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Support sticky sessions under SWARM Mode.

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SWARM Mode has it's own built in Load balancer, so if we want to leverage sticky sessions,
 or if we would just prefer to bypass it and go directly to the containers (aka tasks), via
	--label traefik.backend.disable.swarm.loadbalancer=true
 then we need to let Traefik know about the underlying tasks and register them as
 services within it's backend.
This commit is contained in:
Mike Foley 2017-01-07 03:20:52 -05:00 • committed by Emile Vauge
parent 106e5c1f92
commit d2b47a5681
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3 changed files with 157 additions and 9 deletions
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88
docs/user-guide/swarm-mode.md
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@ -47,6 +47,7 @@ docker-machine ssh worker1 "docker swarm join \
--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 $(docker-machine ip worker2) \
@ -119,15 +120,22 @@ docker-machine ssh manager "docker service create \
--name whoami0 \
--label traefik.port=80 \
--network traefik-net \
--label traefik.frontend.rule=Host:whoami0.traefik \
--label traefik.backend=whoami0 \
emilevauge/whoami"
docker-machine ssh manager "docker service create \
--name whoami1 \
--label traefik.port=80 \
--network traefik-net \
--label traefik.frontend.rule=Host:whoam1.traefik \
--label traefik.backend=whoami1 \
--label traefik.backend.loadbalancer.sticky=true \
emilevauge/whoami"
```
NOTE: If using `docker stack deploy`, there is [a specific way that the labels must be defined in the docker-compose file](https://github.com/containous/traefik/issues/994#issuecomment-269095109).
Note that we set whoami1 to use sticky sessions (`--label traefik.backend.loadbalancer.sticky=true`). We'll demonstrate that later.
If using `docker stack deploy`, there is [a specific way that the labels must be defined in the docker-compose file](https://github.com/containous/traefik/issues/994#issuecomment-269095109).
Check that everything is scheduled and started:
@ -220,6 +228,84 @@ X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c
```
## Scale both services
```sh
docker-machine ssh manager "docker service scale whoami0=5"
docker-machine ssh manager "docker service scale whoami1=5"
```
Check that we now have 5 replicas of each `whoami` service:
```sh
docker-machine ssh manager "docker service ls"
ID NAME REPLICAS IMAGE COMMAND
ab046gpaqtln whoami0 5/5 emilevauge/whoami
cgfg5ifzrpgm whoami1 5/5 emilevauge/whoami
dtpl249tfghc traefik 1/1 traefik --docker --docker.swarmmode --docker.domain=traefik --docker.watch --web
```
## Access to your whoami0 through Træfɪk multiple times.
Repeat the following command multiple times and note that the Hostname changes each time as Traefik load balances each request against the 5 tasks.
```sh
curl -H Host:whoami0.traefik http://$(docker-machine ip manager)
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
```
Do the same against whoami1.
```sh
curl -H Host:whoami1.traefik http://$(docker-machine ip manager)
Hostname: ba2c21488299
IP: 127.0.0.1
IP: ::1
IP: 10.0.9.4
IP: fe80::42:aff:fe00:904
IP: 172.18.0.2
IP: fe80::42:acff:fe12:2
GET / HTTP/1.1
Host: 10.0.9.4:80
User-Agent: curl/7.35.0
Accept: */*
Accept-Encoding: gzip
X-Forwarded-For: 192.168.99.1
X-Forwarded-Host: 10.0.9.4:80
X-Forwarded-Proto: http
X-Forwarded-Server: 8fbc39271b4c
```
Wait, I thought we added the sticky flag to whoami1? Traefik relies on a cookie to maintain stickyness so you'll need to test this with a browser.
First you need to add whoami1.traefik to your hosts file:
```ssh
if [ -n "$(grep whoami1.traefik /etc/hosts)" ];
then
echo "whoami1.traefik already exists (make sure the ip is current)";
else
sudo -- sh -c -e "echo '$(docker-machine ip manager)\twhoami1.traefik'
>> /etc/hosts";
fi
```
Now open your browser and go to http://whoami1.traefik/
You will now see that stickyness is maintained.
![](http://i.giphy.com/ujUdrdpX7Ok5W.gif)