1, Master slave replication
Quick start practice
Based on Redis, a Master-Slave architecture is designed, including one Master and two slaves. The Master is responsible for reading and writing Redis and synchronizing data to the Slave. The Slave is only responsible for reading. The steps are as follows:
First, duplicate redis01, for example:
cp -r redis01/ redis02
cp -r redis01/ redis03
Step 2: if there are existing redis services, first stop all the original redis services (docker rm -f redis container name) and start a new redis container, for example:
docker run -p 6379:6379 --name redis6379 \ -v /usr/local/docker/redis01/data:/data \ -v /usr/local/docker/redis01/conf/redis.conf:/etc/redis/redis.conf \ -d redis redis-server /etc/redis/redis.conf \ --appendonly yes
docker run -p 6380:6379 --name redis6380 \ -v /usr/local/docker/redis02/data:/data \ -v /usr/local/docker/redis02/conf/redis.conf:/etc/redis/redis.conf \ -d redis redis-server /etc/redis/redis.conf \ --appendonly yes
docker run -p 6381:6379 --name redis6381 \ -v /usr/local/docker/redis03/data:/data \ -v /usr/local/docker/redis03/conf/redis.conf:/etc/redis/redis.conf \ -d redis redis-server /etc/redis/redis.conf \ --appendonly yes
Step 3: check the redis service role
Start the three clients, log in to the three redis container services respectively, and view the roles through the info command. By default, the three newly started redis service roles are master
127.0.0.1:6379> info replication
\# Replication role:master connected_slaves:0 master_repl_offset:3860 repl_backlog_active:1 repl_backlog_size:1048576 repl_backlog_first_byte_offset:2 repl_backlog_histlen:3859
Step 4: check the ip settings of redis6379
docker inspect redis6379
......
"Networks": {
"bridge": {
"IPAMConfig": null,
"Links": null,
"Aliases": null,
"NetworkID": "c33071765cb48acb1efed6611615c767b04b98e6e298caa0dc845420e6112b73",
"EndpointID": "4c77e3f458ea64b7fc45062c5b2b3481fa32005153b7afc211117d0f7603e154",
"Gateway": "172.17.0.1",
"IPAddress": "172.17.0.2",
"IPPrefixLen": 16,
"IPv6Gateway": "",
"GlobalIPv6Address": "",
"GlobalIPv6PrefixLen": 0,
"MacAddress": "02:42:ac:11:00:02",
"DriverOpts": null
}
}
Step 5: set Master/Slave architecture
Log in to redis6380/redis6381 respectively, and then execute the following statement
slaveof 172.17.0.2 6379
1
Note: if the master has a password, you need to add the statement "masterauth your password" in the redis.conf configuration file of the slave, restart redis, and then execute the slaveof command
Step 6: log in to redis6379 again and check info
[root@centos7964 ~]# docker exec -it redis6379 redis-cli
127.0.0.1:6379> info replication
\# Replication role:master connected_slaves:2 slave0:ip=172.17.0.3,port=6379,state=online,offset=2004,lag=1 slave1:ip=172.17.0.4,port=6379,state=online,offset=2004,lag=1 master_failover_state:no-failover master_replid:5baf174fd40e97663998abf5d8e89a51f7458488 master_replid2:0000000000000000000000000000000000000000 master_repl_offset:2004 second_repl_offset:-1 repl_backlog_active:1 repl_backlog_size:1048576 repl_backlog_first_byte_offset:1 repl_backlog_histlen:2004
Step 7: log in to redis6379 to test. The master can read and write
root@centos7964 ~]# docker exec -it redis6379 redis-cli 127.0.0.1:6379> set role master6379 OK 127.0.0.1:6379> get role "master6379" 127.0.0.1:6379>
Step 8: log in to redis6380 to test. slave can only read.
[root@centos7964 ~]# docker exec -it redis6380 redis-cli 127.0.0.1:6379> get role "master6379" 127.0.0.1:6379> set role slave6380 (error) READONLY You can't write against a read only replica. 127.0.0.1:6379>
Read / write test analysis in Java. The code is as follows:
@SpringBootTest
public class MasterSlaveTests {
@Autowired
private RedisTemplate redisTemplate;
@Test
void testMasterReadWrite(){//The profile port is 6379
ValueOperations valueOperations = redisTemplate.opsForValue();
valueOperations.set("role", "master6379");
Object role = valueOperations.get("role");
System.out.println(role);
}
@Test
void testSlaveRead(){//The profile port is 6380
ValueOperations valueOperations = redisTemplate.opsForValue();
Object role = valueOperations.get("role");
System.out.println(role);
}
}
Redis and sentinel
Sentry quick start
Step 1: enter the three redis containers respectively for configuration, and create sentinel.conf file in the specified directory of the container / etc/redis. The file content is:
sentinel monitor redis6379 172.17.0.2 6379 1
Among them, the above instruction indicates the master to be monitored, redis6379 is the service name, 172.17.0.2 and 6379 are the ip and port of the master, and 1 indicates how many sentinel s think a master is invalid
If bash: vi: command not found appears here, the following two instructions can be executed in sequence
apt-get update apt-get install vim
Step 2: execute the following instructions in the / etc/redis directory inside each redis container (preferably in multiple client windows) to start the sentinel service
redis-sentinel sentinel.conf
Step 3: open a new client connection window and close redis6379 service (this service is the master service)
docker stop redis6379
Other client windows to detect log output, such as
410:X 11 Jul 2021 09:54:27.383 # +switch-master redis6379 172.17.0.2 6379 172.17.0.4 6379 410:X 11 Jul 2021 09:54:27.383 * +slave slave 172.17.0.3:6379 172.17.0.3 6379 @ redis6379 172.17.0.4 6379 410:X 11 Jul 2021 09:54:27.383 * +slave slave 172.17.0.2:6379 172.17.0.2 6379 @ redis6379 172.17.0.4 6379
Step 4: log in to the corresponding service with ip 172.17.0.4 for info detection, for example:
127.0.0.1:6379> info replication
\# Replication role:master connected_slaves:1 slave0:ip=172.17.0.3,port=6379,state=online,offset=222807,lag=0 master_failover_state:no-failover master_replid:3d63e8474dd7bcb282ff38027d4a78c413cede53 master_replid2:5baf174fd40e97663998abf5d8e89a51f7458488 master_repl_offset:222807 second_repl_offset:110197 repl_backlog_active:1 repl_backlog_size:1048576 repl_backlog_first_byte_offset:29 repl_backlog_histlen:222779
From the above information output, it is found that the redis6381 service has now become a master.
Sentinel configuration advanced
For the contents in sentinel.conf file, we can also perform enhanced configuration based on actual requirements, such as:
sentinel monitor redis6379 172.17.0.2 6379 1 daemonize yes #Background operation logfile "/var/log/sentinel_log.log" #Run log sentinel down-after-milliseconds redis6379 30000 #Default 30 seconds
Of which:
1) Daemon yes indicates background operation (no by default)
2)logfile is used to specify the location and name of the log file
3) Sentinel down after milliseconds indicates how long it takes for the master to fail
Analysis of sentry working principle
1) : each Sentinel sends a PING command to its known Master, Slave and other Sentinel instances once a second.
2) : if the time of an instance from the last valid reply to the PING command exceeds the value specified by the down after milliseconds option (this configuration item specifies the required expiration time, a master will be subjectively considered unavailable by the Sentinel. The unit is milliseconds, and the default is 30 seconds), Then this instance will be marked as subjective offline by Sentinel.
3) : if a Master is marked as subjective offline, all sentinels monitoring the Master should confirm that the Master has indeed entered the subjective offline state once per second.
4) : when a sufficient number of sentinels (greater than or equal to the value specified in the configuration file) confirm that the Master has indeed entered the subjective offline state within the specified time range, the Master will be marked as objective offline.
5) : in general, each Sentinel will send INFO commands to all known masters and Slave every 10 seconds.
6) : when the Master is marked as objectively offline by Sentinel, the frequency of Sentinel sending INFO commands to all Slave of the offline Master will be changed from once in 10 seconds to once per second.
7) : if not enough Sentinel agree that the Master has been offline, the objective offline status of the Master will be removed.
8) : if the Master returns a valid reply to Sentinel's PING command again, the Master's subjective offline status will be removed.
Redis cluster high availability
sketch
The reliability guarantee of redis single machine mode is not very good, and it is prone to single point of failure. At the same time, its performance is also limited by the processing capacity of CPU. Redis must be highly available in actual development, so the single machine mode is not our destination. We need to upgrade the current redis architecture mode.
Sentinel mode achieves high availability, but only one master is providing services in essence (in the case of read-write separation, the master is also providing services in essence). When the machine memory of the master node is insufficient to support the system data, the cluster needs to be considered.
Redis cluster architecture realizes the horizontal expansion of redis, that is, start n redis nodes, distribute and store the whole data in the n redis nodes, and each node stores 1/N of the total data. Redis cluster provides a certain degree of availability through partition. Even if some nodes in the cluster fail or cannot communicate, the cluster can continue to process command requests.
Basic architecture
For a redis cluster, it is generally set to at least 6 nodes, 3 masters and 3 slave. Its simple architecture is as follows:
Insert picture description here
Create cluster
Step 1: prepare the network environment
The creation of virtual network card is mainly used for redis cluster to communicate with the outside world. Generally, the bridge mode is commonly used.
docker network create redis-net
To view the network card information of docker, you can use the following instructions
docker network ls
To view docker network details, you can use the command
docker network inspect redis-net
Step 2: prepare redis configuration template
mkdir -p /usr/local/docker/redis-cluster
cd /usr/local/docker/redis-cluster
vim redis-cluster.tmpl
Enter the following in redis-cluster.tmpl
port ${PORT}
cluster-enabled yes
cluster-config-file nodes.conf
cluster-node-timeout 5000
cluster-announce-ip 192.168.227.131
cluster-announce-port ${PORT}
cluster-announce-bus-port 1${PORT}
appendonly yes
Of which:
Each node is explained as follows:
Port: node port, that is, the port that provides external communication
Cluster enabled: whether to enable the cluster
Cluster config file: cluster configuration file
Cluster node timeout: connection timeout
Cluster announcement ip: host ip
Cluster announcement port: cluster node mapping port
Cluster announcement bus port: cluster bus port
appendonly: persistent mode
Step 3: create a node profile
Execute the following command in redis cluser
for port in $(seq 8010 8015); \
do \
mkdir -p ./${port}/conf \
&& PORT=${port} envsubst < ./redis-cluster.tmpl > ./${port}/conf/redis.conf \
&& mkdir -p ./${port}/data; \
done
Of which:
for variable in $(seq var1 var2);do ...; done by linux One of shell Loop script, For example: [root@centos7964 ~]# for i in $(seq 1 5);
do echo $i; done;
[root@centos7964 ~]#
The instruction envsubst < source file > target file is used to update the contents of the source file into the target file
View the contents of the configuration file through the cat instruction
cat /usr/local/docker/redis-cluster/801{0..5}/conf/redis.conf
Step 4: create a redis node container in the cluster
for port in $(seq 8010 8015); \
do \
docker run -it -d -p ${port}:${port} -p 1${port}:1${port} \
--privileged=true -v /usr/local/docker/redis-cluster/${port}/conf/redis.conf:/usr/local/etc/redis/redis.conf \
--privileged=true -v /usr/local/docker/redis-cluster/${port}/data:/data \
--restart always --name redis-${port} --net redis-net \
--sysctl net.core.somaxconn=1024 redis redis-server /usr/local/etc/redis/redis.conf; \
done
Where, -- privileged=true means that the container user to be started has true root permission, -- sysctl net.core.somaxconn=1024, which is a linux kernel parameter used to set the size of the request queue. The default value is 128. Subsequent instructions to start redis need to be placed in the request queue first, and then started in turn
After the creation is successful, view the node content through the docker ps instruction.
Step 5: create redis cluster configuration
docker exec -it redis-8010 bash
redis-cli --cluster create 192.168.227.131:8010 192.168.227.131:8011 192.168.227.131:8012 192.168.227.131:8013 192.168.227.131:8014 192.168.227.131:8015 --cluster-replicas 1
The above instructions should be executed in one line as far as possible, and the last 1 represents the master-slave ratio. When the selection prompt message appears, enter yes.
Step 6: connect the redis cluster and add data to redis
redis-cli -c -h 192.168.227.131 -p 8010
other:
During the build process, you may need to stop or directly delete the docker container after a problem occurs. You can use the following reference commands
Batch stop docker container:
docker ps -a | grep -i "redis-801*" | awk '{print $1}' | xargs docker stop
Batch delete docker container:
docker ps -a | grep -i "redis-801*" | awk '{print $1}' | xargs docker rm -f
Batch delete files
rm -rf 801{0..5}/conf/redis.conf
Jedis read / write data test
@Test
void testJedisCluster()throws Exception{
Set<HostAndPort> nodes = new HashSet<>();
nodes.add(new HostAndPort("192.168.227.131",8010));
nodes.add(new HostAndPort("192.168.227.131",8011));
nodes.add(new HostAndPort("192.168.227.131",8012));
nodes.add(new HostAndPort("192.168.227.131",8013));
nodes.add(new HostAndPort("192.168.227.131",8014));
nodes.add(new HostAndPort("192.168.227.131",8015));
JedisCluster jedisCluster = new JedisCluster(nodes);
//redis using jedisCluster
jedisCluster.set("test", "cluster");
String str = jedisCluster.get("test");
System.out.println(str);
//Close connection pool
jedisCluster.close();
}
RedisTemplate read / write data test
Step 1: configure application.yml, for example:
spring:
redis:
cluster: #redis cluster configuration
nodes: 192.168.126.128:8010,192.168.126.128:8011,192.168.126.128:8012,192.168.126.128:8013,192.168.126.128:8014,192.168.126.128:8015
max-redirects: 3 #Maximum number of jumps
timeout: 5000 #Timeout
database: 0
jedis: #Connection pool
pool:
max-idle: 8
max-wait: 0
Step 2: write the unit test class. The code is as follows:
package com.cy.redis;
@SpringBootTest
public class RedisClusterTests {
@Autowired
private RedisTemplate redisTemplate;
@Test
void testMasterReadWrite(){
//1. Get data operation object
ValueOperations valueOperations = redisTemplate.opsForValue();
//2. Read and write data
valueOperations.set("city","beijing");
Object city=valueOperations.get("city");
System.out.println(city);
}
}