In most cases, load balancing for traffic inside of a DC/OS™ cluster - referred to internal or East-West load balancing - is managed through the DC/OS layer-4 load-balancer (dcos-l4lb), which is part of the networking layer (dcos-net) of the DC/OS platform. With the DC/OS layer-4 load-balancer, you configure load balancing through virtual IP addresses in app definitions without creating a separate load balancing configuration file.

In some cases, however, you might find it desirable or necessary to use Edge-LB for load balancing the traffic inside of a DC/OS cluster. For example, if you need layer-7 load balancing capability at the application level for traffic within the cluster, you can configure an Edge-LB pool to handle load balancing for internal-only traffic.

This section shows how to set Edge-LB pool configuration options to enable internal load balancing for services running inside of a DC/OS cluster.

Before you begin

Before you create Edge-LB pools and pool configuration files, you should have DC/OS Enterprise cluster nodes installed and ready to use, and have previously downloaded and installed the latest Edge-LB packages.

You must have:

• Edge-LB installed as described in the Edge-LB installation instructions.
• The core DC/OS command-line interface (CLI) installed and configured to communicate with the DC/OS cluster.
• The edgelb command-line interface (CLI) installed.
• An active and properly-configured DC/OS Enterprise cluster, with at least one DC/OS private agent node to run the load-balanced service and at least one DC/OS public agent node for exposing the load-balanced service.

For information about installing Edge-LB packages, see the installation instructions.

Configure internal (East / West) load balancing

If you have client requests originating inside of a cluster for access to applications running on private agent nodes, you may want to configure one or more Edge-LB pools to route those requests for internal load balancing.

To configure Edge-LB for internal load balancing

1. Open a text editor, then copy and paste the following sample settings to create the internal-lb.json pool configuration file:

   {
     "apiVersion": "V2",
     "name": "internal-lb",
     "role": "*",
     "count": 1,
     "haproxy": {
       "stats": {
         "bindPort": 15001
       },
       "frontends": [{
         "bindPort": 15000,
         "protocol": "HTTP",
         "linkBackend": {
           "defaultBackend": "app-backend"
         }
       }],
       "backends": [{
         "name": "app-backend",
         "protocol": "HTTP",
         "services": [{
           "marathon": {
             "serviceID": "/my-app"
           },
           "endpoint": {
             "portName": "web"
           }
         }]
       }]
     }
   }
   

2. Review the sample settings to see how the following field values need to be modified to enable load balancing for internal service requests:

   • Set the pool.haproxy.stats.bindPort and pool.haproxy.frontend.bindPort fields to a port that is available on at least one private agent.

   • Set the pool.role to something other than the default slave_public value. In most cases, you can set this field using the "*" wildcard unless you have created a separate role for this purpose.

3. Deploy the modified Edge-LB pool configuration:

   dcos edgelb create internal-lb.json
   

4. Verify access by navigating to the private agent IP address and port number.