Test service that uses eureka and ribbon

Question

I'm building an application using microservices with the netflix stack and spring boot. One thing that bugs me is that I have no integration tests yet, where I can mock the surrounding services.

So, I have service A which is a eureka client with ribbon to resolve the eureka name to the URL of a registered service B during a call.

So ideally I want to start the application with the integrationtest annotations of spring boot, use wiremock to simulate the service B and then call the method of service A, this should call my mocked service B using the symbolic name of the service.

Did anyone already solve this? I have searched for blog entries etc. of people doing this already, but couldn't find any...

I know of the SO article Mock an Eureka Feign Client for Unittesting but as far as I can see this just prevents the discovery client from complaining.

Answer 1

The following code (taken from https://github.com/Netflix/eureka/blob/a7a8d278e6399bbff5faa49b9fcbcd7ea9e854f4/eureka-core/src/test/java/com/netflix/eureka/mock/MockRemoteEurekaServer.java) may be helpful to you;

public class MockRemoteEurekaServer extends ExternalResource {

public static final String EUREKA_API_BASE_PATH = "/eureka/v2/";

private final Map<String, Application> applicationMap;
private final Map<String, Application> applicationDeltaMap;
private final Server server;
private boolean sentDelta;
private int port;
private volatile boolean simulateNotReady;

public MockRemoteEurekaServer(int port, Map<String, Application> applicationMap,
                              Map<String, Application> applicationDeltaMap) {
    this.applicationMap = applicationMap;
    this.applicationDeltaMap = applicationDeltaMap;
    ServletHandler handler = new AppsResourceHandler();
    EurekaServerConfig serverConfig = new DefaultEurekaServerConfig();
    EurekaServerContext serverContext = mock(EurekaServerContext.class);
    when(serverContext.getServerConfig()).thenReturn(serverConfig);

    handler.addFilterWithMapping(ServerRequestAuthFilter.class, "/*", 1).setFilter(new ServerRequestAuthFilter(serverContext));
    handler.addFilterWithMapping(RateLimitingFilter.class, "/*", 1).setFilter(new RateLimitingFilter(serverContext));
    server = new Server(port);
    server.addHandler(handler);
    System.out.println(String.format(
            "Created eureka server mock with applications map %s and applications delta map %s",
            stringifyAppMap(applicationMap), stringifyAppMap(applicationDeltaMap)));
}

@Override
protected void before() throws Throwable {
    start();
}

@Override
protected void after() {
    try {
        stop();
    } catch (Exception e) {
        Assert.fail(e.getMessage());
    }
}

public void start() throws Exception {
    server.start();
    port = server.getConnectors()[0].getLocalPort();
}

public void stop() throws Exception {
    server.stop();
}

public boolean isSentDelta() {
    return sentDelta;
}

public int getPort() {
    return port;
}

public void simulateNotReady(boolean simulateNotReady) {
    this.simulateNotReady = simulateNotReady;
}

private static String stringifyAppMap(Map<String, Application> applicationMap) {
    StringBuilder builder = new StringBuilder();
    for (Map.Entry<String, Application> entry : applicationMap.entrySet()) {
        String entryAsString = String.format("{ name : %s , instance count: %d }", entry.getKey(),
                entry.getValue().getInstances().size());
        builder.append(entryAsString);
    }
    return builder.toString();
}

private class AppsResourceHandler extends ServletHandler {

    @Override
    public void handle(String target, HttpServletRequest request, HttpServletResponse response, int dispatch)
            throws IOException, ServletException {

        if (simulateNotReady) {
            response.setStatus(HttpServletResponse.SC_FORBIDDEN);
            return;
        }
        String authName = request.getHeader(AbstractEurekaIdentity.AUTH_NAME_HEADER_KEY);
        String authVersion = request.getHeader(AbstractEurekaIdentity.AUTH_VERSION_HEADER_KEY);
        String authId = request.getHeader(AbstractEurekaIdentity.AUTH_ID_HEADER_KEY);

        Assert.assertNotNull(authName);
        Assert.assertNotNull(authVersion);
        Assert.assertNotNull(authId);

        Assert.assertTrue(!authName.equals(ServerRequestAuthFilter.UNKNOWN));
        Assert.assertTrue(!authVersion.equals(ServerRequestAuthFilter.UNKNOWN));
        Assert.assertTrue(!authId.equals(ServerRequestAuthFilter.UNKNOWN));

        for (FilterHolder filterHolder : this.getFilters()) {
            filterHolder.getFilter().doFilter(request, response, new FilterChain() {
                @Override
                public void doFilter(ServletRequest request, ServletResponse response)
                        throws IOException, ServletException {
                    // do nothing;
                }
            });
        }

        String pathInfo = request.getPathInfo();
        System.out.println(
                "Eureka resource mock, received request on path: " + pathInfo + ". HTTP method: |" + request
                        .getMethod() + '|');
        boolean handled = false;
        if (null != pathInfo && pathInfo.startsWith("")) {
            pathInfo = pathInfo.substring(EUREKA_API_BASE_PATH.length());
            if (pathInfo.startsWith("apps/delta")) {
                Applications apps = new Applications();
                for (Application application : applicationDeltaMap.values()) {
                    apps.addApplication(application);
                }
                apps.setAppsHashCode(apps.getReconcileHashCode());
                sendOkResponseWithContent((Request) request, response, toJson(apps));
                handled = true;
                sentDelta = true;
            } else if (pathInfo.startsWith("apps")) {
                Applications apps = new Applications();
                for (Application application : applicationMap.values()) {
                    apps.addApplication(application);
                }
                apps.setAppsHashCode(apps.getReconcileHashCode());
                sendOkResponseWithContent((Request) request, response, toJson(apps));
                handled = true;
            }
        }

        if (!handled) {
            response.sendError(HttpServletResponse.SC_NOT_FOUND,
                    "Request path: " + pathInfo + " not supported by eureka resource mock.");
        }
    }

    private void sendOkResponseWithContent(Request request, HttpServletResponse response, String content)
            throws IOException {
        response.setContentType("application/json; charset=UTF-8");
        response.setStatus(HttpServletResponse.SC_OK);
        response.getOutputStream().write(content.getBytes("UTF-8"));
        response.getOutputStream().flush();
        request.setHandled(true);
        System.out.println("Eureka resource mock, sent response for request path: " + request.getPathInfo() +
                " with content" + content);
    }
}

private String toJson(Applications apps) throws IOException {
    return new EurekaJsonJacksonCodec().getObjectMapper(Applications.class).writeValueAsString(apps);
}

}

Answer 2

One option would be to use Camel to mock/replace the Eureka endpoints. There should be config telling your app where to look for Eureka, so override that in your test configuration to point to new endpoint.

Then create a Camel route in test/src using either jetty or http to represent this new endpoint, which would return a response that the LoadBalancerClient expects. That response would have the URI under test (i.e. your application).