# Sentinel Spring Cloud Zuul Adapter
Zuul does not provide rateLimit function, If you use default `SentinelRibbonFilter` route filter. it wrapped by Hystrix Command. so only provide Service level
circuit protect.
Sentinel can provide `ServiceId` level and `API Path` level flow control for spring cloud zuul gateway service.
*Note*: this project is for zuul 1.
## How to use
1. Add maven dependency
```xml
< dependency >
< groupId > com.alibaba.cloud< / groupId >
< artifactId > spring-cloud-alibaba-sentinel-gateway< / artifactId >
< version > x.y.z< / version >
< / dependency >
```
2. Set application.property
```
// default value is false
spring.cloud.sentinel.zuul.enabled=true
```
## How it works
As Zuul run as per thread connection block model, we add filters around `route Filter` to trace sentinel statistics.
- `SentinelPreFilter` : Get an entry of resource,the first order is **ServiceId** , then **API Path** .
- `SentinelPostFilter` : When success response,exit entry.
- `SentinelErrorFilter` : When get an `Exception` , trace the exception and exit context.
the order of Filter can be changed by configuration:
```
spring.cloud.sentinel.zuul.order.post=0
spring.cloud.sentinel.zuul.order.pre=10000
spring.cloud.sentinel.zuul.order.error=-1
```
Filters create structure like:
```bash
EntranceNode: machine-root(t:3 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
-EntranceNode: coke(t:2 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
--coke(t:2 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
---/coke/uri(t:0 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
-EntranceNode: sentinel_default_context(t:0 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
-EntranceNode: book(t:1 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
--book(t:1 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
---/book/uri(t:0 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
```
`book` and `coke` are serviceId.
`---/book/uri` is api path, the real uri is `/uri` .
## Integration with Sentinel DashBord
Start [Sentinel DashBord ](https://github.com/alibaba/Sentinel/wiki/%E6%8E%A7%E5%88%B6%E5%8F%B0 ).
## Rule config with dataSource
Sentinel has full rule config features. see [Dynamic-Rule-Configuration ](https://github.com/alibaba/Sentinel/wiki/Dynamic-Rule-Configuration )
## Custom Fallbacks
Implements `SentinelFallbackProvider` to define your own Fallback Provider when Sentinel Block Exception throwing for different rout. the default
Fallback Provider is `DefaultBlockFallbackProvider` .
By default, fallback route is `ServiveId + URI PATH` , example `/book/coke` , first `book` is serviceId, `/uri` is URI PATH, so both
can be needed.
Here is an example:
```java
// custom provider
public class MyCokeServiceBlockFallbackProvider implements SentinelFallbackProvider {
private Logger logger = LoggerFactory.getLogger(DefaultBlockFallbackProvider.class);
// you can define root as service level
@Override
public String getRoute() {
return "/coke/uri";
}
@Override
public ClientHttpResponse fallbackResponse(String route, Throwable cause) {
if (cause instanceof BlockException) {
logger.info("get in fallback block exception:{}", cause);
return response(HttpStatus.TOO_MANY_REQUESTS, route);
} else {
return response(HttpStatus.INTERNAL_SERVER_ERROR, route);
}
}
}
```
## Custom Request Origin Parser
By default, this adapter use `DefaultRequestOriginParser` to parse sentinel origin.
```java
public class CustomRequestOriginParser implements RequestOriginParser {
@Override
public String parseOrigin(HttpServletRequest request) {
// do custom logic.
return "";
}
}
```
## Custom UrlCleaner
By default this adapter use `DefaultUrlCleaner` to define uri resource.
```java
public class CustomUrlCleaner implements UrlCleaner {
@Override
public String clean(String originUrl) {
// do custom logic.
return originUrl;
}
}
```
