A container without a healthcheck counts as healthy the moment its process starts. That is how a service which came back empty passes a restore drill: the drill asks the host's health service, and the host says yes.
The image side is read from the registry rather than by pulling: the manifest names the config blob, the blob carries the HEALTHCHECK. The answer is three-valued on purpose. A mapping means the image ships a probe, an empty mapping means it definitely ships none, and None means the question could not be answered. Only the empty mapping is evidence; reading None as absent turns one network hiccup into a hundred false findings.
Probes address the GHCR mirror first and fall back upstream only for images the mirror does not carry, and a second test requires mirror plus cache to answer more often than upstream, so the fallback cannot quietly become the rule and spend the anonymous rate limit again.
Detection spans the four places a probe can come from: the services.yml declaration, a literal block in a template, a partial pulled in by include or lookup('template'), and a HEALTHCHECK in a Dockerfile the role builds its own image from. Without the last three the sweep reported nextcloud, every redis sidecar and openldap as gaps they are not.
The opposite direction gets its own lint: a declared healthcheck that no template renders is dead configuration. Fixing it surfaced that the shared resolver silently dropped every service_name call site, because it accepted only quoted literals and a role var resolves to a bare key. And the literal-protocol lint could never be suppressed on a wrapped value, since autoformat moves the marker to the value's last line while the offence is reported on its first.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
kevinveenbirkenbachandClaude Opus 5