A virtual GPU hall for testing bring-up tooling without hardware. One ground-truth model serves the devices a bring-up tool talks to, with fault injection and technician actions: Redfish BMCs, LLDP tables on Arista (eAPI) and NVIDIA (NVUE) leaves, DCGM exporters, and a minimal NetBox API. Apache-2.0.

pip install simhall turnup-check
simhall serve --golden hall-b &                                      # 127.0.0.1:8900, any token
turnup-check --site hall-b --intent http://127.0.0.1:8900/netbox

reading intent      288 links · 18 nodes · 2 leaves
polling             lldp · redfish · dcgm
✓ 287 / 288 links match intent
✓ 18 / 18 nodes reachable, firmware baseline ok
✗ mismatch   node7 mlx5_3 → leaf4/22
             expected leaf4/21
fix          move cable one port up
elapsed      0.4 s

A technician seats the cable, and the same command exits 0 with 288 / 288:

simhall act '{"kind":"seat_cable","label":"CBL-12-07-03","b_interface":"swp21"}'

Everything here is synthetic: no real hostnames, IPs, serial numbers or topologies. The intent it emits carries simulated: true, so a simulated run never counts as a real one.

Bring-up tooling is tested on the hardware it is meant to verify, which is the hardware nobody can spare. simhall gives a tool like turnup-check a hall that behaves like the real protocols at every layer, where any fault can be injected, observed through every view at once, and cleared again byte for byte. The test suite of turnup-check runs thousands of random halls and fault sets against it in-process.

pip install simhall                                     # Python 3.12+
pip install git+https://github.com/turnup-dev/simhall   # or straight from this repository

From a checkout: pip install -e '.[dev]', then simhall --help. Dependencies: fastapi, uvicorn, pydantic v2, httpx, pyyaml, click; pynetbox only for simhall seed-netbox (.[netbox]).

Actions (seat_cable, unseat_cable, power_on, power_off, replace_node, update_firmware, scan_qr) change the hall the way a technician would and retire the faults they physically resolve. Faults are applied on top of the base state and clearing one restores the views exactly, in any order. The complete tables and the rules are in docs/faults.md.

from simhall import HallSpec, Hall, Fault, Action

hall = Hall.generate(HallSpec(site="hall-b", racks=1, nodes_per_rack=18, ports_per_node=16,
                              leaves_per_rack=2, switch_vendor="nvidia", seed=1))
hall.inject(Fault(kind="wrong_port", cable="CBL-12-07-03", to_device="leaf4", to_interface="swp22"))
hall.lldp_table("leaf4")        # what the leaf would say
hall.redfish_tree("node7")      # what the BMC would say
hall.act(Action(kind="seat_cable", label="CBL-12-07-03", b_interface="swp21"))

create_app(hall) serves that very object over HTTP, so in-process actions are visible to a tool polling it. The model, the cabling rule and how state is derived: docs/model.md.

• docs/protocols.md: every endpoint served, by protocol, and the per-device fault modes.
• docs/model.md: HallSpec, Hall, the cabling rule, base and derived state.
• docs/faults.md: all faults, actions and their HTTP status codes.
• docs/specs.md: the golden scenario hall-b and spec files for your own halls.
• docs/tools.md: the technician bot and seeding a real NetBox from a hall.
• docs/development.md: tests, CI, releasing, source layout.

Apache-2.0. See LICENSE.