Microservice Hackathon

Welcome to the Microservice Hackathon!

Here you find all information required for you to work during the Microservice Hackathon.

Table of contents

Documentation

Good to do before the workshop

If you don't know anything about Spring / Guava / Concurrency

Presentations and introductions

Additional links

Useful snippets / info

Spring Rest Controller example

Example of a Controller with an endpoint at URL /video that accepts the content-type header equal to application/vnd.some.service.v1+json and produces a JSON as output. You have to call it via POST HTTP method

@RestController
@RequestMapping(value = "/video", consumes = "application/vnd.some.service.v1+json", produces = MediaType.APPLICATION_JSON_VALUE)
public class SomeController {

    private final VideoService videoService;

    @Autowired
    public SomeController(VideoService videoService) {
        this.videoService = videoService;
    }

    @RequestMapping(method = RequestMethod.POST)
    public Videos doSomeFancyStuff(@RequestBody SomeRequestBody someRequestBody) {
        return videoService.doSomethingAwesome(someRequestBody);
    }
}

Service Rest Client example

Example of a component registered via @Component (you should use @Configuration to register beans) that uses ServiceRestClient to call other components.

import com.netflix.hystrix.HystrixCommand;
import com.nurkiewicz.asyncretry.RetryExecutor;
import com.ofg.infrastructure.web.resttemplate.fluent.ServiceRestClient;
import com.netflix.hystrix.HystrixCommand;

import static com.netflix.hystrix.HystrixCommandGroupKey.Factory.asKey;

@Component
public class VideoService {

    private final ServiceRestClient serviceRestClient;
    private final RetryExecutor retryExecutor;

    @Autowired
    public VideoService(ServiceRestClient serviceRestClient, RetryExecutor retryExecutor) {
        this.serviceRestClient = serviceRestClient;
        this.retryExecutor = retryExecutor;
    }

    public ListenableFuture<Videos> doSomethingAwesome(Ingredients ingredients) {
        return serviceRestClient.forService("someAliasFromMicroserviceDescriptor")
                .retryUsing(retryExecutor)
                .post()
                .withCircuitBreaker(HystrixCommand.Setter.withGroupKey(asKey("hystrix_group")))
                .onUrl("/someUrlToWhichYouWantToSendARequest")
                .body(ingredients)
                .withHeaders().contentType("application/vnd.some.other.service.v1+json")
                .andExecuteFor()
                .anObject()
                .ofTypeAsync(Videos.class)
    }
}

Metrics setup example

@Component
class IngredientsAggregator {

    private final SomeService someService; 
    private final Meter someMeter;

    @Autowired
    IngredientsAggregator(MetricRegistry metricRegistry,  SomeService someService) {
        this.someService = someService;
        this.someMeter = metricRegistry.meter("name.of.a.meter.metric");
        setupMeters(metricRegistry);
    }

    private void setupMeters(MetricRegistry metricRegistry) {
        metricRegistry.register("name.of.the.gauge.metric", (Gauge<Integer>) () -> someService.getValueForGauge());
    }

    public void doSomethingMeaningful(long sample) {
        // do something and mark the metric
        someMeter.mark(sample);
        // do something else
    }

}

How to take current CorrelationID

Use the following snippet

import com.ofg.infrastructure.correlationid.CorrelationIdHolder;


CorrelationIdHolder.get();

How to configure alerting in Seyren

In order to add alerting in Seyren you have to first:

Now do the following actions:

Go to checks

Click the Checks button to the top:

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Create a new check

In the checks site you will have a list of already created checks.

Click the Create check button to the top right:

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Fill out the dialog

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Here you have a description of the fields.

Add subscription

Once you've added a metric most likely you want to get notified if some threshold has been reached. To do that you have to add a subscription:

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Fill out the subscription dialog

Pick Slack as Type and type in the _channel name with a hash at the beginning. e.g.#channel`

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How to start in dev mode

To start it's enough to run the following Gradle Command

./gradlew bootRun -Dspring.profiles.active=DEV -DAPP_ENV=dev

Working example of the whole setup

Link to the Github organization with proper setup

Tools

Microservices addresses

aggregatr.io (port 9090) Swagger Jenkins
butelkatr.io (port 9091) Swagger Jenkins
dojrzewatr.io (port 9092) Swagger Jenkins
prezentatr.io (port 9093) Swagger Jenkins