Linux Redis集群搭建与集群客户端实现

xiaoxiao2021-02-28  21

硬件环境

本文适用的硬件环境如下

Linux版本:CentOS release 6.7 (Final) Redis版本:3.2.1

Redis已经成功安装,安装路径为/home/idata/yangfan/local/redis-3.2.1。

我们要在单台机器上搭建Redis集群,方式是通过不同的TCP端口启动多个实例,然后组成集群。

 

1、启动Redis多个实例

我们在Redis安装目录下创建目录cluster,并编写7000.conf~7005.conf 6个配置文件,这6个配置文件用来启动6个实例,后面将使用这6个实例组成集群。

以7000.conf为例,配置文件需要填写如下几项。

port 7000 //端口7000,7002,7003 bind 10.93.84.53 //默认ip为127.0.0.1 需要改为其他节点机器可访问的ip 否则创建集群时无法访问对应的端口,无法创建集群 daemonize yes //redis后台运行 pidfile ./redis_7000.pid //pidfile文件对应7000,7001,7002 cluster-enabled yes //开启集群 把注释#去掉 cluster-config-file nodes_7000.conf //集群的配置 配置文件首次启动自动生成 7000,7001,7002 cluster-node-timeout 15000 //请求超时 默认15秒,可自行设置 appendonly yes //aof日志开启 有需要就开启,它会每次写操作都记录一条日志 

分别启动6个实例

./bin/redis-server cluster/conf/7000.conf ./bin/redis-server cluster/conf/7001.conf ./bin/redis-server cluster/conf/7002.conf ./bin/redis-server cluster/conf/7003.conf ./bin/redis-server cluster/conf/7004.conf ./bin/redis-server cluster/conf/7005.conf

启动成功后,看一下进程

# ps -ef | grep redis | grep cluster idata 15711 22329 0 18:40 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7000 [cluster] idata 15740 22329 0 18:40 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7001 [cluster] idata 15810 22329 0 18:40 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7002 [cluster] idata 17023 22329 0 18:42 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7003 [cluster] idata 17030 22329 0 18:42 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7004 [cluster] idata 17035 22329 0 18:42 pts/10 00:00:00 ./bin/redis-server 10.93.84.53:7005 [cluster]

至此,ip=10.93.84.53机器上创建了6个实例,端口号为port=7000~7005。

 

Redis 3.0以上的集群方式是通过Redis安装目录下的bin/redis-trib.rb脚本搭建。

这个脚本是用Ruby编写的,尝试运行,如果打印如下,你可以跳过本文的第二部分。

idata@qa-f1502-xg01.xg01:~/yangfan/local/redis-3.2.1/bin$ ruby redis-trib.rb Usage: redis-trib <command> <options> <arguments ...> create host1:port1 ... hostN:portN --replicas <arg> check host:port info host:port fix host:port --timeout <arg> reshard host:port --from <arg> --to <arg> --slots <arg> --yes --timeout <arg> --pipeline <arg> rebalance host:port --weight <arg> --auto-weights --use-empty-masters --timeout <arg> --simulate --pipeline <arg> --threshold <arg> add-node new_host:new_port existing_host:existing_port --slave --master-id <arg> del-node host:port node_id set-timeout host:port milliseconds call host:port command arg arg .. arg import host:port --from <arg> --copy --replace help (show this help) For check, fix, reshard, del-node, set-timeout you can specify the host and port of any working node in the cluster.

如果执行失败,那么不幸的是你的机器没有Ruby运行的环境,那么你需要安装Ruby。进入第二部分。

 

2、安装ruby

下面的过程都是在root权限下完成的。

1)yum安装ruby和依赖的包。

# yum -y install ruby ruby-devel rubygems rpm-build

一般来说,这一步是能正常完成的。

 

2)使用gem这个命令来安装redis接口

gem是ruby的一个工具包

# gem install redis

安装过程出错

郁闷,看样子要升级ruby版本。

 

3)升级Ruby的版本

安装rvm,我不知道这是个什么东西,但是感觉像是Ruby的一个包管理器。

# curl -L get.rvm.io | bash -s stable

WTF,又出问题了

气急败坏的照着他说的做

# gpg2 --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3 gpg: keyring `/root/.gnupg/secring.gpg' created gpg: requesting key D39DC0E3 from hkp server keys.gnupg.net gpg: /root/.gnupg/trustdb.gpg: trustdb created gpg: key D39DC0E3: public key "Michal Papis (RVM signing) <mpapis@gmail.com>" imported gpg: no ultimately trusted keys found gpg: Total number processed: 1 gpg: imported: 1 (RSA: 1)

然后重新下载rvm安装,成功了。

# curl -L get.rvm.io | bash -s stable % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 24090 100 24090 0 0 18023 0 0:00:01 0:00:01 --:--:-- 129k Downloading https://github.com/rvm/rvm/archive/1.29.3.tar.gz Downloading https://github.com/rvm/rvm/releases/download/1.29.3/1.29.3.tar.gz.asc gpg: Signature made Mon 11 Sep 2017 04:59:21 AM CST using RSA key ID BF04FF17 gpg: Good signature from "Michal Papis (RVM signing) <mpapis@gmail.com>" gpg: aka "Michal Papis <michal.papis@toptal.com>" gpg: aka "[jpeg image of size 5015]" gpg: WARNING: This key is not certified with a trusted signature! gpg: There is no indication that the signature belongs to the owner. Primary key fingerprint: 409B 6B17 96C2 7546 2A17 0311 3804 BB82 D39D C0E3 Subkey fingerprint: 62C9 E5F4 DA30 0D94 AC36 166B E206 C29F BF04 FF17 GPG verified '/usr/local/rvm/archives/rvm-1.29.3.tgz' Creating group 'rvm' Installing RVM to /usr/local/rvm/ Installation of RVM in /usr/local/rvm/ is almost complete: * First you need to add all users that will be using rvm to 'rvm' group, and logout - login again, anyone using rvm will be operating with `umask u=rwx,g=rwx,o=rx`. * To start using RVM you need to run `source /etc/profile.d/rvm.sh` in all your open shell windows, in rare cases you need to reopen all shell windows.

接着,source环境,让rvm可用。

# source /usr/local/rvm/scripts/rvm

查看Ruby可用版本

# rvm list known # MRI Rubies [ruby-]1.8.6[-p420] [ruby-]1.8.7[-head] # security released on head [ruby-]1.9.1[-p431] [ruby-]1.9.2[-p330] [ruby-]1.9.3[-p551] [ruby-]2.0.0[-p648] [ruby-]2.1[.10] [ruby-]2.2[.7] [ruby-]2.3[.4] [ruby-]2.4[.1]

可以看到最新的版本是2.4.1,那么我们装最新的吧。

# rvm install 2.4.1 Searching for binary rubies, this might take some time. No binary rubies available for: centos/6/x86_64/ruby-2.4.1. Continuing with compilation. Please read 'rvm help mount' to get more information on binary rubies. Checking requirements for centos. Installing requirements for centos. Installing required packages: libffi-devel, libyaml-devel...... Requirements installation successful. Installing Ruby from source to: /usr/local/rvm/rubies/ruby-2.4.1, this may take a while depending on your cpu(s)... ruby-2.4.1 - #downloading ruby-2.4.1, this may take a while depending on your connection... curl: (35) SSL connect error There was an error(35). Checking fallback: https://ftp.ruby-lang.org/pub/ruby/2.4/ruby-2.4.1.tar.bz2 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 11.9M 100 11.9M 0 0 1753k 0 0:00:07 0:00:07 --:--:-- 2919k ruby-2.4.1 - #extracting ruby-2.4.1 to /usr/local/rvm/src/ruby-2.4.1.... ruby-2.4.1 - #applying patch /usr/local/rvm/patches/ruby/2.4.1/random_c_using_NR_prefix.patch. ruby-2.4.1 - #configuring.................................................................. ruby-2.4.1 - #post-configuration.. ruby-2.4.1 - #compiling.............................................................................................. ruby-2.4.1 - #installing......................... ruby-2.4.1 - #making binaries executable.. ruby-2.4.1 - #downloading rubygems-2.6.14 % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 751k 100 751k 0 0 443k 0 0:00:01 0:00:01 --:--:-- 628k No checksum for downloaded archive, recording checksum in user configuration. ruby-2.4.1 - #extracting rubygems-2.6.14.... ruby-2.4.1 - #removing old rubygems......... ruby-2.4.1 - #installing rubygems-2.6.14........................... ruby-2.4.1 - #gemset created /usr/local/rvm/gems/ruby-2.4.1@global ruby-2.4.1 - #importing gemset /usr/local/rvm/gemsets/global.gems............................................... ruby-2.4.1 - #generating global wrappers........ ruby-2.4.1 - #gemset created /usr/local/rvm/gems/ruby-2.4.1 ruby-2.4.1 - #importing gemsetfile /usr/local/rvm/gemsets/default.gems evaluated to empty gem list ruby-2.4.1 - #generating default wrappers........ ruby-2.4.1 - #adjusting #shebangs for (gem irb erb ri rdoc testrb rake). Install of ruby-2.4.1 - #complete Ruby was built without documentation, to build it run: rvm docs generate-ri

至此,我们升级了Ruby的版本。

 

4)安装gem redis接口,成功!

gem install redis Fetching: redis-4.0.1.gem (100%) Successfully installed redis-4.0.1 Parsing documentation for redis-4.0.1 Installing ri documentation for redis-4.0.1 Done installing documentation for redis after 0 seconds 1 gem installed

 

5)安装rubygems,成功!

# yum install -y rubygems Loaded plugins: fastestmirror, security Setting up Install Process Loading mirror speeds from cached hostfile base | 3.7 kB 00:00 didi_jenkins_enable | 1.5 kB 00:00 didi_op_toa_enable | 1.5 kB 00:00 didi_txjenkins_enable | 1.5 kB 00:00 didi_update | 1.5 kB 00:00 epel | 4.3 kB 00:00 extras | 3.4 kB 00:00 tmprepo | 1.5 kB 00:00 updates | 3.4 kB 00:00 Package rubygems-1.3.7-5.el6.noarch already installed and latest version Nothing to do

至此,我们的Ruby和运行redis-trib.rb需要的环境安装完成了。 

 

3、Redis集群搭建

有了Ruby执行环境,可以开始将之前的6个实例组建成集群了。

命令方式:

ruby ./bin/redis-trib.rb create --replicas 1 10.93.84.53:7000 10.93.84.53:7001 10.93.84.53:7002 10.93.84.53:7003 10.93.84.53:7004 10.93.84.53:7005 --replicas 1表示为集群的master节点创建1个副本。那么6个实例里,有三个master,有三个是slave。 后面跟上6个实例就好了,形式就是ip:port

执行情况:

# ruby ./bin/redis-trib.rb create --replicas 1 10.93.84.53:7000 10.93.84.53:7001 10.93.84.53:7002 10.93.84.53:7003 10.93.84.53:7004 10.93.84.53:7005 >>> Creating cluster >>> Performing hash slots allocation on 6 nodes... Using 3 masters: 10.93.84.53:7000 10.93.84.53:7001 10.93.84.53:7002 Adding replica 10.93.84.53:7003 to 10.93.84.53:7000 Adding replica 10.93.84.53:7004 to 10.93.84.53:7001 Adding replica 10.93.84.53:7005 to 10.93.84.53:7002 M: 6346ae8c7af7949658619fcf4021cc7aca454819 10.93.84.53:7000 slots:0-5460 (5461 slots) master M: 5ac973bceab0d486c497345fe884ff54d1bb225a 10.93.84.53:7001 slots:5461-10922 (5462 slots) master M: cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 10.93.84.53:7002 slots:10923-16383 (5461 slots) master S: 92f62ec93a0550d962f81213ca7e9b3c9c996afd 10.93.84.53:7003 replicates 6346ae8c7af7949658619fcf4021cc7aca454819 S: 942c9f97dc68198c39f425d13df0d8e3c40c5a58 10.93.84.53:7004 replicates 5ac973bceab0d486c497345fe884ff54d1bb225a S: a92a81532b63652bbd862be6f19a9bd8832e5e05 10.93.84.53:7005 replicates cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 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 10.93.84.53:7000) M: 6346ae8c7af7949658619fcf4021cc7aca454819 10.93.84.53:7000 slots:0-5460 (5461 slots) master 1 additional replica(s) S: a92a81532b63652bbd862be6f19a9bd8832e5e05 10.93.84.53:7005 slots: (0 slots) slave replicates cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 M: 5ac973bceab0d486c497345fe884ff54d1bb225a 10.93.84.53:7001 slots:5461-10922 (5462 slots) master 1 additional replica(s) S: 942c9f97dc68198c39f425d13df0d8e3c40c5a58 10.93.84.53:7004 slots: (0 slots) slave replicates 5ac973bceab0d486c497345fe884ff54d1bb225a S: 92f62ec93a0550d962f81213ca7e9b3c9c996afd 10.93.84.53:7003 slots: (0 slots) slave replicates 6346ae8c7af7949658619fcf4021cc7aca454819 M: cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 10.93.84.53:7002 slots:10923-16383 (5461 slots) master 1 additional replica(s) [OK] All nodes agree about slots configuration. >>> Check for open slots... >>> Check slots coverage... [OK] All 16384 slots covered.

 可以看到16384个slot都已经创建完成,并且建立了3个master和对应的replica:

Using 3 masters: 10.93.84.53:7000 10.93.84.53:7001 10.93.84.53:7002 Adding replica 10.93.84.53:7003 to 10.93.84.53:7000 Adding replica 10.93.84.53:7004 to 10.93.84.53:7001 Adding replica 10.93.84.53:7005 to 10.93.84.53:7002 。。。 [OK] All 16384 slots covered.

 

 

4、验证集群状态

登录集群客户端,-c标识以集群方式登录

./bin/redis-cli -h 10.93.84.53 -p 7000 -c

查看集群状态

10.93.84.53:7000> cluster info cluster_state:ok cluster_slots_assigned:16384 cluster_slots_ok:16384 cluster_slots_pfail:0 cluster_slots_fail:0 cluster_known_nodes:6 cluster_size:3 cluster_current_epoch:8 cluster_my_epoch:8 cluster_stats_messages_sent:215 cluster_stats_messages_received:215 10.93.84.53:7000> cluster nodes 942c9f97dc68198c39f425d13df0d8e3c40c5a58 10.93.84.53:7004 slave 5ac973bceab0d486c497345fe884ff54d1bb225a 0 1507806791940 5 connected 5ac973bceab0d486c497345fe884ff54d1bb225a 10.93.84.53:7001 master - 0 1507806788937 2 connected 5461-10922 a92a81532b63652bbd862be6f19a9bd8832e5e05 10.93.84.53:7005 slave cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 0 1507806790939 6 connected cc46a4a1c0ec3f621b6b5405c6c10b7cffe73932 10.93.84.53:7002 master - 0 1507806789937 3 connected 10923-16383 6346ae8c7af7949658619fcf4021cc7aca454819 10.93.84.53:7000 myself,slave 92f62ec93a0550d962f81213ca7e9b3c9c996afd 0 0 1 connected 92f62ec93a0550d962f81213ca7e9b3c9c996afd 10.93.84.53:7003 master - 0 1507806792941 8 connected 0-5460

 一些原理

redis cluster在设计的时候,就考虑到了去中心化,去中间件,也就是说,集群中的每个节点都是平等的关系,都是对等的,每个节点都保存各自的数据和整个集群的状态。每个节点都和其他所有节点连接,而且这些连接保持活跃,这样就保证了我们只需要连接集群中的任意一个节点,就可以获取到其他节点的数据。

Redis集群没有并使用传统的一致性哈希来分配数据,而是采用另外一种叫做哈希槽(hash slot)的方式来分配的,一致性哈希对向集群中新增和删除实例的支持很好,但是哈希槽对向集群新增实例或者删除实例的话,需要额外的操作,需要手动的将slot重新平均的分配到新集群的实例中。

redis cluster 默认分配了 16384 个slot,当我们set一个key时,会用CRC16算法来取模得到所属的slot,然后将这个key分到哈希槽区间的节点上,具体算法就是:CRC16(key)384。

Redis 集群会把数据存在一个master节点,然后在这个master和其对应的salve之间进行数据同步。当读取数据时,也根据一致性哈希算法到对应的master节点获取数据。只有当一个master 挂掉之后,才会启动一个对应的salve节点,充当master。

需要注意的是:必须要3个或以上的主节点,否则在创建集群时会失败,并且当存活的主节点数小于总节点数的一半时,整个集群就无法提供服务了。

 

5、python集群客户端

以Python Redis Cluster集群的使用方式为例,简单说明一下如何使用,让大家更直观的了解一下Redis集群。

Redis集群方式与单机方式在python客户端实现上是有很大不同的。

包不同,单机依赖包redis-py,集群依赖包redis-py-cluster对同时操作多个keys的命令(mset, mget, sinter, ...),redis-py-cluster重写StriceRedis(单机Redis操作类)了其方法,而这些方法丧失了命令的原子性。Pipelines在集群中的表现也不同了。在单机版中,pipeline是批量batch提交redis批量执行的,但是在集群版中,是one by one提交redis执行完成直接返回,在客户端重新组合成一个列表返回。所以集群中只是看起来像是批量执行。一些命令是会Fanout(扇形)发送到集群中各个shard中执行并汇总的,如ping,keys等。一些命令是不提倡使用(blocked),如watch,unwatch等。

我只是简单翻译了官网的一些内容,相信信息大家可以参考:

http://redis-py-cluster.readthedocs.io/en/master/commands.html

http://redis-py-cluster.readthedocs.io/en/master/limitations-and-differences.html

 

1)安装redis-py-cluster 

简单的通过pip安装redis-py-cluster包。如果安装失败,可以自助下载安装。

# pip install redis-py-cluster Collecting redis-py-cluster Downloading redis_py_cluster-1.3.4-py2.py3-none-any.whl Requirement already satisfied: redis>=2.10.2 in /home/idata/pythonEnv/idataPlatEnv/lib/python2.7/site-packages/redis-2.10.5-py2.7.egg (from redis-py-cluster) Installing collected packages: redis-py-cluster Successfully installed redis-py-cluster-1.3.4

 

2)一个简单的demo

封装了RedisCluster操作类,实现了一些方法,其实就是做了一层封装。

封装的意义是:我喜欢对这些封装增加一些装饰器,控制异常和重试等逻辑。

# -*- coding:utf-8 -*- from rediscluster import StrictRedisCluster redis_nodes = [ {'host': '10.93.84.53', 'port': 7000}, {'host': '10.93.84.53', 'port': 7001}, {'host': '10.93.84.53', 'port': 7002}, {'host': '10.93.84.53', 'port': 7003}, {'host': '10.93.84.53', 'port': 7004}, {'host': '10.93.84.53', 'port': 7005}, ] class RedisCluster(object): def __init__(self, redis_nodes): self.cluster = StrictRedisCluster(startup_nodes=redis_nodes) # 无差别的方法 def set(self, name, value, ex=None, px=None, nx=False, xx=False): return self.cluster.set(name, value, ex, px, nx, xx) # 无差别的方法 def get(self, name): return self.cluster.get(name) # 扇形发送的命令 def cluster_info(self): return self.cluster.cluster_info() # 重写StrictRedis的方法 def mset(self, *args, **kwargs): return self.cluster.mset(args, kwargs) # 重写StrictRedis的方法 def mget(self, keys, *args): return self.cluster.mget(keys, args) cluster = RedisCluster(redis_nodes) cluster.cluster_info()
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