Docker swarm installs redis cluster (bitnami/redis cluster:latest)

1. Preparing the cluster environment ：docker-79、docker-80、docker-81
   
2. Pull the mirror image ：

docker pull bitnami/redis-cluster:latest

3. Create a new... In any folder compose.yml Script ：redis_compose.yml

abnormal

SELECT is not allowed in cluster mode

Open the connection , Tips ：SELECT is not allowed in cluster mode

This is because redis In stand-alone mode redis.conf The default number of databases in the configuration file is 16 individual , This configuration does not work in cluster mode , Cluster clients do not support multiple databases db Of , Only one database defaults to SELECT 0;

redis The cluster version only uses db0,select The command can support select 0. Other db Will return an error .

CLUSTERDOWN Hash slot not served

Use cluster info look down redis State of the cluster ：

You can see that the cluster status is fail , And the number of slots below is 0 , This is very abnormal .

Enter the container in turn ：docker exec -it Containers ID bash

perform ：redis-cli -c -h 172.17.0.1 -p 6379

It can be connected normally redis, And then execute ：cluster meet 172.17.0.1 6379

This IP(172.17.0.1) by docker Internal default network IP：

If there is no password , Will prompt directly OK If you have a password Need to enter ： auth redis password

This meet The command is very beautiful , To make the nodes in the cluster know each other ？？？ Then continue to operate the other two servers IP, Let them know each other .

After this step , Finding out doesn't solve the problem , Try to write a value into the client , Still prompt this exception .

And then execute it in the container ：redis-cli --cluster info 192.168.104.79:6379 -a [email protected] , among [email protected] by redis Cluster password , If there is no password , You don't have to add -a password , Find out slots Slot It's empty , This is why the above problem is wrong .

root@docker-80:/# redis-cli --cluster info 192.168.104.79:6379 -a huauN@2021
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
192.168.104.79:6379 (6ce9026c...) -> 0 keys | 0 slots | 0 slaves.
[OK] 0 keys in 1 masters.
0.00 keys per slot on average.
root@docker-80:/# 

Then use redis-cli --cluster fix Perform cluster repair

root@docker-80:/# 
root@docker-80:/# redis-cli --cluster fix 192.168.104.79:6379 -a huauN@2021    
Warning: Using a password with '-a' or '-u' option on the command line interface may not be safe.
192.168.104.79:6379 (6ce9026c...) -> 0 keys | 0 slots | 0 slaves.
[OK] 0 keys in 1 masters.
0.00 keys per slot on average.
>>> Performing Cluster Check (using node 192.168.104.79:6379)
M: 6ce9026c9f438f8025323bf13787e43f08dc33bd 192.168.104.79:6379
   slots: (0 slots) master
[OK] All nodes agree about slots configuration.
>>> Check for open slots...
>>> Check slots coverage...
[ERR] Not all 16384 slots are covered by nodes.

>>> Fixing slots coverage...
The following uncovered slots have no keys across the cluster:
[0-16383]
Fix these slots by covering with a random node? (type 'yes' to accept): yes
>>> Covering slot 660 with 192.168.104.79:6379
>>> Covering slot 4315 with 192.168.104.79:6379
>>> Covering slot 13760 with 192.168.104.79:6379
>>> Covering slot 10315 with 192.168.104.79:6379

The input will then confirm whether to repair the slot ：Fix these slots by covering with a random node? (type 'yes' to accept):, Input here yes The slot will be repaired automatically , Wait for the scrolling output to end , Look at the node information , Here's the picture , Number of slots is 16384, That is, the number of normal single node slots .

Now , Directly view the slot points of the other two machines , You can see , It's all normal .

At this time , Test with client connection redis Normal use ：

This... Also exists automatically on the other two machines key：

At this time , Let's look at the cluster status , It has become ok 了 ：