Sentinel/sentinel-adapter/sentinel-zuul-adapter/README.md

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# Sentinel Zuul Adapter
Zuul does not provide rateLimit function, If 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 zuul gateway service.
*Note*: this project is for zuul 1.
## How to use
1. Add maven dependency
```xml
<dependency>
<groupId>com.alibaba.csp</groupId>
<artifactId>sentinel-zuul-adapter</artifactId>
<version>x.y.z</version>
</dependency>
```
2. Register filters
```java
// get registry
final FilterRegistry r = FilterRegistry.instance();
// this is property config. set filter ennable
SentinelZuulProperties properties = new SentinelZuulProperties();
properties.setEnabled(true);
// set url cleaner, here use default
DefaultUrlCleaner defaultUrlCleaner = new DefaultUrlCleaner();
// set origin parser. here use default
DefaultRequestOriginParser defaultRequestOriginParser = new DefaultRequestOriginParser();
// register filters. you must register all three filters.
SentinelPreFilter sentinelPreFilter = new SentinelPreFilter(properties, defaultUrlCleaner, defaultRequestOriginParser);
r.put("sentinelPreFilter", sentinelPreFilter);
SentinelPostFilter postFilter = new SentinelPostFilter(properties);
r.put("sentinelPostFilter", postFilter);
SentinelErrorFilter errorFilter = new SentinelErrorFilter(properties);
r.put("sentinelErrorFilter", errorFilter);
```
## How it works
As Zuul run as per thread per connection block model, we add filters around `route Filter` to trace sentinel statistics.
- `SentinelPreFilter`: Get an entry of resource,the first order is **ServiceId**(the key in RequestContext is `serviceId`, this can set in own custom filter), then **API Path**.
- `SentinelPostFilter`: When success response,exit entry.
- `SentinelPreFilter`: When get an `Exception`, trace the exception and exit context.
the order of Filter can be changed in property:
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/coke(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/coke(t:0 pq:0 bq:0 tq:0 rt:0 prq:0 1mp:0 1mb:0 1mt:0)
```
`book` and `coke` are serviceId.
`---/book/coke` is api path, the real uri is `/coke`.
## Integration with Sentinel DashBord
1. Start [Sentinel DashBord](https://github.com/alibaba/Sentinel/wiki/%E6%8E%A7%E5%88%B6%E5%8F%B0).
2. Sentinel has full rule config features. see [Dynamic-Rule-Configuration](https://github.com/alibaba/Sentinel/wiki/Dynamic-Rule-Configuration)
## Fallbacks
Implements `SentinelFallbackProvider` to define your own Fallback Provider when Sentinel Block Exception throwing. the default
Fallback Provider is `DefaultBlockFallbackProvider`.
By default Fallback route is `ServiveId + URI PATH`, example `/book/coke`, first `book` is serviceId, `/coke` is URI PATH. so that both
can be needed.
Here is an example:
```java
// custom provider
public class MyBlockFallbackProvider implements ZuulBlockFallbackProvider {
private Logger logger = LoggerFactory.getLogger(DefaultBlockFallbackProvider.class);
// you can define root as service level
@Override
public String getRoute() {
return "/coke/coke";
}
@Override
public BlockResponse fallbackResponse(String route, Throwable cause) {
RecordLog.info(String.format("[Sentinel DefaultBlockFallbackProvider] Run fallback route: %s", route));
if (cause instanceof BlockException) {
return new BlockResponse(429, "Sentinel block exception", route);
} else {
return new BlockResponse(500, "System Error", route);
}
}
}
// register fallback
ZuulBlockFallbackManager.registerProvider(new MyBlockFallbackProvider());
```
Default block response
```json
{
"code":429,
"message":"Sentinel block exception",
"route":"/"
}
```
## Origin parser
自定义解析URL
```java
public class DefaultRequestOriginParser implements RequestOriginParser {
@Override
public String parseOrigin(HttpServletRequest request) {
return "";
}
}
```