Refactor @FeignClient to use name= or url= but not both
Replaces the boolean flag (loadbalance) for switching between service resolution (by name) or straight URL bashing.
This commit is contained in:
Dave Syer
@@ -425,65 +425,6 @@ On the server side Just create a Spring Boot application and annotate it with `@
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Spring Cloud provides a `spring-cloud-starter-turbine-amqp` that has all the dependencies you need to get a Turbine AMQP server running. You need Java 8 to run the app because it is Netty-based.
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[[spring-cloud-feign]]
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== Declarative REST Client: Feign
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https://github.com/Netflix/feign[Feign] is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same `HttpMessageConverters` used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.
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Example spring boot app
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[source,java,indent=0]
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----
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@Configuration
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@ComponentScan
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@EnableAutoConfiguration
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@EnableEurekaClient
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@FeignClientScan
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public class Application {
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public static void main(String[] args) {
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SpringApplication.run(Application.class, args);
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}
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}
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----
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.StoreClient.java
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[source,java,indent=0]
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----
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@FeignClient("stores")
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public interface StoreClient {
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@RequestMapping(method = RequestMethod.GET, value = "/stores")
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List<Store> getStores();
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@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
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Store update(@PathParameter("storeId") Long storeId, Store store);
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}
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----
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In the `@FeignClient` annotation the String value ("stores" above) is
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the arbitrary name of the client, used to create a configuration
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prefix (see <<spring-cloud-ribbon,below for details of Ribbon
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support>>).
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[[spring-cloud-feign-without-eureka]]
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=== Example: How to Use Feign Without Eureka
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Eureka is a convenient way to abstract the discovery of remote servers
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so you don't have to hard code their URLs in clients, but if you
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prefer not to use it, Ribbon and Feign are still quite
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amenable. Suppose you have declared a Feign client as above for
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"stores", and Eureka is not in use (and not even on the
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classpath). You should find that the Ribbon client defaults to a
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configured server list, and you can supply the configuration like this
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.application.yml
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----
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stores:
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ribbon:
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listOfServers: example.com,google.com
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----
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[[spring-cloud-ribbon]]
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== Client Side Load Balancer: Ribbon
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@@ -505,8 +446,7 @@ annotation). Spring Cloud creates a new ensemble as an
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You can configure some bits of a Ribbon client using external
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properties in `<client>.ribbon.*`, which is no different than using
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the Netflix APIs natively, except that you can use Spring Boot
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configuration files (example
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<<spring-cloud-feign-without-eureka,above>>). The native options can
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configuration files. The native options can
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be inspected as static fields in `CommonClientConfigKey` (part of
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ribbon-core).
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@@ -561,6 +501,24 @@ populates the list of servers from Eureka. It also replaces the `IPing`
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interface with `NIWSDiscoveryPing` which delegates to Eureka to determine if
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a server is up.
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[[spring-cloud-ribbon-without-eureka]]
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=== Example: How to Use Ribbon Without Eureka
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Eureka is a convenient way to abstract the discovery of remote servers
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so you don't have to hard code their URLs in clients, but if you
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prefer not to use it, Ribbon and Feign are still quite
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amenable. Suppose you have declared a `@RibbonClient` for "stores",
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and Eureka is not in use (and not even on the classpath). The Ribbon
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client defaults to a configured server list, and you can supply the
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configuration like this
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.application.yml
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----
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stores:
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ribbon:
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listOfServers: example.com,google.com
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----
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=== Using the Ribbon API Directly
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You can also use the `LoadBalancerClient` directly. Example:
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@@ -603,6 +561,55 @@ physical address. See
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{github-code}/spring-cloud-netflix-core/src/main/java/org/springframework/cloud/netflix/ribbon/RibbonAutoConfiguration.java[RibbonAutoConfiguration]
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for details of how the `RestTemplate` is set up.
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[[spring-cloud-feign]]
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== Declarative REST Client: Feign
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https://github.com/Netflix/feign[Feign] is a declarative web service client. It makes writing web service clients easier. To use Feign create an interface and annotate it. It has pluggable annotation support including Feign annotations and JAX-RS annotations. Feign also supports pluggable encoders and decoders. Spring Cloud adds support for Spring MVC annotations and for using the same `HttpMessageConverters` used by default in Spring Web. Spring Cloud integrates Ribbon and Eureka to provide a load balanced http client when using Feign.
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Example spring boot app
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[source,java,indent=0]
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----
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@Configuration
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@ComponentScan
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@EnableAutoConfiguration
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@EnableEurekaClient
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@EnableFeignClients
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public class Application {
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public static void main(String[] args) {
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SpringApplication.run(Application.class, args);
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}
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}
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----
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.StoreClient.java
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[source,java,indent=0]
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----
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@FeignClient("stores")
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public interface StoreClient {
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@RequestMapping(method = RequestMethod.GET, value = "/stores")
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List<Store> getStores();
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@RequestMapping(method = RequestMethod.POST, value = "/stores/{storeId}", consumes = "application/json")
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Store update(@PathParameter("storeId") Long storeId, Store store);
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}
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----
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In the `@FeignClient` annotation the String value ("stores" above) is
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an arbitrary client name, which is used to create a Ribbon load
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balancer (see <<spring-cloud-ribbon,below for details of Ribbon
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support>>). You can also specify a URL using the `url` attribute
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(absolute value or just a hostname).
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The Ribbon client above will want to discover the physical addresses
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for the "stores" service. If your application is a Eureka client then
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it will resolve the service in the Eureka service registry. If you
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don't want to use Eureka, you can simply configure a list of servers
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in your external configuration (see
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<<spring-cloud-ribbon-without-eureka,above for example>>).
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== External Configuration: Archaius
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https://github.com/Netflix/archaius[Archaius] is the Netflix client side configuration library. It is the library used by all of the Netflix OSS components for configuration. Archaius is an extension of the http://commons.apache.org/proper/commons-configuration[Apache Commons Configuration] project. It allows updates to configuration by either polling a source for changes or for a source to push changes to the client. Archaius uses Dynamic<Type>Property classes as handles to properties.
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