Filter services by tag in ConsulDiscoveryClient

[avthart]

It would be nice to filter services by tag using the ConsulDiscoveryClient. Sometimes you only want some specific services in your application.

[outcomes-scott-oster]

We are doing this by editing ConsulServerList.java. The getServers() method calls client.getCatalogService( this.serviceId, QueryParams.DEFAULT);
when it needs to support calling:
client.getCatalogService(this.serviceId, tags, QueryParams.DEFAULT);

This behavior change should be able to be wired in via the conditional ribbonServerList in ConsulRibbonClientConfiguration:

    @Bean
    @ConditionalOnMissingBean
    public ServerList<?> ribbonServerList(IClientConfig config) {
        ConsulServerList serverList = new ConsulServerList(client, properties);
        serverList.initWithNiwsConfig(config);
        return serverList;
    }

We ran into trouble trying to inject that replacement, in that we couldn't seem to load it at a time when IClientConfig is available, but before the conditional check in ConsulRibbonClientConfiguration.

Any pointers?

[spencergibb]

Usually that means the @Configuration for your server list is getting picked up by component scanning.

[outcomes-scott-oster]

Is this the pattern we should follow then?
https://github.com/spring-cloud-samples/tests/tree/master/ribbon-default-config/src/main/java/demo

Basically create a @configuration class (that defines the ribbonServerList method) that is not loaded via componentscan or other mechanisms, then reference it in the @RibbonClients annotation? For example:
@RibbonClients(defaultConfiguration=MyDefaultRibbonConfig.class)

I'm trying to get this working with Zuul, so I'd put that annotation on the main zuul application which has @EnableDiscoveryClient on it.

[spencergibb]

Yes, that is according to the documentation http://projects.spring.io/spring-cloud/spring-cloud.html#_customizing_the_ribbon_client

[outcomes-scott-oster]

Ok, I will give it a shot. The documentation more seemed to imply it shouldn't be componentscanned unless you wanted it to be globally used (which I am fine with):

The FooConfiguration has to be @configuration but take care that it is not in a @componentscan for the main application context, otherwise it will be shared by all the @RibbonClients.

[spencergibb]

yes, but you would also have to define you're own IClientConfig since there is no global one.