian Kallenberg
  Comment:
+   ← Revision 37 as of 2021-01-04 21:46:12 → ⇥
  Size: 3538
  Editor: Kristian Kallenberg
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-INCOMPLETE DO NOT USE
-Line 7:
+Line 5:
- * 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
-Line 21:
+Line 19:
-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`.
-Line 23:
+Line 21:
+Add the IP-address for each of the servers. Each of the redis servers needs to listen on its own IP-address.
-Line 24:
+Line 23:
-bind 127.0.0.1 192.168.1.58
+bind 192.168.1.59 127.0.0.1 ::1
-Line 27:
+Line 26:
-Stop the redis server on all hosts.
+Enable redis to listen on the network, instead of only listening on the loopback device.
-Line 29:
+Line 28:
-service redis-server stop
+protected-mode no
-Line 32:
+Line 31:
-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.
-Line 34:
+Line 33:
-slaveof 192.168.1.58 6379
+appendonly yes
-Line 37:
+Line 36:
-Start the redis servers again, but start it on redis01 first.
+Activate redis cluster features
-Line 39:
+Line 38:
-service redis-server start
+cluster-enabled yes
cluster-config-file nodes-6379.conf
cluster-node-timeout 15000
-Line 41:
+Line 42:
-redis01 should now be the master.
 Line 43:
-=== Redis Sentinel ===
+Restart redis on all hosts.
{{{
service redis-server restart
}}}
-Line 45:
+Line 48:
-The same goes for `/etc/redis/sentinel.conf`
+Next we will need to configure the servers to run as a cluster
-Line 47:
+Line 50:
-bind 127.0.0.1 192.168.1.58
+redis-cli --cluster create 192.168.1.59:6379 192.168.1.60:6379 192.168.1.61:6379
-Line 49:
+Line 52:
+You should get output similar to this
{{{
>>> Performing hash slots allocation on 3 nodes...
Master[0] -> Slots 0 - 5460
Master[1] -> Slots 5461 - 10922
Master[2] -> Slots 10923 - 16383
M: 78252519c58c5e7651554b3c82ba5800e4c11c41 192.168.1.59:6379
   slots:[0-5460] (5461 slots) master
M: b26d5a1ebe4891c68acf1d6b7cea5cc19057849f 192.168.1.60:6379
   slots:[5461-10922] (5462 slots) master
M: 0db96b401cca249b61660ed4d2945d658dcdc6e1 192.168.1.61:6379
   slots:[10923-16383] (5461 slots) master
Can I set the above configuration? (type 'yes' to accept): yes
>>> Nodes configuration updated
>>> Assign a different config epoch to each node
>>> Sending CLUSTER MEET messages to join the cluster
Waiting for the cluster to join

>>> Performing Cluster Check (using node 192.168.1.59:6379)
M: 78252519c58c5e7651554b3c82ba5800e4c11c41 192.168.1.59:6379
   slots:[0-5460] (5461 slots) master
M: 0db96b401cca249b61660ed4d2945d658dcdc6e1 192.168.1.61:6379
   slots:[10923-16383] (5461 slots) master
M: b26d5a1ebe4891c68acf1d6b7cea5cc19057849f 192.168.1.60:6379
   slots:[5461-10922] (5462 slots) master
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[OK] All 16384 slots covered.
}}}
-Line 54:
+Line 89:
+ * https://www.haproxy.com/blog/haproxy-advanced-redis-health-check/
-Line 55:
+Line 91:
+ * https://blog.usejournal.com/first-step-to-redis-cluster-7712e1c31847
 * https://www.linode.com/docs/applications/big-data/how-to-install-and-configure-a-redis-cluster-on-ubuntu-1604/
 * 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/
 * https://www.tecmint.com/setup-redis-cluster-in-centos-8/
 * https://stackoverflow.com/questions/39568561/how-to-solve-redis-cluster-waiting-for-the-cluster-to-join-issue

Redis

Software

Configuration

Redis Server

References