README

This project is used to create a Docker container which can access the CMS LHC experiment's CVMFS file system.

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Setting up the container

Change the password used to login via ssh to the container
- open the Dockerfile file and find the line containing 'chpasswd'
- change the default password to something unique

In the directory containing the Dockerfile file, run this commands
> docker build -t cms-cvmfs-docker .

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Starting the container for the first time

To run the container as a background daemon
> docker run -d -P --privileged --name cms-cvmfs -v <local directory on your machine containing files you want to access>:/root/<subdirectory in container to get files> cms-cvmfs-docker

To determine which port to use when doing ssh into the container
> docker port cms-cvmfs 22

the output should be something like
0.0.0.0:32768

Then to ssh into the container, use the obtained from the previous command, e.g.
> ssh root@0.0.0.0 -p 32768

Use the password you set in the Dockerfile

Run the following command the very first time you run the container in order to mount the cvmfs file system
> ./run.sh

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Setting up an CMSSW area

Once inside the container, you can setup the CMSSW area in the standard way

- do the initial setup to get the 'scram' command
> source /cvmfs/cms.cern.ch/cmsset_default.sh
- move to a directory you want to make a CMSSW work area
- see what CMSSW versions are available
> scram list -a CMSSW 
- setup a work area for a specific version, e.g.
> scram project CMSSW_8_0_0

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Stopping a container

After logging out of the ssh session in the docker container, you can temporarily stop the container daemon by doing
> docker stop cms-cvmfs

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Restarting a container

You can restart a container after it had been stopped by doing
> docker start cms-cvmfs

NOTE: after stopping and restarting a container, the port to use when doing ssh may have changed, make sure to rerun
> docker port cms-cvmfs 22

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Removing a container

If you decide you no longer need that particular container (perhaps you want to start another fresh one), you can delete that container instance by doing
> docker rm cms-cvmfs


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Acknowledgements

This work was based largely on the following work of others
https://twiki.cern.ch/twiki/bin/view/Main/DockerCVMFS
https://github.com/cms-sw/cms-docker/blob/master/cmssw/Dockerfile
http://cmsrep.cern.ch/cmssw/cms/slc6_amd64_gcc530-driver.txt