# Docker Swarm (mode) cluster This section explains how to create a multi-host docker cluster with swarm mode using [docker-machine](https://docs.docker.com/machine) and how to deploy Træfik on it. The cluster consists of: - 3 servers - 1 manager - 2 workers - 1 [overlay](https://docs.docker.com/engine/userguide/networking/dockernetworks/#an-overlay-network) network (multi-host networking) ## Prerequisites 1. You will need to install [docker-machine](https://docs.docker.com/machine/) 2. You will need the latest [VirtualBox](https://www.virtualbox.org/wiki/Downloads) ## Cluster provisioning First, let's create all the required nodes. It's a shorter version of the [swarm tutorial](https://docs.docker.com/engine/swarm/swarm-tutorial/). ```shell docker-machine create -d virtualbox manager docker-machine create -d virtualbox worker1 docker-machine create -d virtualbox worker2 ``` Then, let's setup the cluster, in order: 1. initialize the cluster 1. get the token for other host to join 1. on both workers, join the cluster with the token ```shell docker-machine ssh manager "docker swarm init \ --listen-addr $(docker-machine ip manager) \ --advertise-addr $(docker-machine ip manager)" export worker_token=$(docker-machine ssh manager "docker swarm \ join-token worker -q") docker-machine ssh worker1 "docker swarm join \ --token=${worker_token} \ --listen-addr $(docker-machine ip worker1) \ --advertise-addr $(docker-machine ip worker1) \ $(docker-machine ip manager)" docker-machine ssh worker2 "docker swarm join \ --token=${worker_token} \ --listen-addr $(docker-machine ip worker2) \ --advertise-addr $(docker-machine ip worker2) \ $(docker-machine ip manager)" ``` Let's validate the cluster is up and running. ```shell docker-machine ssh manager docker node ls ``` ``` ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS 013v16l1sbuwjqcn7ucbu4jwt worker1 Ready Active 8buzkquycd17jqjber0mo2gn8 worker2 Ready Active fnpj8ozfc85zvahx2r540xfcf * manager Ready Active Leader ``` Finally, let's create a network for Træfik to use. ```shell docker-machine ssh manager "docker network create --driver=overlay traefik-net" ``` ## Deploy Træfik Let's deploy Træfik as a docker service in our cluster. The only requirement for Træfik to work with swarm mode is that it needs to run on a manager node - we are going to use a [constraint](https://docs.docker.com/engine/reference/commandline/service_create/#/specify-service-constraints-constraint) for that. ```shell docker-machine ssh manager "docker service create \ --name traefik \ --constraint=node.role==manager \ --publish 80:80 --publish 8080:8080 \ --mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock \ --network traefik-net \ traefik \ --docker \ --docker.swarmmode \ --docker.domain=traefik \ --docker.watch \ --web" ``` Let's explain this command: | Option | Description | |-----------------------------------------------------------------------------|------------------------------------------------------------------------------------------------| | `--publish 80:80 --publish 8080:8080` | we publish port `80` and `8080` on the cluster. | | `--constraint=node.role==manager` | we ask docker to schedule Træfik on a manager node. | | `--mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock` | we bind mount the docker socket where Træfik is scheduled to be able to speak to the daemon. | | `--network traefik-net` | we attach the Træfik service (and thus the underlying container) to the `traefik-net` network. | | `--docker` | enable docker backend, and `--docker.swarmmode` to enable the swarm mode on Træfik. | | `--web` | activate the webUI on port 8080 | ## Deploy your apps We can now deploy our app on the cluster, here [whoami](https://github.com/emilevauge/whoami), a simple web server in Go. We start 2 services, on the `traefik-net` network. ```shell docker-machine ssh manager "docker service create \ --name whoami0 \ --label traefik.port=80 \ --network traefik-net \ emilevauge/whoami" docker-machine ssh manager "docker service create \ --name whoami1 \ --label traefik.port=80 \ --network traefik-net \ --label traefik.backend.loadbalancer.sticky=true \ emilevauge/whoami" ``` !!! note We set `whoami1` to use sticky sessions (`--label traefik.backend.loadbalancer.sticky=true`). We'll demonstrate that later. !!! note If using `docker stack deploy`, there is [a specific way that the labels must be defined in the docker-compose file](https://github.com/containous/traefik/issues/994#issuecomment-269095109). Check that everything is scheduled and started: ```shell docker-machine ssh manager "docker service ls" ``` ``` ID NAME MODE REPLICAS IMAGE PORTS moq3dq4xqv6t traefik replicated 1/1 traefik:latest *:80->80/tcp,*:8080->8080/tcp ysil6oto1wim whoami0 replicated 1/1 emilevauge/whoami:latest z9re2mnl34k4 whoami1 replicated 1/1 emilevauge/whoami:latest ``` ## Access to your apps through Træfik ```shell curl -H Host:whoami0.traefik http://$(docker-machine ip manager) ``` ```yaml Hostname: 5b0b3d148359 IP: 127.0.0.1 IP: 10.0.0.8 IP: 10.0.0.4 IP: 172.18.0.5 GET / HTTP/1.1 Host: whoami0.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.2 X-Forwarded-Host: whoami0.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` ```shell curl -H Host:whoami1.traefik http://$(docker-machine ip manager) ``` ```yaml Hostname: 3633163970f6 IP: 127.0.0.1 IP: 10.0.0.14 IP: 10.0.0.6 IP: 172.18.0.5 GET / HTTP/1.1 Host: whoami1.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.2 X-Forwarded-Host: whoami1.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` !!! note As Træfik is published, you can access it from any machine and not only the manager. ```shell curl -H Host:whoami0.traefik http://$(docker-machine ip worker1) ``` ```yaml Hostname: 5b0b3d148359 IP: 127.0.0.1 IP: 10.0.0.8 IP: 10.0.0.4 IP: 172.18.0.5 GET / HTTP/1.1 Host: whoami0.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.3 X-Forwarded-Host: whoami0.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` ```shell curl -H Host:whoami1.traefik http://$(docker-machine ip worker2) ``` ```yaml Hostname: 3633163970f6 IP: 127.0.0.1 IP: 10.0.0.14 IP: 10.0.0.6 IP: 172.18.0.5 GET / HTTP/1.1 Host: whoami1.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.4 X-Forwarded-Host: whoami1.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` ## Scale both services ```shell docker-machine ssh manager "docker service scale whoami0=5" docker-machine ssh manager "docker service scale whoami1=5" ``` Check that we now have 5 replicas of each `whoami` service: ```shell docker-machine ssh manager "docker service ls" ``` ``` ID NAME MODE REPLICAS IMAGE PORTS moq3dq4xqv6t traefik replicated 1/1 traefik:latest *:80->80/tcp,*:8080->8080/tcp ysil6oto1wim whoami0 replicated 5/5 emilevauge/whoami:latest z9re2mnl34k4 whoami1 replicated 5/5 emilevauge/whoami:latest ``` ## Access to your `whoami0` through Træfik multiple times. Repeat the following command multiple times and note that the Hostname changes each time as Traefik load balances each request against the 5 tasks: ```shell curl -H Host:whoami0.traefik http://$(docker-machine ip manager) ``` ```yaml Hostname: f3138d15b567 IP: 127.0.0.1 IP: 10.0.0.5 IP: 10.0.0.4 IP: 172.18.0.3 GET / HTTP/1.1 Host: whoami0.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.2 X-Forwarded-Host: whoami0.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` Do the same against `whoami1`: ```shell curl -c cookies.txt -H Host:whoami1.traefik http://$(docker-machine ip manager) ``` ```yaml Hostname: 348e2f7bf432 IP: 127.0.0.1 IP: 10.0.0.15 IP: 10.0.0.6 IP: 172.18.0.6 GET / HTTP/1.1 Host: whoami1.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip X-Forwarded-For: 10.255.0.2 X-Forwarded-Host: whoami1.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` Because the sticky sessions require cookies to work, we used the `-c cookies.txt` option to store the cookie into a file. The cookie contains the IP of the container to which the session sticks: ```shell cat ./cookies.txt ``` ``` # Netscape HTTP Cookie File # https://curl.haxx.se/docs/http-cookies.html # This file was generated by libcurl! Edit at your own risk. whoami1.traefik FALSE / FALSE 0 _TRAEFIK_BACKEND http://10.0.0.15:80 ``` If you load the cookies file (`-b cookies.txt`) for the next request, you will see that stickyness is maintained: ```shell curl -b cookies.txt -H Host:whoami1.traefik http://$(docker-machine ip manager) ``` ```yaml Hostname: 348e2f7bf432 IP: 127.0.0.1 IP: 10.0.0.15 IP: 10.0.0.6 IP: 172.18.0.6 GET / HTTP/1.1 Host: whoami1.traefik User-Agent: curl/7.55.1 Accept: */* Accept-Encoding: gzip Cookie: _TRAEFIK_BACKEND=http://10.0.0.15:80 X-Forwarded-For: 10.255.0.2 X-Forwarded-Host: whoami1.traefik X-Forwarded-Proto: http X-Forwarded-Server: 77fc29c69fe4 ``` ![](https://i.giphy.com/ujUdrdpX7Ok5W.gif)