UENV 2

Documentation for uenv2 is available on the new cscs documentation.

A rewrite of uenv in C++:

• deployed as static binaries
• no longer supports modification of the environment in the calling shell
• bring the CLI and Slurm plugin under one roof, with a common library

Some old features are gone:

• uenv view and uenv modules have been removed - the tool can no longer modify the environment of the calling shell
  • all views must be loaded with the --view flag on uenv run and uenv start
  • or using the --view flag of srun and sbatch.

Alps quickstart

Before running the build script, install uv, which is used to provide meson and ninja for the build.

To take uenv2 for a test drive on alps,

git clone https://github.com/eth-cscs/uenv2.git

cd uenv2

# this script will build uenv2, and install it in $HOME/.local/$(uname -m)/bin
./install-alps-local.sh

building

The software uses meson wrap to bring its own dependencies, all of which are built as static libraries.

To build you only need

• meson >= 1.5
• ninja
• g++ that supports C++20 (we test g++12 regularly)

On your laptop these requirements can be met using your package manager of choice.

On an Alps vCluster, we want to use the system compiler "as is" without using a uenv or modules. The g++ requirement is met by the g++-12 compiler, that is installed on the vClusters as part of the boot image.

On Alps the version of Python3 is too ancient to support the required meson version. Install uv to use appropriate Python and meson versions.

alias e="uvx --with meson,ninja"
CXX=g++-12 e meson setup -Dtests=enabled build
e meson compile -Cbuild

• use the system version of gcc-12 in order to create a statically linked binary that can run outside the uenv

testing

There are three sets of tests:

• unit: unit tests for the C++ library components (Catch2)
• cli: tests for the CLI interface (bats)
• slurm: tests for the Slurm plugin (bats)

To build tests, use the -Dtests=enabled flag to meson

meson setup -Dtests=enabled

The tests are installed in the test sub-directory of the build path:

cd build/test

# run the unit tests
./unit

# run the cli tests
./bats cli.bats

The tests can also be run using meson:

# run all the tests
meson test

# or run test suites separately
meson test cli
meson test unit

NOTE: the slurm integration tests require configuring Slurm to use the plugin, which requires root permissions. For this reason, they can't be tested on Alps vClusters.