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Building Labs

The Lab is the central artifact in RepX. It is a directory structure produced by Nix that contains everything needed to execute your experiment.

The Build Command​

To build the lab, run:

nix build

This command looks for the default package output in your flake.nix.

What's Inside the Lab?​

The output is typically a symlink named result.

result/
├── lab/
│   ├── manifest.json       # Complete experiment topology
│   └── runs.json           # List of defined runs
├── jobs/
│   └── <job_hash>/         # One directory per unique job
│       ├── script          # The executable script
│       ├── env             # The software environment (closure)
│       └── metadata.json   # Job-specific metadata
├── host-tools/             # Static binaries for bootstrapping
└── revision/               # Git commit hash and dirty status

Reproducibility Guarantees​

Because the Lab is built by Nix:

  1. Software Environment: Exact versions of all tools (Python, compilers, libraries) are locked.
  2. Scripts: Your stage scripts are part of the build.
  3. Parameters: All parameters are baked into the job definitions.

If you copy this result directory to another machine (that has Nix or the host-tools compatible with the target), you can run the exact same experiment.