EVCACHE-454: Ideally, app should not serve traffic until it is health…

…y but this option - ignoreAppEurekaStatus will allow app to ignore application eureka status while trying to initialize evcache client. This feature `may` be required for applications which are behind load balancers. They may fail to register successfully with eureka but are still expected to serve traffic.

evcache-client/src/main/java/com/netflix/evcache/pool/eureka/EurekaNodeListProvider.java

@@ -56,7 +56,14 @@ public EurekaNodeListProvider(ApplicationInfoManager applicationInfoManager, Eur
      */
     @Override
     public Map<ServerGroup, EVCacheServerGroupConfig> discoverInstances(String _appName) throws IOException {
-        if ((applicationInfoManager.getInfo().getStatus() == InstanceStatus.DOWN)) {
+        final Property<Boolean> ignoreAppEurekaStatus = props.get("evcache.ignoreAppEurekaStatus", Boolean.class).orElse(false);
+
+        if (ignoreAppEurekaStatus.get())
+            log.info("Not going to consider the eureka status of the application, to initialize evcache client.");
+
+        if (!ignoreAppEurekaStatus.get() && (applicationInfoManager.getInfo().getStatus() == InstanceStatus.DOWN)) {
+            log.info("Not initializing evcache client as application eureka status is DOWN. " +
+                    "One can override this behavior by setting evcache.ignoreAppEurekaStatus property to true, scoped to your application.");
             return Collections.<ServerGroup, EVCacheServerGroupConfig> emptyMap();
         }