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kevinveenbirkenbach
49f2dd516b
Ansible's marker behaviour replaces an undefined name with the literal
'<< error N - NAME is undefined >>' instead of raising, and it is
inherited ambiently from whatever task is rendering, so code calling
templar.template(fail_on_undefined=True) gets that string back rather
than an exception.
_render_with_templar then returns it, get_merged_applications memoises
it unconditionally under a key that fingerprints only applications,
users and two domains, and hands the same object back without a
deepcopy. The first caller in the process therefore freezes the value
for every later one: a lookup from another role renders a role's addon
config without that role's vars, and the role itself is served the
poisoned result afterwards even though its own read happens in the right
scope.
It reached a running Nextcloud as the stored Collabora WOPI URL. A
configuration key set to an error message is worse than a missing one,
because the application stores it and reports itself configured.
The check sits at the end of the one function every merge render passes
through, so applications, users and domains are covered, and it runs
before any caller can memoise. The path is carried down while
descending, so the message names the offending key rather than the
payload. The pattern requires the ordinal and the dash so prose about
errors does not trip it.
2678090934 made the same choice for the lookup layer; this is the cache
layer.
This raises where the code used to continue. That is the point - a value
nobody can act on should stop a deploy rather than configure an
application - but the blast radius is only measured by the next deploy.