spring-cloud-kubernetes: KubernetesServerList is not able to fetch endpoints for all namespaces

Hi,

during our investigations how to handle services deployed in several projects within openshift using Zuul as api gateway we ran into a major problem when trying to fetch pods/endpoints

Scenario:

• a Zuul as api gateway using spring-cloud-starter-kubernetes-netflix running a dedicated project inside openshift
• at least one downstream service which is deployed in an other project

When sticking to the fabric8’s DefaultKubernetesClient implementation there are two steps needed in order to perform service discovery:

1) Perform service discovery based on kubernetes services by invoking client.services() In our scenario we want to tweak this a little to discover kubernetes services with a certain label within all namespaces. For example ‘example.com/stage: testing’

This step works fine by extending the DefaultKubernetesClient:

    @Bean
    public KubernetesClient kubernetesClient() {
        DefaultKubernetesClient client = new DefaultKubernetesClient() {
            @Override
            public MixedOperation<Service, ServiceList, DoneableService, Resource<Service, DoneableService>> services() {
                ServiceOperationsImpl serviceOperations = new ServiceOperationsImpl(httpClient, getConfiguration(), null);
                serviceOperations.withLabels(labels);

                return serviceOperations;
            }

        };

        return client;
    }

2) Fetching endpoints for all discovered kubernetes services Here we’re facing the problem: The KubernetesServerList reads the configured namespace from the configuration file/environment (for ‘any namespace’ this property should be null). However, as you can see in the initWithNiwsConfig() method this property is treaded as a string:

this.namespace = clientConfig.getPropertyAsString(KubernetesConfigKey.Namespace, client.getNamespace());

Now, in the getUpdatedListOfServers() method which is invoked to return the list of available instances, a NULL is expected in case you want to fetch all namespaces:

        Endpoints endpoints = namespace != null
                ? client.endpoints().inNamespace(namespace).withName(serviceId).get()
                : client.endpoints().withName(serviceId).get();

Now, of course, an empty string is not null so the client tries to discover endpoints for namespace: “” and it fails.

Unfortunately, even if you try to execute client.endpoints().withName(serviceId).get() it returns NULL because the kubernetes API returns 404. Maybe the API has changed?

So maybe this call should be change to something like

client.endpoints().inAnyNamespace().withLabel("name", serviceId).list()

NOTE: .withLabel(“name”, ServiceId) is not the correct equivalent to .withName(serviceId) In our case we can use a alternative filter here so it’s not a problem for us. But I can see that a generic solution should be implemented here.