Master Sentinel Console: Real‑Time Monitoring, Flow Control & Rule Configuration Guide

Console Overview

Sentinel provides a lightweight open‑source console for machine discovery, health monitoring, real‑time metrics, rule management and push, as well as authentication.

Environment

jdk 1.8

sentinel 1.8.0

spring-boot 2.3.5.RELEASE

spring-cloud Hoxton.SR8

spring-cloud-alibaba 2.2.5.RELEASE

Machine List & Health

After successful integration, the

Machine List

menu displays each service node's health status.

If Sentinel integration fails, refer to the official documentation or FAQ for troubleshooting.

Service Monitoring

1. Real‑time Monitoring

Metrics from all machines under the same service are aggregated and displayed under "Real‑time Monitoring" with a 5‑minute data retention window.

Ensure the console machine time matches the application machine time, otherwise real‑time data cannot be fetched.

2. Cluster Call Chain

The cluster call chain page shows resource call relationships in two modes: a tree structure or a flat view of real‑time resource status.

Again, synchronize the console and application machine times.

3. Flow Control Rules

Flow control monitors QPS or concurrent threads and blocks traffic when thresholds are exceeded, protecting application availability.

Key slots involved:

FlowSlot

,

NodeSelectorSlot

,

ClusterBuilderSlot

,

StatisticSlot

.

When a rule is triggered,

Entry nodeA = SphU.entry(resourceName)

throws a

FlowException

, which is a subclass of

BlockException

. Custom handlers can catch

BlockException

to define fallback logic.

<code>@Component
public class SentinelBlockHandler implements BlockExceptionHandler {
    @Override
    public void handle(HttpServletRequest request, HttpServletResponse response, BlockException e) throws Exception {
        CommonResult<Void> result = new CommonResult<>();
        if (e instanceof FlowException) {
            result = CommonResult.error(101, "接口限流了");
        } else if (e instanceof DegradeException) {
            result = CommonResult.error(102, "服务降级了");
        } else if (e instanceof ParamFlowException) {
            result = CommonResult.error(103, "热点参数限流了");
        } else if (e instanceof SystemBlockException) {
            result = CommonResult.error(104, "系统规则（负载/...不满足要求）");
        } else if (e instanceof AuthorityException) {
            result = CommonResult.error(105, "授权规则不通过");
        }
        response.setStatus(500);
        response.setCharacterEncoding("utf-8");
        response.setHeader("Content-Type", "application/json;charset=utf-8");
        response.setContentType("application/json;charset=utf-8");
        new ObjectMapper().writeValue(response.getWriter(), result);
    }
}
</code>

Example curl results:

{"code":1,"message":"this is a success message","data":{"id":1,"code":"STOCK==>1000"}}
{"code":101,"message":"接口限流了","data":null}

Threshold Types

Thread Count : Limits concurrent threads to protect thread pools. Configuration is usually done on the caller side.

Flow Control Modes

Direct : Immediate rejection when QPS exceeds the threshold (default behavior).

Warm‑up : Gradually ramps up traffic to avoid sudden spikes on cold systems.

Rate Limiter : Enforces a uniform request interval using a leaky‑bucket algorithm (not supported for QPS > 1000).

4. Degrade Rules

Degrade (circuit‑breaker) protects services from unstable downstream calls. Strategies include slow‑call ratio, error ratio, and error count.

Example configuration screenshot omitted for brevity.

5. Hotspot Rules

Hotspot (parameter) flow control limits frequently accessed parameter values (e.g., hot product IDs). Resources must be annotated with

@SentinelResource

and parameters must be primitive types.

6. Authorization Rules

Origin‑based black‑/white‑list control restricts access based on the request's

origin

. Implement

RequestOriginParser

to extract the origin, then configure rules in the console.

7. System Rules

System protection monitors load, CPU usage, average RT, concurrent threads, and inbound QPS at the application entry level. Only entry traffic (

EntryType.IN

) is affected.

Supported modes: Load adaptive, CPU usage, average RT, concurrent threads, entry QPS.

8. Cluster Flow Control

Cluster flow control centralizes token distribution to enforce global QPS limits across multiple instances, solving uneven traffic distribution.

Roles: Token Client (requests tokens) and Token Server (issues tokens).

Rule Push

The console supports three push modes: raw, Pull, and Push. Rules are stored in memory by default; for production, use dynamic rule sources (e.g., Nacos, Apollo) and the push mode.

Authentication

Since Sentinel 1.5.0, a generic

AuthService

interface allows custom authentication. From 1.6.0, a basic login (default user/password:

sentinel

) is provided, configurable via JVM arguments or Spring properties.

Reference

Official documentation: https://github.com/alibaba/Sentinel/wiki/控制台