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The Halo measurement system is built using Bazel. The resulting container images are designed to run in Kubernetes clusters.

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Requirements

Your build environment must have the following components:

Bazel

Version 7.7.1 (see .bazelversion)

Operating System

GNU/Linux with x86-64 architecture

Clang

Required for C++ compilation

SWIG

Interface generation tool
Some image targets require building with glibc ≤ 2.36. Known compatible platforms include Debian Bookworm and Ubuntu 22.04.

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Additional Dependencies

  • Bash - Shell scripting
  • OpenSSL 1.1.1+ - Cryptographic operations
All executable dependencies must be in your $PATH.

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Quick Start

1

Run all tests

Verify your environment is set up correctly:
bazel test //src/test/...
2

Specify host platform

Some targets require explicit platform specification:
bazel build --host_platform=//build/platforms:ubuntu_22_04 //your/target
Compatible platforms are defined in //build/platforms/BUILD.bazel.
Bazel cannot auto-detect glibc versions, so you must explicitly specify the --host_platform option for targets requiring glibc ≤ 2.36.

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Make Variables

Some build targets use “Make” variables defined via the --define option. These can be set on the command line or in .bazelrc. 
bazel build --define=variable_name=value //your/target
Variable definitions are located in build/variables.bzl.

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Containerized Builds

If your host machine doesn’t meet the requirements, use the containerized build environment.

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Using the Container Script

The ghcr.io/world-federation-of-advertisers/bazel container image provides a complete build environment. Use the tools/bazel-container script as a drop-in replacement for the bazel command: 
tools/bazel-container test //src/test/...
The tools/bazel-container script automatically specifies the appropriate host platform, so you should not use the --host_platform option when using it.

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Interactive Container Shell

For extensive development work, you can run a shell inside the container: 
docker run -it --rm \
  -v "$PWD":/workspace \
  -w /workspace \
  ghcr.io/world-federation-of-advertisers/bazel \
  /bin/bash
You can even install IntelliJ IDEA inside the container and use X11 forwarding to access it from your host.

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TestContainer-based Tests

Running tests that use TestContainers inside Docker requires additional setup: The tools/bazel-container script handles these configurations automatically.

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Hybrid Development

If your host has a newer glibc version but meets other requirements, you can develop locally and use the container only for building/deploying images.

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Running Container-Built Targets on Host

On Linux, the tools/bazel-container script writes output to bazel-container-output in your working directory. Use the tools/bazel-container-run script to generate executable scripts: 
tools/bazel-container-run //your/target
This creates a script you can execute on your host machine.

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Build Targets

Test All

bazel test //src/test/...

Build Images

bazel build //path/to:image_target

Run Target

bazel run //path/to:target

Container Build

tools/bazel-container build //target

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Local Kubernetes

You can deploy a minimal testing environment in a local Kubernetes cluster for development and testing purposes.

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Next Steps

Testing

Learn how to run and organize tests

IntelliJ Setup

Configure your IDE for development

Build docs developers (and LLMs) love

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