To benefit from using a loadbalancer we need several machines to distribute the traffic on, evidently.
Thanks to Docker we simply run
docker run -d -p 81:80 testwebsite:1
to get a second machine. This time the container port of the webserver is mapped to port 81. If you now visit <IP OF YOUR VM>:81 you should see your test website.
You can have as many machines as you want to. Simply pay attention to the ports.
Of course we don’t want to write this command manually each time when we want to create a new container. Especially not when we want about 100 new containers. That’s why we wrote a small bash script, which does the job for us.
This is Part 2 of a series of posts. You can find Part 1 here: https://blog.mi.hdm-stuttgart.de/index.php/2016/01/03/more-docker-more-power-part-1-setting-up-virtualbox/
In the first part of this series we have set up two VirtualBox machines. One functions as the load balancer and the other will house our services. As the next step we want to install docker on the service VM. To do that enter the following commands in the bash:
$ wget -qO- https://get.docker.com/ | sh
$ sudo gpasswd -a <username> docker
$ newgrp docker
This downloads and installs Docker, adds your user to the docker user group and logs you into this new group to allow you to create and run containers.