Add Kubernetes liveness/readiness probes and middleware order validation

- Split /health into /health/live (liveness) and /health/ready (readiness)
  following Kubernetes conventions. Combined /health retained for backward
  compatibility with existing Docker HEALTHCHECK definitions.
- Add ReadyCheck and ReadyResponse models for structured readiness output.
- Add _assert_middleware_order() startup check enforcing:
  RateLimit → Csrf → CorrelationId middleware chain.
- Register CorrelationIdMiddleware, CsrfMiddleware, RateLimitMiddleware
  in create_app() with documented required order (reverse of processing).
- Add correlation.py, csrf.py, rate_limit.py middleware modules.
- Add health probe tests in test_health_probes.py.
- Update test_main.py with middleware order assertion tests.
- Update frontend useFetchData hook tests.
- Docs: update Deployment.md with Kubernetes probe config examples.
This commit is contained in:
2026-05-04 02:42:09 +02:00
parent 65fe747cba
commit eb339efcfd
13 changed files with 882 additions and 129 deletions

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@@ -78,7 +78,12 @@ During rolling deployments:
## Health Checks
The backend container includes a health check endpoint at `GET /api/v1/health` that reports application and component status:
The backend container includes **three** health check endpoints:
### Combined Health Check — `GET /api/v1/health`
Reports application and component status for Docker HEALTHCHECK and legacy
monitoring integration:
- **HTTP 200** with `{"status": "ok", ...}` — all components healthy
- **HTTP 200** with `{"status": "degraded", ...}` — some components unhealthy (e.g., database error) but fail2ban reachable
@@ -93,6 +98,59 @@ The backend container includes a health check endpoint at `GET /api/v1/health` t
| scheduler | `scheduler.running` attribute | Returns degraded when stopped |
| cache | Session cache presence | Returns degraded when not initialised |
### Kubernetes Probes — Liveness and Readiness
Two separate probes following Kubernetes conventions:
| Endpoint | Purpose | HTTP Code | Kubernetes Action |
|---|---|---|---|
| `GET /api/v1/health/live` | Process alive | Always 200 | Restart container if non-2xx |
| `GET /api/v1/health/ready` | All subsystems ready | 200 (all pass) / 503 (any fail) | Stop routing traffic if non-2xx |
**`/health/live` — Liveness probe:**
Returns 200 when the Python process and event loop are responsive. No subsystem checks are performed — this endpoint is always fast. Use for Kubernetes `livenessProbe`.
**`/health/ready` — Readiness probe:**
Verifies all critical sub-systems are reachable before routing traffic. Returns 200 only when all pass; returns 503 with a JSON body listing every failed check otherwise.
| Subsystem | Check | Timeout |
|---|---|---|
| database | Opens and closes a test connection | 2 s |
| fail2ban | Socket reachability via cached server status | N/A (instant) |
| config_dir | Config directory read access (`os.R_OK`) | 2 s |
| scheduler | `scheduler.running` attribute | N/A (instant) |
**Readiness response example (all healthy — HTTP 200):**
```json
{
"status": "ok",
"checks": [
{"name": "database", "healthy": true},
{"name": "fail2ban", "healthy": true},
{"name": "config_dir", "healthy": true},
{"name": "scheduler", "healthy": true}
],
"failed_count": 0
}
```
**Readiness response example (fail2ban offline — HTTP 503):**
```json
{
"status": "error",
"checks": [
{"name": "database", "healthy": true},
{"name": "fail2ban", "healthy": false, "message": "Socket not reachable"},
{"name": "config_dir", "healthy": true},
{"name": "scheduler", "healthy": true}
],
"failed_count": 1
}
```
**Why separate liveness and readiness?**
Liveness (`/health/live`) must be cheap — a slow or hanging liveness probe causes Kubernetes to restart a perfectly healthy container. Readiness (`/health/ready`) can afford to check sub-systems because traffic is only held back temporarily while a pod recovers.
**Docker Health Check:**
The Dockerfile includes a HEALTHCHECK that queries the endpoint. Docker interprets HTTP 503 as unhealthy and restarts the container after 3 consecutive failures (90 seconds by default).
@@ -739,9 +797,9 @@ sqlite3 /data/bangui.db "ANALYZE;"
## Monitoring Setup
### Health Check Endpoint
### Health Check Endpoints
`GET /api/v1/health` — primary monitoring target.
**Combined health check** — `GET /api/v1/health` — primary monitoring target for Docker HEALTHCHECK.
| Status | HTTP Code | Meaning |
|--------|-----------|---------|
@@ -749,6 +807,17 @@ sqlite3 /data/bangui.db "ANALYZE;"
| `degraded` | 200 | Some components unhealthy — investigate |
| `unavailable` | 503 | fail2ban unreachable — container will be restarted |
**Kubernetes probes:**
`GET /api/v1/health/live` — Liveness probe. Always returns 200 if the process is alive.
`GET /api/v1/health/ready` — Readiness probe. Returns 200 when all subsystems pass, 503 otherwise.
| Probe | URL | Success | Failure |
|-------|---|---------|---------|
| Liveness | `/api/v1/health/live` | 200 | Non-2xx → restart |
| Readiness | `/api/v1/health/ready` | 200 | Non-2xx → stop traffic |
### Structured Logging
All logs are structured (JSON via structlog). Key fields:

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@@ -1,84 +1,3 @@
### Issue #56: MEDIUM - No API Versioning or Deprecation Strategy
**Where found**:
- All backend routers register under `/api/v1/` prefix but no versioning mechanism exists
**Why this is needed**:
Breaking backend changes immediately break all frontend clients. Without a deprecation path, there is no safe way to evolve the API.
**Goal**:
Define and implement an API lifecycle policy.
**What to do**:
1. Document the versioning strategy (URL versioning is already in place; formalize it).
2. Add a `Deprecation` response header to endpoints scheduled for removal.
3. Implement a `/api/v2/` prefix for the next breaking change cycle.
4. Add a CI check that flags new breaking changes against the OpenAPI spec.
**Possible traps and issues**:
- Running two API versions simultaneously doubles maintenance surface; set a sunset date policy.
**Docs changes needed**:
- `Docs/`: create `API_VERSIONING.md` documenting the lifecycle and deprecation process.
**Doc references**:
- All router files under `backend/app/routers/`
---
### Issue #57: MEDIUM - Health Endpoint Does Not Check Subsystems
**Where found**:
- `backend/app/routers/health.py`
**Why this is needed**:
A process that is running but cannot reach the fail2ban socket, database, or config directory still returns `200 OK`. Load balancers and orchestrators treat it as healthy and route traffic to it, causing silent failures.
**Goal**:
Health endpoint reflects true readiness of all critical subsystems.
**What to do**:
1. Add a structured health check that tests: database connectivity, fail2ban socket accessibility, config directory read access, scheduler liveness.
2. Return `200` only when all checks pass; return `503` with a JSON body listing failed checks otherwise.
3. Expose a separate `/health/live` (process alive) and `/health/ready` (subsystems ready) endpoint for Kubernetes probes.
**Possible traps and issues**:
- Slow health checks (e.g., DB connect timeout) can overwhelm the endpoint under load; set short timeouts per check.
**Docs changes needed**:
- `Docs/Deployment.md`: document liveness vs readiness probe URLs.
**Doc references**:
- `backend/app/routers/health.py`
---
### Issue #58: MEDIUM - Abort Signal Not Propagated in Request Deduplication
**Where found**:
- `frontend/src/hooks/useFetchData.ts:93-113`
**Why this is needed**:
When multiple hook instances share a `requestKey`, they await a single in-flight promise. When one component unmounts and aborts its signal, the shared request continues and calls `setData()` / `onSuccess()` on the unmounted component, causing React "state update on unmounted component" warnings and memory leaks.
**Goal**:
Unmounting a component that joined a deduplicated request must not receive the result.
**What to do**:
1. In the deduplication await path, check the component's own abort signal before calling `setData()` or `onSuccess()`.
2. Wrap the deduplication subscriber list so each subscriber can individually opt out on abort.
**Possible traps and issues**:
- If all subscribers abort before the request resolves, consider whether the underlying request should also be cancelled.
**Docs changes needed**:
- `frontend/src/hooks/README.md`: document abort signal contract for deduplicated requests.
**Doc references**:
- `frontend/src/hooks/README.md`
---
### Issue #59: MEDIUM - Middleware Registration Order Not Validated at Startup
**Where found**: