title: Ribbon without Eureka : Ribbon doesn't remember that a server is down via PingURL
body: <p>I am using Ribbon without Eureka.I am using a ConfigurationBasedServerList to provide the list of server instances like so..</p>
  
  <pre><code>customerinfo.ribbon.listOfServers=localhost:9003,localhost:9008
  </code></pre>
  
  <p>I have configured PingURL with the /health endpoint. I have also configured AvailabilityFilteringRule which needs to filter the sever instances that are not available. like so..</p>
  
  <pre><code>public class RibbonConfig {
  
  @Autowired
  IClientConfig ribbonClientConfig;
  
  @Bean
  public IPing ribbonPing(IClientConfig config) {
      return new PingUrl(true, "/health");
  }
  
  @Bean
  public IRule ribbonRule(IClientConfig config) {
      return new AvailabilityFilteringRule();
  }
  
  }
  </code></pre>
  
  <p>This mostly works well. It doesn't work well in one case. Thats the case when the server instance running on port 9008 is down.</p>
  
  <p>Let me explain with some DEBUG messages.</p>
  
  <pre><code>DEBUG com.netflix.loadbalancer.DynamicServerListLoadBalancer - List of Servers for customerinfo obtained from Discovery client: [localhost:9003, localhost:9008]
  DEBUG com.netflix.loadbalancer.DynamicServerListLoadBalancer - Filtered List of Servers for customerinfo obtained from Discovery client: [localhost:9003, localhost:9008]
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  clearing server list (SET op)
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  addServer [localhost:9003]
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  addServer [localhost:9008]
  com.netflix.loadbalancer.DynamicServerListLoadBalancer - Setting server list for zones: {unknown=[localhost:9003, localhost:9008]}
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  clearing server list (SET op)
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  addServer [localhost:9003]
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  addServer [localhost:9008]
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  forceQuickPing invoked
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  PingTask executing [2] servers configured
  DEBUG com.netflix.loadbalancer.BaseLoadBalancer - LoadBalancer:  Server [localhost:9008] status changed to DEAD
  </code></pre>
  
  <p>Looking at the DEBUG messages. The process thats being followed looks like this:
  1) Clear the server list and add the servers from the config again.
  2) Ping them for their status.
  3) Update the available server list depending on the ping results.</p>
  
  <p>Every 30 secs the above process seems to be happening which is to maintain the DynamicServerList.</p>
  
  <p>Now, the problem is - from the first log statement to the penultimate log statement, ribbon thinks both the server instances are available. So, if there is load balancing request that comes within that time, then there is a chance that its send to the server localhost:9008 which is DOWN.</p>
  
  <p>From my understanding Ribbon library does not keep PingStatistics. I think the library depends on Service Discovery tools like Eureka to provide the DynamicServerlist which are healthy depending on some health checks. </p>
  
  <p>Now, to fix this problem, I can start using Eureka and this problem might vanish. I don't want to use Eureka as my environment doesnt grow/shrink often...its pretty much static.</p>
  
  <p>Is there a config that i am missing here? How do we solve this issue? </p>
  
  <p>I am using "spring-cloud-starter-ribbon" Version 1.2.6.RELEASE.</p>