Readiness checks

Each host reports what its node agent actually found on the machine. The checks are on the host’s page under Admin ▸ Fleet and in step 3 of the first-run wizard. Blocking and overrides: Hosts and GPUs.

Part of a rootless Docker host's readiness card: a home-ownership warning, media reachability from a real session, the experimental engine profile, and the console checks.

Status	Meaning
Pass	Fine.
Warn	Works, with a note. Never blocks.
Fail	Broken. Blocks launches only when marked Blocks launches.
Unknown	Not checked yet, or inconclusive. Never blocks.
Skipped	Not applicable, or an optional diagnostic not enabled (it names the setting).

Prepare the host means the host steps for your engine: Docker, Podman or rootless. Each step is safe to repeat.

Container engine

Check	Meaning and fix
runtime_endpoint	The Docker or Podman socket answers. Failing blocks the host. If DOCKER_HOST and CONTAINER_HOST name different engines, unset one.
runtime_engine	The engine and its engine profile. Experimental or unsupported profiles warn only. Podman older than 5.1 reads as unsupported: upgrade it, or updates will fail.
runtime_cdi	How NVIDIA GPUs reach containers (CDI or --gpus). If neither works, the host is blocked: follow NVIDIA setup for your engine, then restart it.
runtime_cdi_gpu<N>	The same, per NVIDIA GPU on a mixed-vendor host. Blocks only that GPU.
engine_restart_on_boot	Whether the engine brought Quasar back at the last reboot. Passes once a reboot proves it; unknown until the host first reboots after install. Fails if the node agent came back much later. Rootful Docker skips it. The fix is host preparation: podman-restart.service (Podman), and lingering plus the user’s engine service (rootless).
engine_healthchecks	Podman only. Health checks need a systemd session, or installs time out. Rootless: enable lingering for the quasar account and restart the Podman service. Rootful: use the systemd cgroup manager.

Input

Check	Meaning and fix
uinput	The agent can open /dev/uinput for writing. Rootless: install the device rules.
input_probe	The agent creates a virtual device and opens it. Failing blocks the host. Rootless: install the device rules. Rootful: check /dev/uinput and /dev/input reach the agent.

Storage

Check	Meaning and fix
homes_root_writable	A test home can be written. Failing blocks launches that need a home. On rootless Docker it warns: session files are owned by a subordinate ID. Sessions still work; use rootless Podman if you want files owned by the Quasar account. Never re-own existing homes recursively (Moving to rootless).
homes_free_space	Warns below 5 GiB free (QUASAR_HOMES_FREE_SPACE_FLOOR_GIB); fails when full.

Network

media_reachability comes from real sessions from another machine, and never blocks.

• Unknown until a remote browser has tried a session.
• Pass once a remote browser’s media reached the host (that browser’s path only).
• Fail when a remote browser’s connection failed with no checks arriving. Open the media port range: Ports and endpoints.

GPU fault messages

xid_visibility: whether the agent can read GPU fault messages from the kernel log for session traces. Optional and off by default: see GPU fault messages in session traces, or read dmesg yourself.

Console mode

The console checks (console_card, console_input, console_sound, console_terminal, console_udev, console_ddc) are skipped while console mode is off, and never block streaming. See Console mode. Most fixes end the same way: run host preparation with --console, then turn console mode off and on so the agent is re-created with the devices.

Failure	Fix
A card, input, sound or terminal node can’t be opened	Install the console device rules (prepare-host.sh --console). Replug an input device it missed.
Another program holds the display	Stop the desktop or login screen on that output, or pick another. On an NVIDIA or rootless host a streamed game can hold it too: end that session (which hosts).
A listed input device is not on this host	Plug it in, or edit Input devices. Numbers can change when devices are replugged.
No sound device	Check the host’s sound driver is loaded. Without one the console desktop has no sound.
tty8 is another session’s terminal	Stop the login prompt on tty8 (host preparation masks getty@tty8).
No udev data on the host	The host must run systemd-udevd.
console_udev unknown	The agent predates the check. Turn console mode off and on.
ddcutil missing, or no i2c bus for a connector	Every connected display counts as on. Check /dev/i2c-* exists (the console device rules grant it on rootless) and a monitor is connected. On rootless, a /dev/i2c-N that is a plain file rather than a device is skipped and named in the recovery actor’s log: remove it, then toggle console mode off and on.

Owner conflict

owner_conflict: a Quasar-like container not created by this install (usually an old Compose stack) is in the way. Updates to that machine are blocked until you remove it and whatever re-creates it.