docker-compose.yml

version: '2'
services:

  eventstore1:
    image: eventstore/eventstore
    ports:
    - 12113:2113/tcp
    - 11113:1113/tcp
    environment:
      EVENTSTORE_CLUSTER_DNS: eventstore1
      EVENTSTORE_CLUSTER_GOSSIP_PORT: '2112'
      EVENTSTORE_CLUSTER_SIZE: '3'
      EVENTSTORE_EXT_HTTP_PORT_ADVERTISE_AS: '12113'
      EVENTSTORE_EXT_TCP_PORT_ADVERTISE_AS: '11113'
      EVENTSTORE_EXT_IP: '127.0.0.1'
      EVENTSTORE_EXT_IP_ADVERTISE_AS: '127.0.0.1'
      EVENTSTORE_RUN_PROJECTIONS: 'All'
      EVENTSTORE_START_STANDARD_PROJECTIONS: 'True'
    entrypoint:
    - /bin/bash
    command:
    - -c
    - 'sed -i "/IntIpAdvertiseAs\:/d" /etc/eventstore/eventstore.conf && echo "IntIpAdvertiseAs: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && sed -i "/IntIp\:/d" /etc/eventstore/eventstore.conf && echo "IntIp: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && /entrypoint.sh'

  eventstore2:
    image: eventstore/eventstore
    ports:
    - 22113:2113/tcp
    - 21113:1113/tcp
    environment:
      EVENTSTORE_CLUSTER_DNS: eventstore1
      EVENTSTORE_CLUSTER_GOSSIP_PORT: '2112'
      EVENTSTORE_CLUSTER_SIZE: '3'
      EVENTSTORE_EXT_HTTP_PORT_ADVERTISE_AS: '22113'
      EVENTSTORE_EXT_TCP_PORT_ADVERTISE_AS: '21113'
      EVENTSTORE_EXT_IP: '127.0.0.1'
      EVENTSTORE_EXT_IP_ADVERTISE_AS: '127.0.0.1'
      EVENTSTORE_RUN_PROJECTIONS: 'All'
      EVENTSTORE_START_STANDARD_PROJECTIONS: 'True'
    entrypoint:
    - /bin/bash
    command:
    - -c
    - 'sed -i "/IntIpAdvertiseAs\:/d" /etc/eventstore/eventstore.conf && echo "IntIpAdvertiseAs: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && sed -i "/IntIp\:/d" /etc/eventstore/eventstore.conf && echo "IntIp: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && /entrypoint.sh'

  eventstore3:
    image: eventstore/eventstore
    ports:
    - 32113:2113/tcp
    - 31113:1113/tcp
    environment:
      EVENTSTORE_CLUSTER_DNS: eventstore1
      EVENTSTORE_CLUSTER_GOSSIP_PORT: '2112'
      EVENTSTORE_CLUSTER_SIZE: '3'
      EVENTSTORE_EXT_HTTP_PORT_ADVERTISE_AS: '32113'
      EVENTSTORE_EXT_TCP_PORT_ADVERTISE_AS: '31113'
      EVENTSTORE_EXT_IP: '127.0.0.1'
      EVENTSTORE_EXT_IP_ADVERTISE_AS: '127.0.0.1'
      EVENTSTORE_RUN_PROJECTIONS: 'All'
      EVENTSTORE_START_STANDARD_PROJECTIONS: 'True'
    entrypoint:
    - /bin/bash
    command:
    - -c
    - 'sed -i "/IntIpAdvertiseAs\:/d" /etc/eventstore/eventstore.conf && echo "IntIpAdvertiseAs: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && sed -i "/IntIp\:/d" /etc/eventstore/eventstore.conf && echo "IntIp: $$(hostname -i)" >> /etc/eventstore/eventstore.conf && /entrypoint.sh'

http:--127.0.0.1:12113-gossip?format=json

{
  "members": Array[3][
    {
      "instanceId": "17703a26-4a05-4a55-9ceb-51a1c09e1045",
      "timeStamp": "2018-07-26T23:51:29.247396Z",
      "state": "Slave",
      "isAlive": true,
      "internalTcpIp": "172.18.0.5",
      "internalTcpPort": 1112,
      "internalSecureTcpPort": 0,
      "externalTcpIp": "127.0.0.1",
      "externalTcpPort": 31113,
      "externalSecureTcpPort": 0,
      "internalHttpIp": "172.18.0.5",
      "internalHttpPort": 2112,
      "externalHttpIp": "127.0.0.1",
      "externalHttpPort": 32113,
      "lastCommitPosition": 13193981,
      "writerCheckpoint": 13211895,
      "chaserCheckpoint": 13211895,
      "epochPosition": 642,
      "epochNumber": 1,
      "epochId": "0d753a79-8852-434e-9da0-aac19de67cce",
      "nodePriority": 0
    },
    {
      "instanceId": "cc32a80c-a0a6-400e-8926-6274565a9ed2",
      "timeStamp": "2018-07-26T23:51:29.558431Z",
      "state": "Master",
      "isAlive": true,
      "internalTcpIp": "172.18.0.4",
      "internalTcpPort": 1112,
      "internalSecureTcpPort": 0,
      "externalTcpIp": "127.0.0.1",
      "externalTcpPort": 11113,
      "externalSecureTcpPort": 0,
      "internalHttpIp": "172.18.0.4",
      "internalHttpPort": 2112,
      "externalHttpIp": "127.0.0.1",
      "externalHttpPort": 12113,
      "lastCommitPosition": 13193981,
      "writerCheckpoint": 13211895,
      "chaserCheckpoint": 13211895,
      "epochPosition": 642,
      "epochNumber": 1,
      "epochId": "0d753a79-8852-434e-9da0-aac19de67cce",
      "nodePriority": 0
    },
    {
      "instanceId": "b6626ff3-f5c1-496b-8f8a-6048f6767e8a",
      "timeStamp": "2018-07-26T23:51:28.489078Z",
      "state": "Slave",
      "isAlive": true,
      "internalTcpIp": "172.18.0.3",
      "internalTcpPort": 1112,
      "internalSecureTcpPort": 0,
      "externalTcpIp": "127.0.0.1",
      "externalTcpPort": 21113,
      "externalSecureTcpPort": 0,
      "internalHttpIp": "172.18.0.3",
      "internalHttpPort": 2112,
      "externalHttpIp": "127.0.0.1",
      "externalHttpPort": 22113,
      "lastCommitPosition": 13193981,
      "writerCheckpoint": 13211895,
      "chaserCheckpoint": 13211895,
      "epochPosition": 642,
      "epochNumber": 1,
      "epochId": "0d753a79-8852-434e-9da0-aac19de67cce",
      "nodePriority": 0
    }
  ],
  "serverIp": "172.18.0.4",
  "serverPort": 2112
}

TestConnection.cs

using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Logging;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System;
using System.Net;
using System.Threading.Tasks;
using ESClusterSettings = EventStore.ClientAPI.ClusterSettings;
using ESConnection = EventStore.ClientAPI.EventStoreConnection;
using ESConnectionSettings = EventStore.ClientAPI.ConnectionSettings;
using ESUserCredentials = EventStore.ClientAPI.SystemData.UserCredentials;

namespace Apex.Events.EventStore.Test {

    [TestClass]
    public class EventStoreConnections {

        [TestMethod]
        public async Task ConnectToCluster() {

            var tcs = new TaskCompletionSource<object>();

            var settings = ESConnectionSettings.Create()
                .EnableVerboseLogging()
                .SetDefaultUserCredentials(new ESUserCredentials("admin", "changeit"))
                .Build();

            var clusterSettings = ESClusterSettings.Create()
                .DiscoverClusterViaGossipSeeds()
                .SetGossipSeedEndPoints(new[]{
                    new IPEndPoint(IPAddress.Loopback, 12113),
                })
                .Build();


            var connection = ESConnection.Create(settings, clusterSettings, "test connection");

            connection.Closed += (_, e) => {
                // Happens after ten reconnection attempts.
                tcs.SetException(new Exception("Closed"));
            };

            connection.Connected += (_, e) => {
                // Does not happen
                tcs.SetResult(null);
            };

            connection.Disconnected += (_, e) => {
                // Does not happen
                tcs.SetException(new Exception("Disconnected"));
            };

            connection.ErrorOccurred += (_, e) => {
                // Does not happen
                tcs.SetException(e.Exception);
            };

            connection.Reconnecting += (_, e) => {
                // Happens 10 times
            };

            // This succeeds
            await connection.ConnectAsync();

            // This fails
            await tcs.Task;
        }
    }
}