Bootstrap GCC, LLVM and NVHPC, and build an HPC software stack based on OpenMPI, with a few unique features:

1. parallel package builds with single jobserver for all builds;
2. avoiding relocation issues by fixing the install path to a new directory /some-dir of choice (no root access required);
3. fast, in-memory builds.

Requirements:

• spack
• bwrap (when not already building inside a sandbox)

Usage:

1. Copy Make.user.example to Make.user and change some variables.
2. Run make -j$(nproc) to bootstrap compilers and packages.
3. Run make store.squashfs to bundle those in a squashfs file.
4. Run make build.tar.gz to create a tarball of all concrete environments and generated config files for posterity. This excludes the actual software.

Variables

A few variables in Make.user:

• STORE: where to install packages;
• SPACK: what spack to use;
• SPACK_SYSTEM_CONFIG_PATH: path to spack config dir (e.g. config/hohgant).
• SANDBOX: run commands in a sandbox (e.g. bubblewrap), see Make.user.example for details.
• SPACK_INSTALL_FLAGS: specify more install flags, like --verbose.

Reproducibility

When building on a production system instead of in a sandbox, there's a few things to do to improve reproducibility:

1. Always run make inside a clean environment:

   env --ignore-environment PATH=/usr/bin:/bin make
   

2. Update Make.user to hide your home folder so that no user config is picked up:

   SANDBOX := bwrap --tmpfs ~ ...
   

3. Set LC_ALL, TZ and SOURCE_DATE_EPOCH to something fixed in Make.user.

Unprivileged mounts

The squashfs file can then be mounted using squashfs-mount or squashfuse