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Table of Contents

Micronaut Netflix

Integration between Micronaut and Netflix OSS

Version:

1 Introduction

This project features integrations between Netflix OSS and Micronaut.

Release History

  • Micronaut 1.3.0 Minimum Version

  • Upgrade to Hystrix 1.5.18

  • Upgrade to Ribbon 2.7.17

1.0.0

  • Initial Version

2 Hystrix Support

Using the CLI

If you are creating your project using the Micronaut CLI, supply the netflix-hystrix feature to configure Hystrix in your project:

$ mn create-app my-app --features netflix-hystrix

Netflix Hystrix is a fault tolerance library developed by the Netflix team and designed to improve resilience of inter process communication.

Micronaut features integration with Hystrix through the netflix-hystrix module, which you can add to your build.gradle or pom.xml:

implementation("io.micronaut.configuration:micronaut-netflix-hystrix")
<dependency>
    <groupId>io.micronaut.configuration</groupId>
    <artifactId>micronaut-netflix-hystrix</artifactId>
</dependency>

Using the @HystrixCommand Annotation

With the above dependency declared you can annotate any method (including methods defined on @Client interfaces) with the @HystrixCommand annotation and it will wrap the methods execution in a Hystrix command. For example:

Using @HystrixCommand
@HystrixCommand
String hello(String name) {
    return "Hello $name"
}
This works for reactive return types such as Flowable etc. as well and the reactive type will be wrapped in a HystrixObservableCommand.

The @HystrixCommand annotation also integrates with Micronauts support for Retry Advice and Fallbacks

For information on how to customize the Hystrix thread pool, group and properties see the javadoc for @HystrixCommand.

Enabling Hystrix Stream & Dashboard

You can enable a Server Sent Event stream to feed into the Hystrix Dashboard by setting the hystrix.stream.enabled setting to true in application.yml:

Enabling Hystrix Stream
hystrix:
    stream:
        enabled: true

This exposes a /hystrix.stream endpoint with the format the Hystrix Dashboard expects.

3 Ribbon Support

Using the CLI

If you are creating your project using the Micronaut CLI, supply the netflix-ribbon feature to configure Netflix Ribbon in your project:

$ mn create-app my-app --features netflix-ribbon

Netflix Ribbon is a inter-process communication library used at Netflix that has support for customizable load balancing strategies.

If you need more flexibility in how your application performs client-side load balancing then you may wish use Micronaut’s Netflix Ribbon support.

To add Ribbon support to your application add the netflix-ribbon configuration to build.gradle or pom.xml:

implementation("io.micronaut.configuration:micronaut-netflix-ribbon")
<dependency>
    <groupId>io.micronaut.configuration</groupId>
    <artifactId>micronaut-netflix-ribbon</artifactId>
</dependency>

The LoadBalancer implementations will now be RibbonLoadBalancer instances.

Ribbon’s Configuration options can be set using the ribbon namespace in configuration. For example in application.yml:

Configuring Ribbon
ribbon:
    VipAddress: test
    ServerListRefreshInterval: 2000

Each discovered client can also be configured under ribbon.clients. For example given a @Client(id = "hello-world") you can configure Ribbon settings with:

Per Client Ribbon Settings
ribbon:
    clients:
        hello-world:
            VipAddress: test
            ServerListRefreshInterval: 2000

By default Micronaut registers a DiscoveryClientServerList for each client that integrates Ribbon with Micronaut’s DiscoveryClient.

4 Repository

You can find the source code of this project in this repository:

https://github.com/micronaut-projects/micronaut-netflix