Content Distribution
This page documents usage of the CVMFS service operated for EGI by RAL.
Overview
The CernVM-File System (CVMFS) provides a scalable, reliable and low-maintenance
software distribution service. It was developed to assist High Energy Physics
collaborations to deploy software on the worldwide distributed computing
infrastructure used to run data processing applications. CVMFS is implemented as
a POSIX read-only file system in user space. Files and directories are hosted on
standard web servers and mounted in the universal namespace /cvmfs. CernVM-FS
uses outgoing HTTP connections only, thereby it avoids most of the firewall
issues of other network file systems. It transfers data and metadata on demand
and verifies data integrity by cryptographic hashes. CVMFS is actively used by
small and large collaborations. In many cases, it replaces package managers and
shared software areas on cluster file systems as means to distribute the
software used to process experiment data.
This documentation is for the VO content managers.
Official CVMFS pages
Requesting the creation of a new repository
In the case of a new repository for EGI, steps are described in PROC22.
Onboarding new Content Managers
Steps for a new VO Content Manager to be granted access to the Stratum-0.
Requesting access
Request access to the service sending an email to cvmfs-support@gridpp.rl.ac.uk In the email, include the following information:
- Name of the VO or CVMFS repository.
- Your Check-in ID from EGI Check-in.
Mailing list
All VO content managers should join the CVMFS-UPLOADER-USERS mailing list in JISCMAIL.
Distributing new content
To log into the service, just use ssh.
You need to specify explicitly which username you want to use to log in.
The username is composed as reponame+"sgm".
For example, for the repository dirac.egi.eu, the username is diracsgm.
# Replace with the proper username
$ ssh diracsgm@cvmfs-upload01.gridpp.rl.ac.uk
To copy data:
# Replace with the proper username
$ scp source_file.txt diracsgm@cvmfs-upload01.gridpp.rl.ac.uk:destination_folder/
When running the ssh or scp commands, a message like this is displayed:
# Replace with the proper username
$ ssh diracsgm@cvmfs-upload01.gridpp.rl.ac.uk
Authenticate at
-----------------
https://aai.egi.eu/device?user_code=AAAAA-BBBBB
-----------------
Hit enter when you have finished authenticating
Copy and paste the URL into a browser, and follow the instructions to authenticate yourself using your home institution Identity Management Service.
After login, you will find a single directory in the home directory:
$ ls
cvmfs_repo
Add to that directory the new content you want to distribute.
Files and directories cannot be distributed with CVMFS if they are not world-wide readable. You may want to ensure they have the right permissions with the following commands:
$ find . -type d -exec chmod go+rx {} \;
$ find . -type f -exec chmod go+r {} \;
Building your software
CVMFS is an infrastructure to distribute software world-wide. However, the uploader host should not be used for the purposes of building and compiling it prior to distribution.
The right approach is for you to have your own local building environment, and use the uploader host only to upload the new content for distribution.
If you have non-relocatable software, then you will need a /cvmfs/<myrepo>/
directory on your building host. One option is to use an actual CVMFS client, so
you have ready all the existing content being already distributed by CVMFS. By
default, the /cvmfs/ directory on a CVMFS client host is read-only, but that
can be solved using an
ephemeral writable container.