Acme-Service

This is an example of a microservice.

At this level, you're at the point at which something is at its best or most highly developed.

Structure

This service contains:

1- Eureka client, to register to the server

2- Spring config, using git

To consume configuration from, the config-server in the acme-service:

• We add the Client Config starter in the pom.xml

    <dependency>
        <groupId>org.springframework.cloud</groupId>
        <artifactId>spring-cloud-starter-config</artifactId>
    </dependency>
  

• We specify the client’s app name and the location of the Config in bootstrap.yml

• You can see a greeting sample from config file exposed here :

http://localhost:8010/config/greeting

• The config is not updated (refreshed) by default on push, you need to activate the refresh option with @RefreshScope annotation.

Refresh scope beans are lazy proxies that initialize when they are used (i.e. when a method is called), and the scope acts as a cache of initialized values. To force a bean to re-initialize on the next method call you just need to invalidate its cache entry.

The RefreshScope is a bean in the context and it has a public method refreshAll() to refresh all beans in the scope by clearing the target cache. There is also a refresh(String) method to refresh an individual bean by name. This functionality is exposed in the /refresh endpoint (over HTTP or JMX).

• Then we should POST with curl -d {} http://localhost:8010/refresh to trigger refresh.

• If you want toa Auto refreshing the properties on client, use @EnableScheduled IN your application to call RefreshEndpoint.refresh() directly in java code. (See more here : #138 , #186)

3- REST services endpoints with Hystrix circuit breaker (and stream for monitoring)

http://localhost:8010/?app=acme-service

http://localhost:8010/greeting/akram

http://localhost:8003/api/acme-service/greeting/akram

ab -n 10000 -c 50 http://localhost:8003/api/acme-service/unsafe/greeting/ffff?failureProbability=0.7

4- Tracing (sleuth)

You can see in the logs:

INFO [acme-service,15d08f544834bcfc,15d08f544834bcfc,false] 7996 --- [nio-8010-exec-1] c.t.l.s.m.s.a.rest.GreetingController : you called for safe greeting

5- Api documentation (Swagger2)

The REST APi documentation in this example is based on swagger v2 which is based on OpenAPI Specification and generated a swagger.json endpoint here:

http://localhost:8010/api-docs

You can change the spec path in application.yml :

springfox: 
  documentation: 
    swagger: 
      v2: 
        path: /api/docs

• Configuration

The configuration in SwaggerConfig.java mainly centers around the Docket bean. It makes, through using any(), documentation for your entire API available through Swagger. * (NB: this is only for demo and should be changed)*

Minimal config:

 @Configuration
 @EnableSwagger2
 public class SwaggerConfig {
     @Bean
     public Docket api() {
         return new Docket(DocumentationType.SWAGGER_2)
                 .select()
                 .apis(RequestHandlerSelectors.any())
                 .paths(PathSelectors.any())
                 .build();
     }
 }

NB: you need to enable CORS to be able to parse and call spec from another swagger-ui server, but only for dev environment (see CORSFilter.java)

• Tuning

https://jakubstas.com/spring-jersey-swagger-fine-tuning-exposed-documentation/#.WPoZ19LyhPY

References

http://swagger-spring-boot.blogspot.fr/

http://www.baeldung.com/swagger-2-documentation-for-spring-rest-api

https://andressanchezblog.wordpress.com/2016/09/15/refresh-scope-in-spring-cloud/