The Tailscale daemon only refreshed TLS certs as a side effect of inbound
TLS handshakes or "tailscale cert" CLI calls. A node that doesn't see
inbound traffic during the renewal window silently rolls past expiry.
Add a once-per-hour background loop on LocalBackend that enumerates Serve
and Funnel HTTPS hostnames (filtered against the netmap's CertDomains so
we don't poke ACME for other nodes' service hostnames) and calls the
existing GetCertPEM path. The renewal decision (ARI window, then 2/3
expiry fallback) is unchanged; the loop just guarantees it runs.
For visibility during initial issuance or restart with a long-expired
cached cert, add a "tls-cert-pending" health Warnable that's set while
ACME is in flight and no usable cached cert exists. Async renewal of a
still-valid cert intentionally doesn't fire it.
Expose the structured health.State (with WarnableCode keys) via a new
/localapi/v0/health endpoint, registered from a new feature/health
package and conditionally pulled in via feature/condregister so it can
be linked out with ts_omit_health. tailscale cert polls that endpoint
while CertPairWithValidity blocks and prints the pending warning to
stderr, matching by WarnableCode rather than by rendered text.
Fixes#19911Fixes#19912
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
Change-Id: I144e46c40e957b2e879587decace32a523a6eade
3effed04f4