Overview

Teaching: 5 min
Exercises: 5 min

Questions

• How can we set up an environment to run over Run I simplified files.

Objectives

• Remind ourselves of how to set up Docker to use ROOT.

Setting up your environment

Using a local environment

If you already have an environment set up locally on your computer that has ROOT version 6 or higher, you should be able to run these exercises without any additional changes.

Using Docker

If you do not have a completely local installation of ROOT, you are recommended to use Docker, as per the pre-exercises and previous lessons.

Ideally, you have already downloaded Docker and tested it out when you completed the Docker pre-exercise for this workshop.

The specific episode is Using Docker with CMS Open Data. You will want to scroll down to Download the docker images for ROOT and python tools and start container and then just below that, ROOT container. Please make sure you have gone through that lesson, as we will be following most of the instructions about how to launch the container, with some minimal modifications.

Create a local directory to store your work

Before you start up the Docker container, create a local directory where we will store files. Let’s call it cms_open_data_run1. If you were on Linux or in a Mac terminal, you would type something like

mkdir cms_open_data_run1

Launch Docker

We’ll follow the instructions from the previous lesson on Docker except that

• We will call this new instance of the container my_run1
• We will mount a new volume which is our cms_open_data_run1 directory

If you are on native Linux and want to use X11-forwarding, use

docker run -it --name my_run1 --net=host --env="DISPLAY" -v $HOME/.Xauthority:/home/cmsusr/.Xauthority:rw -v ${HOME}/cms_open_data_run1:/code gitlab-registry.cern.ch/cms-cloud/root-vnc:latest

On MacOS and Windows WSL2 (and on native Linux if you do not want to use X11-forwarding), use

docker run -it --name my_run1 -P -p 5901:5901 -p 6080:6080 -v ${HOME}/cms_open_data_run1:/code gitlab-registry.cern.ch/cms-cloud/root-vnc:latest

This opens a bash shell where you can type your commands. Edit files in the cms_open_data_run1 directory on your local computer, but run the commands in the container.

For graphics, on native Linux, use X11-forwarding. On other systems, use VNC that is installed in the container and start the graphics windows with vnc_start. Open the browser window in the address given at the start message (http://127.0.0.1:6080/vnc.html) with the default VNC password is cms.cern. It shows an empty screen to start with and all graphics will pop up there.

Type exit to leave the container, and if you have started VNC, stop it first:

stop_vnc
exit

Key Points

• Docker can reduce the overhead in setting up a ROOT environment.