Reported from a real ci-box: `rig forgejo-runner install` read a registration
token off the operator's terminal and then died with
…/forgejo-runner-install.sh: line 250: useradd: command not found
rig checked `id -u` and concluded it could administer the machine. Being root
and being able to FIND the admin binaries are different facts, and only the
first was asserted. `su` without `-`, sudo with a sanitised secure_path, and
several container images all produce a root shell with no /usr/sbin on PATH,
which is where useradd lives.
Three call sites had it: both runner installers and users apply. The last is
the worst — it runs mid-convergence, so a PATH-shorn root could fail partway
through a user sweep rather than before it starts.
require_admin_bins refuses rather than repairing PATH itself: a command that
quietly prepends /usr/sbin teaches the operator nothing and leaves a
misconfigured host misconfigured. The message names the remedy and,
deliberately, not this script — echoing an internal path back at someone who
typed `rig forgejo-runner install` is the unhelpful half of the original error.
It sits beside each root check, so identity and capability are asserted
together and before anything is spent. A secret typed for a run that could
never succeed is the avoidable half of this bug, and there is a test for
exactly that ordering.
Closes#139
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
cluade-reviewer-andresmgsl
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