Bibliography

LaTeX documents that use \cite{} need a bibliography processor. Modern documents almost always want biblatex + biber, which handle Unicode, sophisticated styles, and multi-bibliography workflows correctly.

rules_latex ships a vendored biber binary alongside the tectonic toolchain. To use it, set biber = True on your document.

Minimal example

% paper.tex
\documentclass{article}
\usepackage[backend=biber,style=numeric]{biblatex}
\addbibresource{references.bib}

\begin{document}
This sentence cites Knuth~\cite{knuth1984}.
\printbibliography
\end{document}

% references.bib
@book{knuth1984,
  author = {Donald E. Knuth},
  title  = {The {{\TeX}}book},
  publisher = {Addison-Wesley},
  year = {1984},
}

# BUILD.bazel
load("@rules_latex//latex:defs.bzl", "latex_document")

latex_document(
    name = "paper",
    main = "paper.tex",
    srcs = ["paper.tex", "references.bib"],
    biber = True,
)

bazel build //:paper

The build runs tectonic, biber, tectonic again — all sandboxed, all hermetic. The resulting PDF has resolved citations.

How it works

When biber = True:

1. The platform-specific biber binary from the toolchain is staged into a per-action scratch directory.
2. That directory is prepended to PATH inside the sandbox.
3. Tectonic's biblatex subprocess resolves biber by basename and shells out to it as usual.

The biber binary is vendored from a GitHub release mirror on the rules_latex repo, content-addressed by SHA-256. See DESIGN.md §4.9 for the full implementation details.

Version coupling

Biber is tightly coupled to biblatex's "control file format" version. rules_latex pins biber 2.21 to match the biblatex 3.21 that ships in the self-hosted TeX Live 2026 bundle. The pin and the bundle are bumped together, so the pair can never drift — you don't manage it.

Citation styles not in the bundle

The bundle ships the standard biblatex styles (numeric, alphabetic, authoryear, authortitle, verbose). Extension styles — APA, Chicago, IEEE, Nature, Vancouver, etc. — live in separate CTAN packages. Add them with the ctan_packages attribute; no toolchain opt-in is needed, because the bundle's biblatex 3.21 is new enough to process them.

Modern citation styles

Just list the style package in ctan_packages and turn on biber:

latex_document(
    name = "thesis",
    main = "thesis.tex",
    srcs = ["thesis.tex", "references.bib"],
    ctan_packages = ["biblatex-apa"],   # APA 7th edition style
    biber = True,
)

% thesis.tex
\usepackage[style=apa]{biblatex}

Modern extension styles (apa.bbx, chicago.bbx, …) need biblatex 3.18+ / biber 2.18+; the TeX Live 2026 bundle ships 3.21 / 2.21, so they work with no extra configuration. See the CTAN packages page for the full version-coupling discussion.

Upgrading from ≤ v0.5? Earlier versions required a tectonic.toolchain(modern_biblatex = True) opt-in for these styles. It was removed in v0.6.0 — the rebuilt bundle ships the modern stack natively. Delete that argument from your MODULE.bazel.

Biber binary availability

Platform	Toolchain biber?	Note
Linux x86_64		Upstream prebuilt
Linux aarch64		Prebuilt biber 2.21 (CTAN)
macOS x86_64		Native Intel binary
macOS aarch64		Native Apple Silicon binary
Windows x86_64	Binary available	Native rules_latex workflows are not yet supported or CI-tested.

On macOS, the toolchain downloads only the native slice of upstream Biber 2.21. The original Developer ID signature and notarization are preserved. Biber startup does not require Xcode or lipo; this avoids the universal launcher's incompatible lipo -extract_family call with newer Xcode tools. No BUILD-file changes or system Biber installation are needed.

Unsupported platforms

biber 2.21 is vendored for the supported Linux and macOS platforms above, including Linux arm64 (a prebuilt binary from CTAN's biber-linux-aarch64 package, new in v0.6.0). If you're on a platform without a vendored binary, install biber via your distro (apt-get install biber) and fall back to the system binary on PATH:

latex_document(
    name = "thesis",
    main = "thesis.tex",
    srcs = [...],
    biber = True,
    biber_strategy = "system",   # use system biber on PATH
)

This is less hermetic — your build depends on whatever biber is installed — so it's an escape hatch, not the recommended path.