IPVS can direct requests for TCP- and UDP-based services to the real servers, and make services of the real servers appear as virtual services on a single IP address. IPVS is built on top of the Netfilter.[
=SWARM=
==Introduction==
A swarm is a group of machines that are running Docker and joined into a cluster. After that has happened, you continue to run the Docker commands you’re used to, but now they are executed on a cluster by a swarm manager. The machines in a swarm can be physical or virtual. After joining a swarm, they are referred to as nodes.
Source: https://docs.docker.com/get-started/part4/#introduction
<pre>
docker@manager:~$ docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
uzhpeg3ug0ip6f9o3l51c749y * manager Ready Active Leader 18.05.0-ce
kstfblenhtb0dbpzkxo2olssn worker1 Ready Active 18.05.0-ce
pf8jdfmlegbx7dogi6jnbxu2y worker2 Ready Active 18.05.0-ce
</pre>
https://docs.docker.com/engine/swarm/swarm-tutorial/deploy-service/
==Create swarm==
<pre>
docker@manager:~$ docker swarm init --advertise-addr 192.168.42.118
Swarm initialized: current node (uzhpeg3ug0ip6f9o3l51c749y) is now a manager.
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-21qaw0xpv9tj2kjxbmj6jn2jqpbcjjkyeze2nno9yy0wvt0vp9-9k2yyit1x8a11ca50ejxalzhz 192.168.42.118:2377
To add a manager to this swarm, run 'docker swarm join-token manager' and follow the instructions.
</pre>
------------
<pre>
docker@master:~$ docker swarm join-token worker
To add a worker to this swarm, run the following command:
docker swarm join --token SWMTKN-1-25li3z5dk9qianluoo2kk35geu2rwegg6ku6kfpefnyuhq00l5-6lj0p6lhrn0ytr28xohyy74zd 192.168.123.166:2377
</pre>
<pre>
# docker-machine create -d kvm --kvm-network "docker-network" --kvm-disk-size "5000" node1
Running pre-create checks...
Creating machine...
...
To see how to connect your Docker Client to the Docker Engine running on this virtual machine, run: docker-machine env node1
</pre>
<pre>
# docker-machine ssh node1
## .
## ## ## ==
## ## ## ## ## ===
/"""""""""""""""""\___/ ===
~~~ {~~ ~~~~ ~~~ ~~~~ ~~~ ~ / ===- ~~~
\______ o __/
\ \ __/
\____\_______/
_ _ ____ _ _
| |__ ___ ___ | |_|___ \ __| | ___ ___| | _____ _ __
| '_ \ / _ \ / _ \| __| __) / _` |/ _ \ / __| |/ / _ \ '__|
| |_) | (_) | (_) | |_ / __/ (_| | (_) | (__| < __/ |
|_.__/ \___/ \___/ \__|_____\__,_|\___/ \___|_|\_\___|_|
Boot2Docker version 18.05.0-ce, build HEAD : b5d6989 - Thu May 10 16:35:28 UTC 2018
Docker version 18.05.0-ce, build f150324
docker@node1:~$
</pre>
<pre>
docker@node1:~$ docker swarm join --token SWMTKN-1-25li3z5dk9qianluoo2kk35geu2rwegg6ku6kfpefnyuhq00l5-6lj0p6lhrn0ytr28xohyy74zd 192.168.123.166:2377
This node joined a swarm as a worker.
docker@node1:~$ exit
</pre>
<pre>
[root@adamDell2 ~]# docker-machine ssh master docker node ls
ID HOSTNAME STATUS AVAILABILITY MANAGER STATUS ENGINE VERSION
lstjx5br3i0nry3xijgeoc0u8 * master Ready Active Leader 18.05.0-ce
77yip8j71murtcu9kqki2m2in node1 Ready Active 18.05.0-ce
</pre>
Létrehozunk egy szolgáltatást az nginx image-ből. Három példányban fog futni.
<pre>
# docker-machine ssh master docker service create --name nginx --replicas 3 nginx
o7dgqt3yynw3rs7yh2snmyybi
overall progress: 0 out of 3 tasks
1/3:
2/3:
3/3:
</pre>
Nézzük meg, hogy hol jöttek létre a konténerek az új szolgáltatásunkhoz. 2 a masteren, 1 pedig a node1-en fut.
<pre>
# docker-machine ssh master docker service ps nginx
ID NAME IMAGE NODE DESIRED STATE CURRENT STATE ERROR PORTS
5pfmf0noxxfp nginx.1 nginx:latest node1 Running Running about a minute ago
k4osxnv0a8lm nginx.2 nginx:latest master Running Running about a minute ago
t28ndarnryl5 nginx.3 nginx:latest master Running Running about a minute ago
</pre>
Ha csak a '''docker ps''' parancsot futtatjuk le, akkor láthatjuk, hogy csak azt a két konténert látjuk,amit a swarm a master node-on helyezett el.
<pre>
# docker-machine ssh master docker ps -a
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
0386b9b36ad1 nginx:latest "nginx -g 'daemon of…" 3 minutes ago Up 3 minutes 80/tcp nginx.3.t28ndarnryl5r6plfbgcwb9sw
568088b05844 nginx:latest "nginx -g 'daemon of…" 3 minutes ago Up 3 minutes 80/tcp nginx.2.k4osxnv0a8lm0qvwma0qvfat3
</pre>
<br>
<br>
=Create swarm cluster=
A swarm mode cluster-t egy bash szkripttel fogjuk létrehozni. 3 manager-t és 3 worker node-t. Elsőként a három manager virtuális gépet hozzuk létre. Ezután a mg0-ás gépen inicializáljuk a cluster-t, majd az m1 és m2 node-okat manager-ként beléptetjük a cluster-be. Ha ez megvan, akkor létrehozzuk a három worker node-t és azokat worker-ként léptetjük be a cluster-be.
