This tutorial demonstrates how to set up three services with a single Edge-LB pool instance. This flexibility allows you to configure Edge-LB pools depending on your needs to achieve high availability in your environment. For example, if you have 90 services running on the DC/OS™ cluster, you can configure 30 Edge-LB pool instances with 3 services each to load balance all 90 services.

Before you begin

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.

Create and deploy sample apps

Copy and paste the following JSON settings to create the sample app definition for the ping service in, and save, the ping.json file:

{
  "id": "/ping",
  "cpus": 0.1,
  "mem": 32,
  "instances": 1,
  "cmd": "echo \"pong\" > index.html && python -m http.server $PORT0",
  "container": {
    "type": "DOCKER",
    "docker": {
      "image": "python:3"
    }
  },
  "healthChecks": [
  {
    "protocol": "MESOS_HTTP",
    "path": "/",
    "portIndex": 0,
    "gracePeriodSeconds": 5,
    "intervalSeconds": 10,
    "timeoutSeconds": 10,
    "maxConsecutiveFailures": 3
  }
  ],
  "portDefinitions": [
  {
    "protocol": "tcp",
    "port": 0,
    "name": "pong-port"
  }
  ],
  "requirePorts": true
}

Deploy the ping.json sample app definition:
```
dcos marathon app add ping.json
```

Copy and paste the following sample app definition to create the nginx.json file for the NGINX™ service:

{
  "id": "/nginx",
  "cpus": 0.1,
  "instances": 1,
  "mem": 128,
  "container": {
    "portMappings": [
      {
        "containerPort": 80,
        "protocol": "tcp",
        "name": "nginx-port"
      }
    ],
    "type": "MESOS",
    "docker": {
      "image": "nginx"
    }
  },
  "networks": [
    {
      "mode": "container/bridge"
    }
]
}

Deploy the nginx.json sample app definition:
```
dcos marathon app add nginx.json
```

Copy and paste the following sample app definition to create the echo.json file:

{
  "id": "/echo",
  "args": [
    "-listen", ":80",
    "-text", "\"Hello from Marathon!\""
  ],
  "cpus": 0.1,
  "instances": 1,
  "mem": 128,
  "container": {
    "portMappings": [
      {
        "containerPort": 80,
        "protocol": "tcp",
        "name": "echo-port"
      }
    ],
    "type": "MESOS",
    "docker": {
      "image": "hashicorp/http-echo"
    }
  },
  "networks": [
    {
      "mode": "container/bridge"
    }
]
}

Deploy the echo.json sample app definition:
```
dcos marathon app add echo.json
```

Create the Edge-LB pool configuration file

Copy and paste the following JSON settings to create the sample pool configuration file for the deployed services in, and save, the multi-lb-pool.json file:

{
  "apiVersion": "V2",
  "name": "multi-lb",
  "count": 1,
  "haproxy": {
    "frontends": [
    {
      "bindPort": 15001,
      "protocol": "HTTP",
      "linkBackend": {
        "defaultBackend": "ping-backend"
      }
    },
    {
      "bindPort": 15002,
      "protocol": "HTTP",
      "linkBackend": {
        "defaultBackend": "nginx-backend"
      }
    },
    {
      "bindPort": 15003,
      "protocol": "HTTP",
      "linkBackend": {
        "defaultBackend": "echo-backend"
      }
    }
  ],
    "backends": [
    {
      "name": "ping-backend",
      "protocol": "HTTP",
      "services": [
      {
        "marathon": {
          "serviceID": "/ping"
        },
        "endpoint": {
          "portName": "pong-port"
        }
      }
    ]
    },
    {
      "name": "nginx-backend",
      "protocol": "HTTP",
      "services": [
        {
        "marathon": {
          "serviceID": "/nginx"
        },
        "endpoint": {
          "portName": "nginx-port"
        }
      }
    ]
    },
    {
      "name": "echo-backend",
      "protocol": "HTTP",
      "services": [
      {
        "marathon": {
          "serviceID": "/echo"
        },
        "endpoint": {
          "portName": "echo-port"
        }
      }
    ]
    }
  ],
    "stats": {
      "bindPort": 0
    }
  }
}

Deploy the Edge-LB pool instance to expose and access all three services using the multi-lb.json pool configuration file:
```
dcos edgelb create multi-lb-pool.json
```

Verify deployment status

Verify that the services and the pool instance have been deployed successfully :
```
dcos marathon app list
```
Verify the pool configuration for frontend and stats ports:
```
dcos edgelb list
```
Verify the pool-related configuration settings:
```
dcos edgelb show multi-lb
```
Verify the Mesos tasks for the services and the Edge-LB pool instances:
```
dcos task list
```
Verify that the Edge-LB pool instance was deployed successfully with the configured frontend and backend ports:
```
dcos edgelb endpoints multi-lb
```

Verify service access using frontend ports

Verify that you can access the following deployed services using the public IP address and the assigned frontend ports:
- ping service:
```
http://<public_agent_public_IP>:15001
```
- nginx service:
```
http://<public_agent_public_IP>:15002
```
- echo service:
```
http://<public_agent_public_IP>:15003
```
When you navigate to the public IP address and specified port, verify that you can see the following pages:
- pong
- Welcome to Nginx
- Hello from Marathon!
If you cannot access one of the pages, check that the Edge-LB frontend ports do not conflict with other ports you are currently using.

Exposing multiple services in a single pool

How to load balance multiple services in a single Edge-LB instance

Before you begin

Create and deploy sample apps

Create the Edge-LB pool configuration file

Verify deployment status

Verify service access using frontend ports