sl-express/sentinel/sentinel-adapter/sentinel-zuul-adapter

Sentinel Zuul Adapter

Sentinel Zuul Adapter provides route level and customized API level flow control for Zuul API Gateway.

Note: this adapter only support Zuul 1.x.

How to use

1. Add Maven dependency to your pom.xml:

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-zuul-adapter</artifactId>
    <version>x.y.z</version>
</dependency>

2. Register filters

For Spring Cloud Zuul users, we only need to inject the three filters in Spring configuration class like this:

@Configuration
public class ZuulConfig {

    @Bean
    public ZuulFilter sentinelZuulPreFilter() {
        // We can provider the filter order here.
        return new SentinelZuulPreFilter(10000);
    }

    @Bean
    public ZuulFilter sentinelZuulPostFilter() {
        return new SentinelZuulPostFilter(1000);
    }

    @Bean
    public ZuulFilter sentinelZuulErrorFilter() {
        return new SentinelZuulErrorFilter(-1);
    }
}

For original Zuul users:

// Get filter registry
final FilterRegistry r = FilterRegistry.instance();

// We need to register all three filters.
SentinelZuulPreFilter sentinelPreFilter = new SentinelZuulPreFilter();
r.put("sentinelZuulPreFilter", sentinelPreFilter);
SentinelZuulPostFilter postFilter = new SentinelZuulPostFilter();
r.put("sentinelZuulPostFilter", postFilter);
SentinelZuulErrorFilter errorFilter = new SentinelZuulErrorFilter();
r.put("sentinelZuulErrorFilter", errorFilter);

How it works

As Zuul run as per thread per connection block model, we add filters around route filter to trace Sentinel statistics.

• SentinelZuulPreFilter: This pre-filter will regard all proxy ID (proxy in RequestContext) and all customized API as resources. When a BlockException caught, the filter will try to find a fallback to execute.
• SentinelZuulPostFilter: When the response has no exception caught, the post filter will complete the entries.
• SentinelZuulErrorFilter: When an exception is caught, the filter will trace the exception and complete the entries.

The order of filters can be changed via the constructor.

The invocation chain resembles this:

-EntranceNode: sentinel_gateway_context$$route$$another-route-b(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:8 1mb:1 1mt:9)
--another-route-b(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:4 1mb:1 1mt:5)
--another_customized_api(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:4 1mb:0 1mt:4)
-EntranceNode: sentinel_gateway_context$$route$$my-route-1(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:6 1mb:0 1mt:6)
--my-route-1(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:2 1mb:0 1mt:2)
--some_customized_api(t:0 pq:0.0 bq:0.0 tq:0.0 rt:0.0 prq:0.0 1mp:2 1mb:0 1mt:2)

Integration with Sentinel Dashboard

1. Start Sentinel Dashboard.
2. You can configure the rules in Sentinel dashboard or via dynamic rule configuration.

Fallbacks

You can implement SentinelFallbackProvider to define your own fallback provider when Sentinel BlockException is thrown. The default fallback provider is DefaultBlockFallbackProvider.

By default fallback route is proxy ID (or customized API name).

Here is an example:

// 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 "my-route";
    }

    @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:

{
    "code":429,
    "message":"Sentinel block exception",
    "route":"/"
}

Request origin parser

You can register customized request origin parser like this:

public class MyRequestOriginParser implements RequestOriginParser {
    @Override
    public String parseOrigin(HttpServletRequest request) {
        return request.getRemoteAddr();
    }
}