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Group Shared State

A group owns no settings of its own — it is a lens over its member hosts.
The group edit page therefore derives what it shows from the union of its
members, so an admin can see what hosts already have in common before changing
anything.

Two kinds of shared state:
1. Associations (snapins, printers, modules) — a host either has the
item or not, shown as a tri‑state checkbox: All / Some / None member
hosts have it.
2. Configuration values (Active Directory, auto‑logout, kernel/general
fields, default printer) — a host holds a value, shown as a muted
Hosts: … hint: the shared value when every member agrees, or
(varies) when they differ.

Acting on a group still pushes to all member hosts — but config fields are
no‑clobber: a blank field leaves each host's value alone, so you only
change what you intend to.

Table of contents

Associations (tri‑state)

The Snapins, Printers, and Modules tabs each render every item with a
coverage checkbox:

State Checkbox Meaning
All checked every member host has the item
Some indeterminate at least one, but not all, hosts have it
None unchecked no host has it

A n / total badge sits next to each checkbox (e.g. 5 / 15).

What "has it" means

  • Snapins, printers — a host "has it" when the association row exists. The
    printer default flag (paIsDefault) is ignored here; it's a separate
    shared value (see Default printer).
  • Modules — a host counts only when the module is enabled
    (moduleStatusByHost.msState = 1). A disabled override pulls the item out of
    All into Some. This asymmetry is deliberate (see docs/adr/0001): showing
    a module as "All hosts have it" while some have it disabled would mislead.

The badge and Has/Missing drill‑down

Clicking the badge expands an on‑demand row listing, for that one item:

  • Hosts with this (n) — the member hosts that have it, and
  • Hosts without it (n) — the member hosts that don't.

The without set is exactly what a push‑to‑all will change. The lists are
fetched per item, so large groups stay responsive.

Toggling

Clicking the checkbox acts on all member hosts:

None  --click-->  All        (add to every host)
Some  --click-->  All        (add to the hosts that lack it; modules flip
                              a disabled override back to enabled)
All   --click-->  None       (remove from every host)

So an indeterminate item resolves to All first; the destructive
remove‑from‑all only happens on a second click through the checked state.

Configuration values (shared hints)

Per‑host configuration fields show a muted hint beneath the control:

Hint Meaning
Hosts: bzImage (all) every member host holds that value
Hosts: (varies) member hosts differ
Hosts: (empty on all) none of the hosts have a value

The hint is information only — it never prefills the input.

The no‑clobber convention

Saving a group config tab pushes to all member hosts, but:

  • Blank field → leave each host's value unchanged (no clobber).
  • Literal NULL (case‑insensitive) → clear the field on every host.
  • Any other value → push that value to every host.

This is what lets you, say, set one kernel argument across a group without
wiping every other per‑host field.

Active Directory

  • Domain joining is a tri‑state select: No change (leave each host's
    join state alone), Enable on all, or Disable on all.
  • Domain / OU / username follow the no‑clobber convention above. The password's
    32‑asterisk placeholder means "unchanged".
  • Selecting Enable on all populates the blank fields from the FOG AD
    defaults (same as the host page) — only when you choose it, never just from
    existing state.
  • A Current member‑host AD state summary shows join/domain/OU/username
    uniformity above the form.

Auto‑logout

Blank by default (the global minimum is shown only as a placeholder). A blank
save leaves each host's auto‑logout alone; a number pushes to all (under five
minutes disables it). The hint reads Hosts: N min (all), (varies), or
(default on all).

General fields

Kernel, kernel arguments, init, primary disk, BIOS/EFI exit, and product key
each carry a Hosts: … hint. The kernel/args/init/disk inputs prefill from the
group's own template (the group stores these); the hint reports the
members' state independently. Push still honors the no‑clobber convention.

Default printer

The printer Default selector shows a Hosts default: <printer> (all),
(varies), or (none on all) hint. Setting a default is an explicit action
that only touches member hosts which have that printer associated.

Enforce hostname / AD‑join reboots

A tri‑state select — No change / Enable on all / Disable on all — with a
Hosts: enabled (all) / disabled (all) / (varies) hint. No change leaves each
host alone. (Stored in the hostEnforce enum('0','1') column, written as a
string — passing an int would index the enum rather than match its value.)

Out of scope

  • Force reboot is a global setting (FOG_TASK_FORCE_REBOOT) and a per‑task
    option, not per‑host configuration, so it has no group shared‑state control.