sl-express/sentinel/sentinel-extension/sentinel-datasource-redis/README.md
shuhongfan cf5ac25c14 init
2023-09-04 16:40:17 +08:00

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# Sentinel DataSource Redis
Sentinel DataSource Redis provides integration with Redis. The data source leverages Redis pub-sub feature to implement push model (listener).
The data source uses [Lettuce](https://lettuce.io/) as the Redis client, which requires JDK 1.8 or later.
> **NOTE**: Currently we do not support Redis Cluster now.
## Usage
To use Sentinel DataSource Redis, you should add the following dependency:
```xml
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-datasource-redis</artifactId>
<version>x.y.z</version>
</dependency>
```
Then you can create an `RedisDataSource` and register to rule managers.
For instance:
```java
ReadableDataSource<String, List<FlowRule>> redisDataSource = new RedisDataSource<List<FlowRule>>(redisConnectionConfig, ruleKey, channel, flowConfigParser);
FlowRuleManager.register2Property(redisDataSource.getProperty());
```
- `redisConnectionConfig`: use `RedisConnectionConfig` class to build your Redis connection config
- `ruleKey`: the rule persistence key of a Redis String
- `channel`: the channel to subscribe
You can also create multi data sources to subscribe for different rule type.
Note that the data source first loads initial rules from a Redis String (provided `ruleKey`) during initialization.
So for consistency, users should publish the value and save the value to the `ruleKey` simultaneously like this (using Redis transaction):
```
MULTI
SET ruleKey value
PUBLISH channel value
EXEC
```
An example using Lettuce Redis client:
```java
public <T> void pushRules(List<T> rules, Converter<List<T>, String> encoder) {
StatefulRedisPubSubConnection<String, String> connection = client.connectPubSub();
RedisPubSubCommands<String, String> subCommands = connection.sync();
String value = encoder.convert(rules);
subCommands.multi();
subCommands.set(ruleKey, value);
subCommands.publish(ruleChannel, value);
subCommands.exec();
}
```
Transaction can be handled in Redis Cluster when just using the same key.
An example using Lettuce Redis Cluster client:
```java
public <T> void pushRules(List<T> rules, Converter<List<T>, String> encoder) {
RedisAdvancedClusterCommands<String, String> subCommands = client.connect().sync();
int slot = SlotHash.getSlot(ruleKey);
NodeSelection<String, String> nodes = subCommands.nodes((n)->n.hasSlot(slot));
RedisCommands<String, String> commands = nodes.commands(0);
String value = encoder.convert(rules);
commands.multi();
commands.set(ruleKey, value);
commands.publish(channel, value);
commands.exec();
}
```
## How to build RedisConnectionConfig
### Build with Redis standalone mode
```java
RedisConnectionConfig config = RedisConnectionConfig.builder()
.withHost("localhost")
.withPort(6379)
.withPassword("pwd")
.withDataBase(2)
.build();
```
### Build with Redis Sentinel mode
```java
RedisConnectionConfig config = RedisConnectionConfig.builder()
.withRedisSentinel("redisSentinelServer1",5000)
.withRedisSentinel("redisSentinelServer2",5001)
.withRedisSentinelMasterId("redisSentinelMasterId").build();
```
### Build with Redis Cluster mode
```java
RedisConnectionConfig config = RedisConnectionConfig.builder()
.withRedisCluster("redisSentinelServer1",5000)
.withRedisCluster("redisSentinelServer2",5001).build();
```