This repository contains a collection of Nix library functions and packages focused on benchmarking Nix build infrastructure. They are implemented to test nixbuild.net, but can also be used for testing generic Nix build servers.

Writes a single file of random bytes to $out. The build is configured by using the environment variables listed below, and must be run with the --impure Nix option.

DRV_SEED: [Mandatory, String] Sets a seed for the derivation, used for forcing rebuild.

FILE_SEED: [Optional, Integer, default=0] Specifies a random seed used for generating the file contents. If FILE_SEED and FILE_SIZE are the same between builds, the output nar hash will be the same.

FILE_SIZE: [Optional, Integer, default=1] Specifies the size of the file, in (Base 10) megabytes.

COMPRESS_PERCENT: [Optional, Integer, default=50] Specifies the percentage of the file that is compressible. So if you specify 80, it is expected that the resulting file can be compressed to 20% of its original size.

ID: [Optional, String, nixbuild.net] Sets the nixbuild.net tag ID of the generated derivation.

CPUS: [Optional, Integer, default=2, nixbuild.net] Sets the number of CPUs nixbuild.net should allocate for the build.

Run 4 builds concurrently, each one creating a 10 MB output file:

$ seq 1 4 | xargs -I '{}' -P0 \
    env DRV_SEED="$RANDOM{}" FILE_SIZE=10 ID="BENCH_A" \
      nix build .#write-one-file \
        --impure \
        --eval-store auto \
        --store ssh-ng://eu.nixbuild.net

We can now use the nixbuild.net API to query about the builds:

$ curl -s -H "Authorization: Bearer $NIXBUILDNET_TOKEN" \
    "https://api.nixbuild.net/builds?tags=ID:BENCH_A" \
      | jq '.[].duration_seconds'

0.474567
0.470182
0.474698
0.479252