For users

1.1. Introduction

Containerization is a method to isolate computing environment (operating system, data, software, configurations, etc.) into reusable packages called images. These are binary files which can easily be transferred between different machines. Images are instantiated into running Containers by a Container Engine. From user perspective, working with the Container is similar to working with another operating system on the shared hardware resources. This resembles what Virtual Machines provide. However, there are important technical differences between Container and Virtual Machine technologies. Mainly, any number of Containers can be executed by a single Container Engine on a single operating system. In case of Virtual Machines, each runs its own operating system with its own layer of hardware abstraction. In consequence, Containers are in general quicker to start and easier to operate.

1.2. Docker

The main Containerization technology used now is Docker. It consists of image file format description, the Container Engine and other components. It is available for Linux, macOS and Windows.

For more information, check Get Started

1.3. uDocker

uDocker is "a basic user tool to execute simple docker containers in user space without requiring root privileges".

For more information, check indigo-dc/udocker

1.4. Docker vs uDocker

Important: While uDocker has mostly identical commands and parameters as Docker, there are some minor differences:

Docker:
- docker create: prepare a container from an image
- docker start: start a prepared container
- docker run: prepare a new container and start it in a single step
- docker exec: execute commands on a started container
uDocker:
- udocker create: prepare a container from an image
- udocker run: execute commands on an existing container or prepare a new container and execute command on it
- There is no udocker start and udocker exec!

In consequence, the typical usage for Docker is combination of docker run and optionally docker exec. For uDocker, the typical usage is a combination of udocker create and udocker run.

Please be aware not to mix these usage scenarios.

uDocker is slower to prepare a container, so incorrect usage of udocker run may end up in starting multiple containers and each operation taking a long time.

1.5. Goal

The goal of IMAS Docker creation is to prepare a Docker image containing full IMAS environment with additional tools such as Kepler and FC2K.

1.6. Latest IMAS Docker image

IMAS version: 3.20.0
UAL version: 3.8.3
Kepler present
FC2K not present yet
Available on the Gateway: ~g2tomz/public/imas-installer-20180921112143.tar.xz

1.7. Preparing uDocker on Gateway

mkdir -p ~/.local/bin $ITMWORK/dot-udocker
ln -s $ITMWORK/dot-udocker ~/.udocker
curl https://raw.githubusercontent.com/indigo-dc/udocker/master/udocker.py > ~/.local/bin/udocker
chmod u+rx ~/.local/bin/udocker
echo "tmpdir='$ITMSCRATCH'" > ~/.udocker/udocker.conf
~/.local/bin/udocker install

1.8. Loading Docker image

Docker on your own compujter:

scp login.eufus.eu:~g2tomz/public/imas-installer-20180921112143.tar.xz ./
xzcat imas-installer-20180921112143.tar.xz | docker load

uDocker on Gateway:

xzcat ~g2tomz/public/imas-installer-20180921112143.tar.xz | ~/.local/bin/udocker load

1.9. Demonstration 1: Python script

Create a container and start a shell in it:

Docker on your own computer:

docker run --interactive --tty --name imas imas-installer:20180921112143

uDocker on Gateway:

~/.local/bin/udocker create --name=imas imas-installer:20180921112143
~/.local/bin/udocker run imas

In the container shell, execute:

module load imas
imasdb test
python /home/imas/imas-installer/src/$IMAS_VERSION/ual/$UAL_VERSION/examples/dd-v3/python/put_pf.py

On the host machine, execute:

docker cp imas:/home/imas/public/imasdb/test/3/0/ids_120001.characteristics /tmp/
docker cp imas:/home/imas/public/imasdb/test/3/0/ids_120001.datafile /tmp/
docker cp imas:/home/imas/public/imasdb/test/3/0/ids_120001.tree /tmp/

Transfer the generated IDSes to the Gateway:

scp /tmp/ids_120001.* login.eufus.eu:public/imasdb/test/3/0/

1.10. Demonstration 2: Kepler workflow

Start a new Docker container

docker run --interactive --tty --name imas imas-installer