PR #72 declared the WebAuthn passwordless policy and a restructured browser-mfa
flow in the realm import. That declaration could not take effect: a
KeycloakRealmImport is a ONE-SHOT, and prod's reads Done=True / Started=False, so
every realm-level field and flow declared after the first import is inert -- in
git, applied by Flux, reported Ready, reaching the realm never. Merging it changed
nothing about how anyone logs in, and nothing anywhere said so. Same failure class
as the 2026-09-06 client-secret incident, third field over.
A SIBLING reconciler converges all three declared things every 15 minutes. It is a
sibling, not a second pass of client-secret-reconciler.yaml, so that reconciler's
allow-list -- and its guarantee that prod's real user and the media-users /
platform-admins / viewers groups are structurally unreachable -- stays literally
true. Its selftest still passes unchanged.
pass 1 webAuthnPolicyPasswordless* -- strict read-modify-write of
GET/PUT /admin/realms/homelab, readback-verified.
pass 2 webauthn-register-passwordless -- strict read-modify-write of ONE
literally-named alias; enabled, defaultAction false so enrolment stays
opt-in.
pass 3 the browser flow -- BLUE/GREEN.
PASS 3 NEVER MUTATES THE FLOW USERS ARE LOGGING IN THROUGH. Converging a
five-flow, ten-execution tree needs create-subflow, create-execution,
set-requirement and bind-config as SEPARATE untransacted calls; doing that to the
BOUND flow means a run dying between them leaves a half-built login path for every
SSO app and kubectl, and this repo has had a total SSO outage from a realm change.
So instead:
1. BUILD under a NEW, unused alias (declared alias + a hash of the desired
shape, applied to EVERY alias in the tree -- reusing browser-mfa-forms would
mean writing INTO the bound tree). A failure leaves an orphaned, unbound flow
and zero user-visible effect.
2. VERIFY by readback -- levels, ordering, authenticators, requirements, and the
conditional-OTP config CONTENTS -- before anything is bound, so the
regression that once 403'd every platform-admin is caught BEFORE it bites.
3. BIND with ONE atomic PUT setting browserFlow.
4. ROLLBACK is one write; no DELETE exists anywhere in the allow-list, so the old
flow survives as the rollback target.
The widened allow-list is made safe structurally. It cannot say "but not the bound
flow" -- its write entries are alias-parameterised -- so a second guard screens
every write against the live browserFlow's WHOLE subtree (sub-flow aliases and
execution ids) before a socket opens, FAIL-CLOSED until that binding has been
read. The create-flow endpoint carries no alias in its path, so it is screened on
its request BODY; the selftest caught that it otherwise escaped the guard.
Idempotence is load-bearing: a rebuild-and-reflip every 15 minutes would churn the
login path on a schedule. The bound flow is compared STRUCTURALLY and a match
produces zero writes and no new flow. Sub-flow and config ALIASES are deliberately
not compared -- a built flow carries a hash suffix, so comparing labels would make
it permanently unrecognisable as converged.
Single source of truth: the desired state is GENERATED from the realm import by
ci/render-keycloak-passkey-policy.py and gated with --check, so the RP ID -- baked
into every credential at enrolment and never re-keyable -- is declared once. The
pod keeps automountServiceAccountToken: false and reads a mounted ConfigMap, so no
rbac.yaml is added anywhere.
Read from Keycloak 26.0.6 source before being relied on: updateRealm
(DefaultExportImportManager 725-894) makes no getUsers/getClients/getGroups/
getRoles/getRequiredActions/getAuthenticationFlows call; it DOES read
getBrowserFlow(), which is what makes the atomic bind possible and why the policy
write pins it; the passwordless policy is applied all-or-nothing only when
RpEntityName is non-empty, with defaults substituted for omitted keys; and
updateExecutions compares rep.getPriority(), so a body omitting `priority` would
silently reshuffle the whole execution order.
Gate coverage: a new whole-repo L0 check extracts the script and runs its
--selftest (216 assertions, including a build killed at four different points each
asserting the old flow is still bound and the bound subtree was never written),
plus mutations.py (30 injected regressions, all caught) proving the selftest can
fail. An earlier iteration of this work only AUDITED the flow and left the
restructure manual; decisions/2026-10-18-keycloak-passkey-reconciler.md records
that design and why it was reconsidered.
Co-Authored-By: Claude Opus 5 (1M context) <[email protected]>
jakman85andClaude Opus 5
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