# Swarm cluster

This section explains how to create a multi-host [swarm](https://docs.docker.com/swarm) cluster using [docker-machine](https://docs.docker.com/machine/) and how to deploy Traefik on it.

The cluster consists of:

- 2 servers
- 1 swarm master
- 2 swarm nodes
- 1 [overlay](https://docs.docker.com/network/overlay/) network (multi-host networking)

## Prerequisites

1. You need to install [docker-machine](https://docs.docker.com/machine/)
2. You need the latest [VirtualBox](https://www.virtualbox.org/wiki/Downloads)

## Cluster provisioning

We first follow [this guide](https://docs.docker.com/engine/userguide/networking/get-started-overlay/) to create the cluster.

### Create machine `mh-keystore`

This machine is the service registry of our cluster.

```shell
docker-machine create -d virtualbox mh-keystore
```

Then we install the service registry [Consul](https://consul.io) on this machine:

```shell
eval "$(docker-machine env mh-keystore)"
docker run -d \
    -p "8500:8500" \
    -h "consul" \
    progrium/consul -server -bootstrap
```

### Create machine `mhs-demo0`

This machine is a swarm master and a swarm agent on it.

```shell
docker-machine create -d virtualbox \
    --swarm --swarm-master \
    --swarm-discovery="consul://$(docker-machine ip mh-keystore):8500" \
    --engine-opt="cluster-store=consul://$(docker-machine ip mh-keystore):8500" \
    --engine-opt="cluster-advertise=eth1:2376" \
    mhs-demo0
```

### Create machine `mhs-demo1`

This machine have a swarm agent on it.

```shell
docker-machine create -d virtualbox \
    --swarm \
    --swarm-discovery="consul://$(docker-machine ip mh-keystore):8500" \
    --engine-opt="cluster-store=consul://$(docker-machine ip mh-keystore):8500" \
    --engine-opt="cluster-advertise=eth1:2376" \
    mhs-demo1
```

### Create the overlay Network

Create the overlay network on the swarm master:

```shell
eval $(docker-machine env --swarm mhs-demo0)
docker network create --driver overlay --subnet=10.0.9.0/24 my-net
```

## Deploy Traefik

Deploy Traefik:

```shell
docker $(docker-machine config mhs-demo0) run \
    -d \
    -p 80:80 -p 8080:8080 \
    --net=my-net \
    -v /var/lib/boot2docker/:/ssl \
    traefik \
    -l DEBUG \
    -c /dev/null \
    --docker \
    --docker.domain=traefik \
    --docker.endpoint=tcp://$(docker-machine ip mhs-demo0):2376 \
    --docker.tls \
    --docker.tls.ca=/ssl/ca.pem \
    --docker.tls.cert=/ssl/server.pem \
    --docker.tls.key=/ssl/server-key.pem \
    --docker.tls.insecureSkipVerify \
    --docker.watch \
    --api
```

Let's explain this command:

| Option                                    | Description                                                   |
|-------------------------------------------|---------------------------------------------------------------|
| `-p 80:80 -p 8080:8080`                   | we bind ports 80 and 8080                                     |
| `--net=my-net`                            | run the container on the network my-net                       |
| `-v /var/lib/boot2docker/:/ssl`           | mount the ssl keys generated by docker-machine                |
| `-c /dev/null`                            | empty config file                                             |
| `--docker`                                | enable docker provider                                         |
| `--docker.endpoint=tcp://172.18.0.1:2376` | connect to the swarm master using the docker_gwbridge network |
| `--docker.tls`                            | enable TLS using the docker-machine keys                      |
| `--api`                                   | activate the webUI on port 8080                               |


## Deploy your apps

We can now deploy our app on the cluster, here [whoami](https://github.com/containous/whoami), a simple web server in GO, on the network `my-net`:

```shell
eval $(docker-machine env --swarm mhs-demo0)
docker run -d --name=whoami0 --net=my-net --env="constraint:node==mhs-demo0" containous/whoami
docker run -d --name=whoami1 --net=my-net --env="constraint:node==mhs-demo1" containous/whoami
```

Check that everything is started:

```shell
docker ps
```
```
CONTAINER ID        IMAGE               COMMAND                  CREATED             STATUS              PORTS                                                      NAMES
ba2c21488299        containous/whoami   "/whoamI"                8 seconds ago       Up 9 seconds        80/tcp                                                     mhs-demo1/whoami1
8147a7746e7a        containous/whoami   "/whoamI"                19 seconds ago      Up 20 seconds       80/tcp                                                     mhs-demo0/whoami0
8fbc39271b4c        traefik             "/traefik -l DEBUG -c"   36 seconds ago      Up 37 seconds       192.168.99.101:80->80/tcp, 192.168.99.101:8080->8080/tcp   mhs-demo0/serene_bhabha
```

## Access to your apps through Traefik

```shell
curl -H Host:whoami0.traefik http://$(docker-machine ip mhs-demo0)
```
```yaml
Hostname: 8147a7746e7a
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.3
IP: fe80::42:aff:fe00:903
IP: 172.18.0.3
IP: fe80::42:acff:fe12:3
GET / HTTP/1.1
Host: 10.0.9.3:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.3:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c
```

```shell
curl -H Host:whoami1.traefik http://$(docker-machine ip mhs-demo0)
```
```yaml
Hostname: ba2c21488299
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.4
IP: fe80::42:aff:fe00:904
IP: 172.18.0.2
IP: fe80::42:acff:fe12:2
GET / HTTP/1.1
Host: 10.0.9.4:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.4:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c
```

![GIF Magica](https://i.giphy.com/ujUdrdpX7Ok5W.gif)