307 lines
8.6 KiB
Markdown
307 lines
8.6 KiB
Markdown
# Docker Swarm (mode) cluster
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This section explains how to create a multi-host docker cluster with
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swarm mode using [docker-machine](https://docs.docker.com/machine) and
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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
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(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. It's a shorter version of
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the [swarm tutorial](https://docs.docker.com/engine/swarm/swarm-tutorial/).
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```sh
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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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2. get the token for other host to join
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3. on both workers, join the cluster with the token
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```sh
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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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```sh
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docker-machine ssh manager docker node ls
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ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS
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2a770ov9vixeadep674265u1n worker1 Ready Active
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dbi3or4q8ii8elbws70g4hkdh * manager Ready Active Leader
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esbhhy6vnqv90xomjaomdgy46 worker2 Ready Active
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```
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Finally, let's create a network for Træfik to use.
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```sh
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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. The only
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requirement for Træfik to work with swarm mode is that it needs to run
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on a manager node — we are going to use a
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[constraint](https://docs.docker.com/engine/reference/commandline/service_create/#/specify-service-constraints-constraint) for
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that.
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```
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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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--web"
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```
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Let's explain this command:
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- `--publish 80:80 --publish 8080:8080`: we publish port `80` and
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`8080` on the cluster.
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- `--constraint=node.role==manager`: we ask docker to schedule Træfik
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on a manager node.
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- `--mount type=bind,source=/var/run/docker.sock,target=/var/run/docker.sock`:
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we bind mount the docker socket where Træfik is scheduled to be able
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to speak to the daemon.
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- `--network traefik-net`: we attach the Træfik service (and thus
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the underlying container) to the `traefik-net` network.
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- `--docker`: enable docker backend, and `--docker.swarmmode` to
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enable the swarm mode on Træfik.
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- `--web`: 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,
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here [whoami](https://github.com/emilevauge/whoami), a simple web
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server in Go. We start 2 services, on the `traefik-net` network.
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```sh
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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 that we set whoami1 to use sticky sessions (`--label traefik.backend.loadbalancer.sticky=true`). We'll demonstrate that later.
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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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```sh
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docker-machine ssh manager "docker service ls"
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ID NAME REPLICAS IMAGE COMMAND
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ab046gpaqtln whoami0 1/1 emilevauge/whoami
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cgfg5ifzrpgm whoami1 1/1 emilevauge/whoami
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dtpl249tfghc traefik 1/1 traefik --docker --docker.swarmmode --docker.domain=traefik --docker.watch --web
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```
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## Access to your apps through Træfik
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```sh
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curl -H Host:whoami0.traefik http://$(docker-machine ip manager)
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Hostname: 8147a7746e7a
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.3
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IP: fe80::42:aff:fe00:903
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IP: 172.18.0.3
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IP: fe80::42:acff:fe12:3
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GET / HTTP/1.1
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Host: 10.0.9.3:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.3:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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curl -H Host:whoami1.traefik http://$(docker-machine ip manager)
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Hostname: ba2c21488299
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.4
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IP: fe80::42:aff:fe00:904
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IP: 172.18.0.2
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IP: fe80::42:acff:fe12:2
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GET / HTTP/1.1
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Host: 10.0.9.4:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.4:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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```
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Note that as Træfik is published, you can access it from any machine
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and not only the manager.
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```sh
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curl -H Host:whoami0.traefik http://$(docker-machine ip worker1)
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Hostname: 8147a7746e7a
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.3
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IP: fe80::42:aff:fe00:903
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IP: 172.18.0.3
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IP: fe80::42:acff:fe12:3
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GET / HTTP/1.1
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Host: 10.0.9.3:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.3:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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curl -H Host:whoami1.traefik http://$(docker-machine ip worker2)
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Hostname: ba2c21488299
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.4
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IP: fe80::42:aff:fe00:904
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IP: 172.18.0.2
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IP: fe80::42:acff:fe12:2
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GET / HTTP/1.1
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Host: 10.0.9.4:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.4:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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```
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## Scale both services
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```sh
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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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```sh
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docker-machine ssh manager "docker service ls"
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ID NAME REPLICAS IMAGE COMMAND
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ab046gpaqtln whoami0 5/5 emilevauge/whoami
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cgfg5ifzrpgm whoami1 5/5 emilevauge/whoami
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dtpl249tfghc traefik 1/1 traefik --docker --docker.swarmmode --docker.domain=traefik --docker.watch --web
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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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```sh
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curl -H Host:whoami0.traefik http://$(docker-machine ip manager)
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Hostname: 8147a7746e7a
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.3
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IP: fe80::42:aff:fe00:903
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IP: 172.18.0.3
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IP: fe80::42:acff:fe12:3
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GET / HTTP/1.1
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Host: 10.0.9.3:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.3:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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```
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Do the same against whoami1.
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```sh
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curl -H Host:whoami1.traefik http://$(docker-machine ip manager)
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Hostname: ba2c21488299
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IP: 127.0.0.1
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IP: ::1
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IP: 10.0.9.4
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IP: fe80::42:aff:fe00:904
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IP: 172.18.0.2
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IP: fe80::42:acff:fe12:2
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GET / HTTP/1.1
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Host: 10.0.9.4:80
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User-Agent: curl/7.35.0
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Accept: */*
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Accept-Encoding: gzip
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X-Forwarded-For: 192.168.99.1
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X-Forwarded-Host: 10.0.9.4:80
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X-Forwarded-Proto: http
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X-Forwarded-Server: 8fbc39271b4c
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```
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Wait, I thought we added the sticky flag to whoami1? Traefik relies on a cookie to maintain stickyness so you'll need to test this with a browser.
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First you need to add whoami1.traefik to your hosts file:
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```ssh
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if [ -n "$(grep whoami1.traefik /etc/hosts)" ];
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then
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echo "whoami1.traefik already exists (make sure the ip is current)";
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else
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sudo -- sh -c -e "echo '$(docker-machine ip manager)\twhoami1.traefik'
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>> /etc/hosts";
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fi
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```
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Now open your browser and go to http://whoami1.traefik/
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You will now see that stickyness is maintained.
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