workflows/eval: load supportedSystems from JSON file

    if: needs.get-merge-commit.outputs.mergedSha

    outputs:

      targetSha: ${{ steps.targetSha.outputs.targetSha }}

      systems: ${{ steps.systems.outputs.systems }}

    steps:

      - name: Check out the PR at the test merge commit

        uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2

        with:

          extra_nix_config: sandbox = true

      - name: Evaluate the list of all attributes and get the systems matrix

        id: systems

      - name: Evaluate the list of all attributes

        run: |

          nix-build nixpkgs/ci -A eval.attrpathsSuperset

          echo "systems=$(<result/systems.json)" >> "$GITHUB_OUTPUT"

      - name: Upload the list of all attributes

        uses: actions/upload-artifact@ea165f8d65b6e75b540449e92b4886f43607fa02 # v4.6.2

    strategy:

      fail-fast: false

      matrix:

        system: ${{ fromJSON(needs.attrs.outputs.systems) }}

        system: ${{ fromJSON(needs.get-merge-commit.outputs.systems) }}

    steps:

      - name: Enable swap

        run: |

      mergedSha:

        description: "The merge commit SHA"

        value: ${{ jobs.resolve-merge-commit.outputs.mergedSha }}

      systems:

        description: "The supported systems"

        value: ${{ jobs.resolve-merge-commit.outputs.systems }}

permissions: {}

    runs-on: ubuntu-24.04-arm

    outputs:

      mergedSha: ${{ steps.merged.outputs.mergedSha }}

      systems: ${{ steps.systems.outputs.systems }}

    steps:

      - uses: actions/checkout@11bd71901bbe5b1630ceea73d27597364c9af683 # v4.2.2

        with:

              fi

              ;;

          esac

          rm -rf base

      - name: Load supported systems

        id: systems

        run: |

          echo "systems=$(jq -c <base/ci/supportedSystems.json)" >> "$GITHUB_OUTPUT"

  --arg evalSystems '["x86_64-linux" "aarch64-darwin"]'

```

- `--max-jobs`: The maximum number of derivations to run at the same time. Only each [supported system](../supportedSystems.nix) gets a separate derivation, so it doesn't make sense to set this higher than that number.

- `--max-jobs`: The maximum number of derivations to run at the same time. Only each [supported system](../supportedSystems.json) gets a separate derivation, so it doesn't make sense to set this higher than that number.

- `--cores`: The number of cores to use for each job. Recommended to set this to the amount of cores on your system divided by `--max-jobs`.

- `chunkSize`: The number of attributes that are evaluated simultaneously on a single core. Lowering this decreases memory usage at the cost of increased evaluation time. If this is too high, there won't be enough chunks to process them in parallel, and will also increase evaluation time.

- `evalSystems`: The set of systems for which `nixpkgs` should be evaluated. Defaults to the four official platforms (`x86_64-linux`, `aarch64-linux`, `x86_64-darwin` and `aarch64-darwin`).

          "nixos"

          "pkgs"

          ".version"

          "ci/supportedSystems.nix"

          "ci/supportedSystems.json"

        ]

      );

    };

  nix = nixVersions.nix_2_24;

  supportedSystems = import ../supportedSystems.nix;

  supportedSystems = builtins.fromJSON (builtins.readFile ../supportedSystems.json);

  attrpathsSuperset =

    runCommand "attrpaths-superset.json"

          nix

          time

        ];

        env.supportedSystems = builtins.toJSON supportedSystems;

        passAsFile = [ "supportedSystems" ];

      }

      ''

        export NIX_STATE_DIR=$(mktemp -d)

            --option restrict-eval true \

            --option allow-import-from-derivation false \

            --arg enableWarnings false > $out/paths.json

        mv "$supportedSystemsPath" $out/systems.json

      '';

  singleSystem =

[

  "aarch64-linux",

  "aarch64-darwin",

  "x86_64-linux",

  "x86_64-darwin"

]