Why should a redis cluster use a reverse proxy? Just read this one

author ： Can't wait for Harmonica
link ：www.cnblogs.com/Courage129/p/14351545.html

If there is no reverse proxy , a Redis You may need to connect to many clients :

Looking at whether it's very flustered ? Look, it doesn't matter , The main reason is that the connection consumes thread resources , Without an agent ,Redis A large part of resources should be used to establish a connection with the client ,redis It's highly available and scalable, whether it's built-in Redis Sentinel still Redis Cluster Both require additional support from the client , At present, there is basically no suitable client that can do these things , It's not appropriate for clients to do these things , It makes maintenance particularly difficult .

So in the client and redis An ideal solution is to add a layer of proxy between servers , Proxy shield back end Redis The implementation details are provided to the client redis service , It's a perfect solution Redis High availability and scalability issues of , At the same time, the introduction of agent also makes Redis Maintenance becomes easier .

So , With an agent :

How to use a proxy ?

It's simple , Connect the request to the scheduling agent , from Proxy Responsible for forwarding requests to the following Redis Service instance , Icon :

There's a new problem ,Proxy Hang up, but how to fix it ?

therefore Proxy And we need to do clustering , You can even add a layer of load balancing in front of it , Load balancing , Single machine also has single point of failure and other problems , One Director Definitely not , Maybe I hung up again , So the whole host and backup , The standby plane passes through KeepAlived To detect the main LVS health , If something goes wrong, go to the top .

Redis Proxy plug-in

Redis There are many proxy plug-ins , Here are a few

predixy	High performance, all features redis agent , Support Redis Sentinel and Redis Cluster
twemproxy	Fast 、 Lightweight memcached and redis agent
codis	redis Cluster agent solution
redis-cerberus	Redis Cluster agent

Agent detailed function comparison

characteristic	predixy	twemproxy	codis	redis-cerberus
High availability	Redis Sentinel or Redis Cluster	Consistent Hashing	Redis Sentinel	Redis Cluster
Scalable	Key Hash distribution or Redis Cluster	Key Hash distribution	Key Hash distribution	Redis Cluster
development language	C++	C	GO	C++
Multithreading	yes	no	yes	yes
Business	Redis Sentinel Model sheet Redis Group support	I won't support it	I won't support it	I won't support it
BLPOP/BRPOP/BLPOPRPUSH	Support	I won't support it	I won't support it	Support
Pub/Sub	Support	I won't support it	I won't support it	Support
Script	Support load	I won't support it	I won't support it	I won't support it
Scan	Support	I won't support it	I won't support it	I won't support it
Select DB	Support	I won't support it	Support	Redis Cluster only one DB
Auth	Support to define multiple passwords , Give different read-write and management rights and Key Access space	I won't support it	Same as redis	I won't support it
Read from node	Support , Rich rules can be defined to read the specified slave node	I won't support it	Support , Simple rules	Support , Simple rules
Multi room support	Support , Rich rules can be defined to schedule traffic	I won't support it	Limited support	Limited support
Statistics	Enrich	Enrich	Enrich	Simple

Simply speaking ,predixy Support both Redis Sentinel Also support Redis Cluster

• The back end is Redis Sentinel A group of monitors Redis, The function is completely equivalent to the original Redis
• The back end is Redis Sentinel Monitoring multiple groups Redis, Some functions are limited
• The back end is Redis Cluster, The function is totally equivalent to Redis Cluster

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