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Ansible Lint

Filesystem layer


The EESSI project uses the CernVM File System (CVMFS) for distributing its software. More details about CVMFS can be found at its homepage and documentation:

The following introductory video on Youtube gives a quite good overview of CVMFS as well:

CVMFS infrastructure

The CVMFS layer of the EESSI project consists of the usual CVMFS infrastructure:

  • one Stratum 0 server;
  • multiple Stratum 1 servers, which contain replicas of the Stratum 0 repositories;
  • multiple local Squid proxy servers;
  • CVMFS clients with the appropriate configuration files on all the machines that need access to the CVMFS repositories.

Installation and configuration


The main prerequisite is Ansible (, which can be easily installed via the package manager of most Linux distributions or via pip install. For more details, see the Ansible installation guide: Note that Ansible needs to be able to log in to the remote machines where you want to install some CVMFS component, and needs to be able to use privilege escalation (e.g. sudo) on those machines to execute tasks with root permission.

For the installation of all components we make use of two Ansible roles: the CVMFS installation role provided by the Galaxy project (see, and a role for adding the EPEL repository (

To download the dependency roles do:

ansible-galaxy role install -r requirements.yml -p ./roles


The EESSI specific settings can be found in inventory/group_vars/all.yml, and in templates we added our own templates of Squid configurations for the Stratum 1 and local proxy servers. For all playbooks you will also need to have an appropriate Ansible hosts file in the inventory folder; see the supplied inventory/hosts.example for the structure and host groups that you need for these playbooks.

Ansible offers several ways to override any configuration parameters. Of course you can edit a playbook or the all.yml file, but it is best to keep these files unmodified.

Machine-specific configuration

If the setting is for one specific machine (e.g. your Stratum 1 machine), it is recommended to make a file in the inventory/host_vars directory and use the machine name as name of the file. This file can contain any settings that should be overridden for this particular machine. See stratum0host.example in that directory for an example. Any other files that you will create in this directory will be ignored by git.

Site-specific configuration

Any other site-specific configuration items can go into a file inventory/local_site_specific_vars.yml (which will be ignored by git). We provided an example file that shows the kind of configuration that you should minimally provide. You can also add more items that you would like to override to this file. See the next section for instructions about passing your configuration file to the playbook.

Running the playbooks

In general, all the playbooks can be run like this:

ansible-playbook -b -e @inventory/local_site_specific_vars.yml <name of playbook>.yml

Here the option -e @/path/to/your/config.yml is used to include your site-specific configuration file. The -b option means "become", i.e. run with sudo. If this requires a password, include -K, which will ask for the sudo password when running the playbook:

ansible-playbook -b -K -e @inventory/local_site_specific_vars.yml <name of playbook>.yml

Before you run any of the commands below, make sure that you created a inventory/hosts file, a site-specific configuration file, and, if necessary, created machine-specific configuration files in inventory/host_vars.


To make all communication between the CVMFS services possible, some ports have to be opened on the Stratum 0 (default: port 80), Stratum 1 (default: port 80 and 8000), and local proxy (default: port 3128). These default port numbers are listed in roles/galaxyproject.cvmfs/defaults/main.yml, but can be overridden in your local configuration file (local_site_specific_vars.yml).

The Ansible playbook can update your firewall rules automatically (firewalld on Redhat systems, ufw on Debian systems), but by default it will not do this. If you want to enable this functionality, set cvmfs_manage_firewall to true.

Stratum 0

First install the Stratum 0 server:

ansible-playbook -b -K -e @inventory/local_site_specific_vars.yml stratum0.yml

Note that there can be only one Stratum 0, so you should only run this playbook for testing purposes or in case we need to move or redeploy the current Stratum 0 server.

An additional playbook create_cvmfs_content_structure.yml, which runs the Ansible role roles/create_cvmfs_content_structure, can be used to automatically deploy certain files and symlinks to the EESSI CVMFS repositories. The list of files and symlinks can be defined in roles/create_cvmfs_content_structure/vars, where you can add files <name of the CVMFS repo>.yml. A cron job can be used on the Stratum 0 or a publisher node to periodically check for changes in these files, and to push updates to your repo. In order to do this, clone this filesystem-layer repository, and let your cron job do a git pull followed by a run of the playbook (e.g. ansible-playbook --connection=local create_cvmfs_content_structure.yml).

Stratum 1

Installing a Stratum 1 requires a GEO API license key, which will be used to find the (geographically) closest Stratum 1 server for your client and proxies. More information on how to (freely) obtain this key is available in the CVMFS documentation: .

You can put your license key in the local configuration file inventory/local_site_specific_vars.yml.

Furthermore, the Stratum 1 runs a Squid server. The template configuration file can be found at templates/eessi_stratum1_squid.conf.j2. If you want to customize it, for instance for limiting the access to the Stratum 1, you can make your own version of this template file and point to it by overriding the following setting in inventory/local_site_specific_vars.yml. See the comments in the example file for more details.

Install the Stratum 1 using:

ansible-playbook -b -K -e @inventory/local_site_specific_vars.yml stratum1.yml

This will automatically make replicas of all the repositories defined in group_vars/all.yml.

Local proxies

The local proxies also need a Squid configuration file; the default can be found in templates/localproxy_squid.conf.j2. If you want to customize the Squid configuration more, you can also make your own file, and point to in inventory/local_site_specific_vars.yml. See the comments in the example file for more details.

Furthermore, you have to define the lists of IP addresses / ranges (using CIDR notation) that are allowed to use the proxy using the variable local_cvmfs_http_proxies_allowed_clients. Again, see inventory/local_site_specific_vars.yml.example for more details.

Do keep in mind that you should never accept proxy request from everywhere to everywhere! Besides having a Squid configuration with the right ACLs, it is recommended to also have a firewall that limits access to your proxy.

Deploy your proxies using:

ansible-playbook -b -K -e @inventory/local_site_specific_vars.yml localproxy.yml


Method 1: Ansible

Make sure that your hosts file contains the list of hosts where the CVMFS client should be installed. Furthermore, you can define a list of (local) proxy servers that your clients should use in inventory/local_site_specific_vars.yml using the parameter local_cvmfs_http_proxies. See inventory/local_site_specific_vars.yml.example for more details. If you just want to roll out one client without a proxy, you can leave this out.

Finally, run the playbook:

ansible-playbook -b -K -e @inventory/local_site_specific_vars.yml client.yml

Method 2: Packages

On many operating systems the CVMFS client can be installed through your package manager. For details, see the Getting Started page in the documentation.

After installing the client, you will have to configure it. For this you can use the CVMFS configuration packages that we provide for clients. These packages can be found on the Releases page. Download the package for your operating system, and install it, e.g.:

rpm -i cvmfs-config-eessi-*.rpm
dpkg -i cvmfs-config-eessi-*.deb

NB! We now also have a yum repository where you can install the configuration package from. If you opt for this solution you will get automatic updates. Instead of downloading the rpm as above, you run the following commands:

sudo yum -y install
sudo yum check-update
sudo yum -y install cvmfs-config-eessi

Next, you need to make a file /etc/cvmfs/default.local manually; this file is used for local settings and contains, for instance, the URL to your local proxy and the size of the local cache. As an example, you can put the following in this file, which corresponds to not using a proxy and setting the local quota limit to 40000MB:


If you do want to use your own proxy, replace the first line by:

CVMFS_HTTP_PROXY=<hostname of your proxy>:<port>

For more details about configuring your client, see

Finally, run cvmfs_config setup to set up CVMFS.

Admin note: for building the client configuration packages, see this section.

Verification and usage


Once the client has been installed, you should be able to access all repositories under /cvmfs. They might not immediately show up in that directory before you have actually used them, so you might first have to run ls, e.g.:

ls /cvmfs/

On the client machines you can use the cvmfs_config tool for different operations. For instance, you can verify the file system by running:

$ sudo cvmfs_config probe
Probing /cvmfs/ OK

Checking for misconfigurations can be done with:

sudo cvmfs_config chksetup

In case of unclear issues, you can enable the debug mode and log to a file by setting the following environment variable:


Proxy / Stratum 1

In order to test your local proxy and/or Stratum 1, even without a client installed, you can use curl. Leave out the --proxy http://url-to-your-proxy:3128 if you do not use a proxy.

curl --proxy http://url-to-your-proxy:3128 --head http://url-to-your-stratum1/cvmfs/

This should return:

HTTP/1.1 200 OK
X-Cache: MISS from url-to-your-proxy

The second time you run it, you should get a cache hit:

X-Cache: HIT from url-to-your-proxy

Example with the Norwegian Stratum 1:

curl --head

Using the CVMFS infrastructure

When the infrastructure seems to work, you can try publishing some new files. This can be done by starting a transaction on the Stratum 0, adding some files, and publishing the transaction:

sudo cvmfs_server transaction
mkdir /cvmfs/
touch /cvmfs/
sudo cvmfs_server publish

It might take a few minutes, but then the new file should show up at the clients.

Building the CVMFS configuration packages

For each push and pull request to the main branch, packages are automatically built by a Github Action. The resulting (unversioned) packages can be found as build artifacts on the page of each run of this action. When a new tag is created to mark a versioned release of the repository (e.g. v1.2.3, where the v is required!), the action builds a package with the same version number, creates a release, and stores the packages as release assets.


The software in this repository is distributed under the terms of the GNU General Public License v2.0.

See LICENSE for more information.

SPDX-License-Identifier: GPL-2.0-only