Compatibility layer

Introduction

The compatibility layer of the EESSI project uses Gentoo Prefix to provide a known base on top of the host. This is the foundation we use to build our software stack on. An alternative would be the NixOS.

Installation and Configuration

Prerequisites

The bootstrap process will need a clean environment with C and C++ compilers (the system version of gcc and g++ will do) as well as the make command. It also is very sensitive to the environment, so setup a user with unset CFFLAGS, CFLAGS, LDFLAGS, PKG_CONFIG_PATH and the always harmful LD_LIBRARY_PATH variables.

EESSI provides a Singularity container for this.

Building the Singularity container

The provided Singularity definition file can be used to build a container with a clean environment:

sudo singularity build bootstrap-prefix.sif singularity-bootstrap-prefix.def

Bootstrapping Gentoo Prefix

Gentoo Prefix provides a bootstrap script to build the prefix, see Gentoo Prefix Bootstrap. We forked this version and made some modifications. See issue #8 for more details.

You can run our version of the bootstrap script (see bootstrap-prefix.sh) inside the Singularity container by executing:

singularity run bootstrap-prefix.sif

or simply:

./bootstrap-prefix.sif

If you want to run your own version of the bootstrap script, use:

singularity exec bootstrap-prefix.sif ./bootstrap-prefix.sh

After starting the bootstrap have a long coffee...

Adding EESSI overlay

Additional packages are added in the EESSI overlay, which is based on ComputeCanada. To add the overlay:

Start the prefix

startprefix

Ensure the configuration directory exists, with ${EPREFIX} the path to your prefix installation.

export EPREFIX=path/to/your/prefix
mkdir ${EPREFIX}/etc/portage/repos.conf

Configure the overlay.

emerge eselect-repository
eselect repository add eessi git https://github.com/EESSI/gentoo-overlay.git

Sync the overlay

emerge --sync

Ansible playbook

The steps described above can be automatically executed by running the Ansible playbook install.yml inside the folder playbooks. See the README in that folder for more details.

Updating the Prefix

Packages

Updating packages can be as easy as

emerge --sync
emerge

If you run into problems, usually a newer ebuild is not suited to build in a prefix environment. Try to mask latest versions:

Create a mask file if not existing and mask newer versions from thin provisioning tools greater or equal to 0.7.6:

echo ">=sys-block/thin-provisioning-tools-0.7.6" >> ${EPREFIX}/etc/portage/package.mask

Portage

Updating Portage requires the kernel source which corresponds to your running kernel on the host. Emerge will detect it in /usr/src/linux.

Check your running kernel version with:

cat /proc/version
Linux version 4.20.0-1.el7.elrepo.x86_64 (mockbuild@Build64R7) 

On a Centos 7 host kernel sources are installed in /usr/src/kernels. Link /usr/src/linux to the appropiate kernel source after installation. Example for an elrepo kernel:

rpm -ivh kernel-ml-devel-4.20.0-1.el7.elrepo.x86_64.rpm
cd /usr/src ; ln -s kernels/4.20.0-1.el7.elrepo.x86_64 linux

When ready update Portage from the Prefix environment:

startprefix
emerge --oneshot sys-apps/portage