alice.bits

Recipes and defaults for building the ALICE software stack (O2, O2Physics and their dependencies) with bits. This repository is thin: the ALICE recipes themselves live in alisw/alidist, which the bits-providers registry exposes as the shared recipe pool alidist.bits. alice.bits adds what bits needs on top of it: the base defaults with the ALICE CVMFS layout, the aliBuild-compatible alidist variant and two temporary recipe fixes (see Files). Everything else (O2, O2Physics, ROOT, the defaults o2, o2-epn, ...) comes from alidist.

Two ways to build ALICE software

bits can be driven in two ways (see Front-end choice in the bits reference):

• Native bits with alice.bits (recommended, and what the bits-console CI uses). bits loads the provider registry, which brings in alidist at the branch the registry names (master), together with the fixes and the CVMFS layout in this repository.
• The aliBuild front-end with an alidist checkout (legacy). The aliBuild script shipped with bits keeps the classic workflow: no registry, recipes from a local alidist checkout, legacy init.sh, VO_ALICE@pkg::version names in aliBuild q and the alisw/<distro>-builder images for --docker. This repository is not used on that path.

Prerequisites

• bits installed as described in the bits README; this also puts the aliBuild wrapper on your PATH. Check the machine with bits doctor.

• A platform alidist supports. The bits-console ALICE builds use these architectures and builder images:

  Platform	--architecture	Builder image
  EL9, x86-64	slc9_x86-64	registry.cern.ch/alisw/slc9-builder
  EL9, ARM64	slc9_aarch64	registry.cern.ch/alisw/slc9-arm-builder
  EL8, x86-64	slc8_x86-64	docker.io/alisw/slc8-builder
  Ubuntu 22.04, x86-64	ubuntu2204_x86-64	registry.cern.ch/alisw/ubuntu2204-builder
  Ubuntu 24.04, x86-64	ubuntu2404_x86-64	registry.cern.ch/alisw/ubuntu2404-builder

  Use these aliBuild-style names: the alidist recipes test $ARCHITECTURE and only recognise slc* and ubuntu* values. On a matching host bits detects them itself. EL10 and Ubuntu 26.04 are not supported by alidist yet.

• O2Physics is large: the alidist variant allows 5 GiB per compile job for it, so plan on enough memory for the number of jobs you run (see Build memory-hungry packages).

Getting started with native bits

Work in a directory that holds the recipe checkout, your development checkouts and the sw work directory side by side, as with aliBuild:

mkdir alice && cd alice
bits init alice.bits                  # or: git clone https://github.com/bitsorg/alice.bits
bits use build -c alice.bits --defaults alidist::o2
bits build --dry-run O2Physics        # optional: what would be reused and what built
bits build O2Physics                  # alidist is fetched automatically
bits enter O2Physics/latest           # sub-shell with O2Physics loaded; leave with `exit`

bits use build records the options once for this directory (saved in ./.bitsuse). For a container build, record instead, e.g. on an EL9 x86-64 host: bits use build -c alice.bits --defaults alidist::o2 --architecture slc9_x86-64 --docker --docker-image registry.cern.ch/alisw/slc9-builder. To build elsewhere, export BITS_WORK_DIR=/path/to/sw.

--defaults alidist::o2 loads release and the alidist variant (both from this repository) and alidist's o2 defaults. O2 builds the same way. Pick another alidist flavour by replacing o2, e.g. alidist::o2-epn; packages reject flavours they do not list in their valid_defaults.

To develop a package, check out its source next to the recipes and rebuild; this works for packages whose recipe is in alidist too:

bits init -c alice.bits --defaults alidist::o2 O2Physics   # writable checkout in ./O2Physics
bits build O2Physics                  # builds your checkout

Getting started with aliBuild

mkdir alice && cd alice
aliBuild init                         # clone alisw/alidist into ./alidist
aliBuild build O2Physics --defaults o2
aliBuild init O2Physics               # optional: development checkout
bits enter O2Physics/latest

aliBuild --docker uses the alisw/<distro>-builder image for the architecture by default. The build-time environment is the classic aliBuild one, so bits and aliBuild produce the same package hashes and can share tarballs.

Notes for ALICE users

• CVMFS layout. Published packages go to /cvmfs/bits.cern.ch/alice/<install-dir>/Packages/<pkg>/<version>, with modulefiles in /cvmfs/bits.cern.ch/alice/<install-dir>/Modules/modulefiles/<pkg> and architecture-independent packages under /cvmfs/bits.cern.ch/alice/noarch/. The install directory follows the OS-first ALICE convention (el9-x86_64, el9-aarch64, ubuntu2404_x86_64), not the architecture string. The prefix /cvmfs/bits.cern.ch/alice must match the cvmfs_prefix that bits-console sets for ALICE; a build whose prefix disagrees refuses to publish.
• Publishing is done from bits-console, which builds with --defaults alidist::<flavour> on the platforms above. To check where a package would land, use bits cvmfs-path.
• Changing defaults. Compiler flags, disabled packages and version pins come from the alidist flavour (defaults-o2.sh, ...); change them in alidist. This repository holds only the CVMFS layout and the bits-specific build settings. Its defaults-release.sh must stay: it hides alidist's file of the same name, the legacy ROOT 5 flavour, which aliBuild never loads under --defaults o2.

Files

File	Role
defaults-release.sh	Base of every chain: the ALICE CVMFS layout and requires: alidist.bits, so every build pulls in alidist. Nothing else; it replaces alidist's legacy defaults-release.sh.
defaults-alidist.sh	The aliBuild-compatible build variant: legacy build-time init.sh (alidist-compatible hashes), CMAKE_PREFIX_PATH exported at build time, and 5 GiB of memory per compile job for O2Physics.
grpc.sh, vecgeom.sh	Temporary copies of the alidist recipes with a build fix each. Because this repository is searched before alidist, they shadow the alidist versions; they will be removed once the fixes are merged upstream.

More information

• alisw/alidist: the ALICE recipes; bits-providers: the registry entries alice.bits and alidist.bits
• bits ALICE: the aliBuild workflow, Check out a recipe repository and develop against it, Docker Support
• bits User Guide, Cookbook, Reference
• bits-console: CI builds and CVMFS publishing

License

This repository does not contain a LICENSE file yet.