Docker Demo
This demo gives a brief introduction into Docker. Please see my blog post for details. The demo starts 100 Python web servers as individual containers and then connects to each of them querying the index page. These containers are completely isolated from each other and run, like virtual machines, with their own file systems and IP address.
The demo is controlled by a Makefile. Please have a look at this Makefile to see the different Docker commands used. Also have a look at the Dockerfiles used to build the Docker images in python/Dockerfile and webserver/Dockerfile.
Have fun with lightweight virtual machines made simple with Docker and feel free to contact me.
Prerequisites
Docker builds upon Linux Containers (LXC) and thus, only runs on Linux. In order to allow you to also play with Docker on non-Linux machines, there are two ways to run this demo, i.e., inside a Vagrant Box or directly on Linux. Please see the respective subsections below. For both cases you need to install make.
Vagrant Box
If you decide to run the demo inside a Vagrant box, please install Vagrant accordingly. The supplied Vagrantfile requires Vagrant version 1.4.0 or higher, because starting from that version Docker can be automatically installed. As provider, VirtualBox is assumed. Once Vagrant is installed, just run
vagrant up; vagrant sshcd /vagrant
in the root directory. Then follow the same instructions as for native Linux.
Native Linux
If you decide to run the demo on a native Linux, please install Docker according to your distribution. There are How-Tos for many different distributions in the Docker documentation.
Running the Demo
1. Build Images
In the first step, two Docker images are build. First, starting from an Ubuntu base image, Python is added. From this Python image, a python script comprising a simple web server is added to build the web server images.
make build
2. Starting containers
In the second step, a number of LXC containers is started; by default 100.
make run
You can overwrite the number of server containers to start:
NUM_OF_SERVERS=20 make -e run
3. Running Demo
In order to run the demo, querying the web server containers, run
make demo
For each container you will get an output similar to this example, where three containers are queried from your host.
Hello 172.17.42.1, I am 172.17.0.54. Hello 172.17.42.1, I am 172.17.0.53. Hello 172.17.42.1, I am 172.17.0.52.
After running the demo once, log files from each conainter will be
stored in the directory logs where you can see, that each container
was accessed. The logs are generated from inside the containers, using
their individual IP address as log file name.
You can re-run the demo multiple times.
Show Running Containers
If you want to see the number of running containers, run
docker ps
4. Stopping containers
In order to stop all running containers, run
make stop
and to clean up run
make clean