README

说明

该版本根据piwvh/php-eureka稍作配置上的优化而来。

使用说明

安装

使用composer依赖管理工具进行安装即可；

composer require "yckj/eureka_php"

使用

该组件基本未改变原始用法，仅作了添加日志的操作。可参见原作者piwvh/php-eureka

Create Eureka Client

The very first thing you should do is to create an instance of EurekaClient using your configuration:

$client = new EurekaClient([
    'eurekaDefaultUrl' => 'http://localhost:8761/eureka',
    'hostName' => 'service.hamid.work',
    'appName' => 'service',
    'ip' => '127.0.0.1',
    'port' => ['8080', true],
    'homePageUrl' => 'http://localhost:8080',
    'statusPageUrl' => 'http://localhost:8080/info',
    'healthCheckUrl' => 'http://localhost:8080/health'
]);

List of all available configuration includes:

eurekaDefaultUrl (default: http://localhost:8761);
hostName
appName
ip
status (default: UP)
overriddenStatus (default: UNKNOWN)
port
securePort (default: ['443', false])
countryId (default: 1)
dataCenterInfo (default: ['com.netflix.appinfo.InstanceInfo$DefaultDataCenterInfo', 'MyOwn'])
homePageUrl
statusPageUrl
healthCheckUrl
vipAddress
secureVipAddress
heartbeatInterval (default: 30)
discoveryStrategy (default: RandomStrategy)
instanceProvider

You can also change configuration after creating EurekaClient instance, using setter methods:

$client->getConfig()->setAppName("my-service");

Operations

After creating EurekaClient instance, there will be multiple operations you can do:

Registration: register your service instance with Eureka

$client->register();

De-registration: de-register your service instance from Eureka

$client->deRegister();

Heartbeat: send heartbeat to Eureka, to determine the client is up (one-time heartbeat)

$client->heartbeat();

You can register your instance and sent periodic heartbeat using start() method:

$client->start();

With this method, first your service gets registered with Eureka using the configuration you have provided, then a heartbeat will be sent to the Eureka periodically based on heartbeatInterval config. This interval time can be changed just like any other configuration item:

$client->getConfig()->setHeartbeatInterval(60); // 60 seconds

Service Discovery: fetch an instance of a service from Eureka:

$instance = $client->fetchInstance("the-service");
$homePageUrl = $instance->homePageUrl;

Discovery Strategy

When fetching instances of a service from Eureka, you probably get a list of available instances registered with Eureka. You can choose one of them based on your desired strategy of load balancing. For example, a Round-robin or a Random strategy might be your choice.

Currently this library only supports RandomStrategy, but you can create your custom strategy by implementing getInstance() method of DiscoveryStrategy interface:

class RoundRobinStrategy implements DiscoveryStrategy {

    public function getInstance($instances) {
        // return an instance
    }
    
}

Then all you have to do is to introduce your custom strategy to EurekaClient instance:

$client->getConfig()->setDiscoveryStrategy(new RoundRobinStrategy());

Local Registry and Caching

As you know, failure is inevitable, specially in cloud-native or distributed applications. So, sometimes Eureka may not be available duo to the failure. In this case, we should have a local registry of services to avoid cascading failures.

In the default behaviour, if Eureka is down, the fetchInstance() method fails and so the application throws and exception and can not continue to work. To solve this problem, you should create a local registry in your application.

There is an interface called InstanceProvider which you can make use of. You should implement getInstance() method of this interface and return instances of a service based on your ideal logic.

class MyProvider implements InstanceProvider {

    public function getInstances($appName) { 
        // return cached instances of the service from the database 
    }
}

In this example, we have cached the instances of the service in the database and are retrieving them from the database when Eureka is not available.

After creating your custom provider, just make it work by adding it to the configuration:

$client->getConfig()->setInstanceProvider(new MyProvider());

Your custom provider only gets called when Eureka is down or is not answering properly.

That's it. By adding this functionality, your application continues to work even when Eureka is down.

For caching all available instances of a specific service, you can call fetchInstances() method which return all instances of a service, fetched from Eureka:

$instances = $client->fetchInstances("the-service");

fuermao / eureka_php

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