Sentinel: Sentinel of Your Application

Documentation

See the Wiki for full documentation, examples, operational details and other information.

See the Javadoc for the API.

See 中文Readme for readme

What Does It Do?

With the popularity of distributed systems, the stability between services is becoming more important than ever before. Sentinel takes "flow" as breakthrough point, and works on multiple fields including flow control, concurrency, circuit breaking, load protection, to protect service stability

Sentinel has following features:

• Rich applicable scenarios for flow control, concurrency, circuit breaking, load protection
• Integrated monitor, operation module,
• Easy extension point

Download Library

Example for Maven:

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

Sentinel requires Java 6 or later.

"Hello world"

Frist wrap code snippet via sentinel api: SphU.entry("RESOURCENAME") and entry.exit().

Entry entry = null;

try {   
  entry = SphU.entry("HelloWorld");
  
  // BIZ logic being protected
  System.out.println("hello world");
} catch (BlockException e) {
  // handle block logic
} finally {
  // make sure that the exit() logic is called
  if (entry != null) {
    entry.exit();
  }
}

After above steps, you can use sentinel now. By default, we will provide adapter to do this for popular frameworks.

Define Rules

    List<FlowRule> rules = new ArrayList<FlowRule>();
    FlowRule rule = new FlowRule();
    rule.setResource("hello world");
    // set limit qps to 20
    rule.setCount(20);
    rules.add(rule);
    FlowRuleManager.loadRules(rules);

Result

And you can see following records in [user dir]\csp\logs\${appName}-metrics.log.xxx

|--timestamp-|------date time----|--resource-|p |block|s |e|rt
1529998904000|2018-06-26 15:41:44|hello world|20|0    |20|0|0
1529998905000|2018-06-26 15:41:45|hello world|20|5579 |20|0|728
1529998906000|2018-06-26 15:41:46|hello world|20|15698|20|0|0
1529998907000|2018-06-26 15:41:47|hello world|20|19262|20|0|0
1529998908000|2018-06-26 15:41:48|hello world|20|19502|20|0|0
1529998909000|2018-06-26 15:41:49|hello world|20|18386|20|0|0

p for incoming reqeust, block for intercepted by rules, success for success handled, e for exception, rt for average response time(ms)

More examples and information can be found in the How To Use section.

How it works can be found in How it works

Samples can be found in the demo module.

Start Dashboard

Sentinel also has a simple dashboad, which can monitor the cliets, and configure the rules.

1. Download Sentinel-Dashboard module
2. Run command to package this module:

$ mvn clean package

3. Start dashboard

$ java -Dserver.port=8080 \
-Dcsp.sentinel.dashboard.server=localhost:8080 \
-Dproject.name=sentinel-dashboard \
-jar target/sentinel-dashboard.jar

4. Include sentinel client in your application by mvn or download this library:

<dependency>
    <groupId>com.alibaba.csp</groupId>
    <artifactId>sentinel-transport-simple-http</artifactId>
    <version>x.y.z</version>
</dependency>

If you need to download the jars instead of using a build system, create a Maven pom file like this with the desired version:

<?xml version="1.0"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.alibaba</groupId>
    <artifactId>download-sentine</artifactId>
    <version>1.0-SNAPSHOT</version>
    <name>Simple POM to download sentinel-core and dependencies</name>
    <dependencies>
        <dependency>
            <groupId>com.alibaba.csp</groupId>
            <artifactId>sentinel-transport-simple-http</artifactId>
            <version>x.y.z</version>
            <scope/>
        </dependency>
    </dependencies>
</project>

Then execute:

mvn -f download-sentinel-pom.xml dependency:copy-dependencies

5. Add JVM parameter -Dcsp.sentinel.dashboard.server=consoleIp:port when you start your application

6. Trigger your resource

After above steps, you can check your application in "Machnes" and resources runtime infomation in your dashboard.

More details please refer to: Dashboard

Trouble Shooting and Logs

Sentinel will generate logs for trouble shooting. All the infos can be found in logs

Bugs and Feedback

For bugs, questions and discussions please use the GitHub Issues

Contact us: sentinel@linux.alibaba.com

Twitter:@AlibabaSentinel

Weibo: