key-cape/workplans/KEY-WP-0025-runtime-lifecycle-and-readiness.md

---
id: KEY-WP-0025
type: workplan
title: "Give the runtime real readiness, graceful shutdown and stated operational limits"
domain: infotech
repo: key-cape
status: finished
owner: claude
topic_slug: runtime-lifecycle-and-readiness
created: "2026-09-08"
updated: "2026-09-08"
---

Closes gap G08. `/healthz` returned a constant without probing anything, the
server called `ListenAndServe` with no signal handling, and the operational
limits of in-memory state, startup-loaded keys and local-only logout were spread
across code comments rather than stated anywhere an operator would look.

G08 explicitly does not require shared storage or refresh tokens. The work is
therefore to make readiness real, make restarts survivable for in-flight
requests, and write the limits down honestly.

## Separate readiness from liveness

```task
id: KEY-WP-0025-T01
status: done
priority: medium
```

Added `internal/server/readiness` and a `/readyz` endpoint probing LLDAP,
Authelia and privacyIDEA. `/healthz` stays liveness and deliberately probes
nothing: wiring liveness to dependency health means an orchestrator restarts
KeyCape when a dependency blinks, and since a restart also discards every
in-flight login, the reaction is worse than the condition.

Design decisions worth keeping:

- **LLDAP is probed with a bind, not a dial.** A rotated or revoked service
  password leaves the port open and every lookup failing — precisely the state
  readiness exists to catch, and precisely what a TCP dial would miss.
- **The body names the failing check but never the reason.** The endpoint is
  unauthenticated, and upstream error text carries hostnames and sometimes
  credentials-in-URLs. Detail goes to the log. A test asserts a probe error
  containing a credentialed URL does not reach the response.
- **Results are cached for 2s.** Not an optimisation: without it, anyone able to
  reach an unauthenticated endpoint could drive one upstream request per
  dependency per call.
- **Probes run concurrently, each bounded at 3s**, so readiness costs the slowest
  probe rather than their sum, and a hung dependency makes the endpoint answer
  rather than hang alongside it.

## Shut down without dropping requests

```task
id: KEY-WP-0025-T02
status: done
priority: medium
```

`SIGTERM`/`SIGINT` now drain in-flight requests for up to 15 seconds. The grace
period sits under the 30s read/write timeouts so a stuck request cannot outlive
the window an orchestrator allows before `SIGKILL`.

In-memory login state is deliberately not preserved: a browser mid-login must
start again after a restart. That is a property of the single-replica topology,
documented rather than papered over.

## State the operational limits

```task
id: KEY-WP-0025-T03
status: done
priority: medium
```

`docs/operations.md` states the supported topology — exactly one replica, because
authorization codes, login sessions and handoffs are process-local and no sticky
configuration makes a second replica safe — and the consequences: restarts drop
in-flight logins while issued tokens keep working, and rolling deploys have a
window where new logins fail.

It also records three limits that are easy to get wrong in operation:

- the key ID is the constant `key-1`, so rotating the key without changing it can
  leave consumers caching JWKS by `kid` rejecting freshly issued tokens;
- removing a client registration does not revoke its issued tokens, since there
  is no revocation or introspection endpoint — they stay valid until expiry;
- `/logout` clears the local session only, not the Authelia session or any token.

No throughput or resource figures are given: nothing here benchmarks KeyCape, so
any number would be invented.

## Verify in the running server

```task
id: KEY-WP-0025-T04
status: done
priority: medium
```

Checked against the built executable rather than the handlers, following the
lesson from KEY-WP-0023:

- with every dependency down, `/readyz` returns 503 naming all three as failed
  while `/healthz` still returns 200 — the split doing its job;
- starting LLDAP flips its check to `ok` while the others stay failed, so the
  probes are measuring what they claim;
- 40 requests issued across a `SIGTERM` all returned 200, and the log shows the
  signal handled and shutdown completed.

Seven unit tests cover the reporter, including the disclosure, caching, timeout
and concurrency properties above.