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