First egress rule in matrix, authentik and monitoring. It allows DNS, the cluster
ranges and the whole internet, and denies only 169.254.0.0/16 - link-local, where
Hetzner serves instance metadata unauthenticated to any pod.
Deliberately narrow. The textbook cut, 0.0.0.0/0 except RFC1918, would have severed
two things here, both over 10.0.0.3 on the private Hetzner network: Alloy writes
metrics and logs there, and the TURN rotation reaches Gitea through a hostAlias to
that address. Private ranges therefore stay open.
The payoff is modest and should be stated as such: measured from a pod, the service
answers with instance-id, hostname, region, MAC and network config, while userdata
and public-keys are empty. No credentials are exposed here, unlike the AWS case this
hardening usually targets. It costs nothing though, and it closes the class.
Two preconditions checked rather than assumed, because both are the usual way this
breaks: kube-system carries kubernetes.io/metadata.name so the DNS rule actually
matches, and the cluster is IPv4-only so 0.0.0.0/0 really does cover everything.
Rollback is deleting the one policy per namespace.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Closes issues #6 and #15 (treated jointly, per combined analysis in their
comments). Two CronJobs, one per namespace, each pushing to its own Borg
repo on the newly booked Storage Box (u641795.your-storagebox.de:23, BX11
1TB) with its own repo passphrase - a leaked passphrase for one doesn't
expose the other:
- matrix: synapse-backup dumps the synapse + matrixauthenticationservice
DBs (shared postgres, existing chart-generated POSTGRES_ADMIN_PASSWORD)
and the Synapse media_store PVC (read-only mount)
- authentik: authentik-backup dumps the authentik DB (existing
authentik-credentials pg-password)
Custom image (rohana.axion1337.de/sorb/axion-backup:v1, postgres:17-alpine
+ borgbackup + openssh-client - matches the live Postgres major version
exactly, unlike Alpine's stock postgresql16-client) pushed as a public
package, same pattern as the existing threadnet-web image (no
imagePullSecret needed).
SSH host key pinned via known_hosts ConfigMap (captured via ssh-keyscan
ahead of time) rather than trusting on first connect in an unattended job.
Retention: 7 daily / 4 weekly / 6 monthly via borg prune. Schedule: 03:00
and 03:15, offset to avoid resource contention.
NetworkPolicy: added each backup job's pod as an allowed source to its
namespace's existing postgres ingress rule (matrix's allow-ingress-postgres,
authentik's allow-ingress-authentik-postgresql from #37). Egress already
unrestricted in both namespaces, so no change needed for the outbound SSH
connection to the Storage Box.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Closes issue #37. The Bitnami postgresql subchart's auto-generated
NetworkPolicy restricted the port (5432) but not the source - any pod in
any namespace could reach it, since additive NetworkPolicy rules can't
restrict an existing permissive one, only the chart itself controls it
(hence not touched during the original #10 rollout).
Disabled via postgresql.primary.networkPolicy.enabled: false and replaced
with a scoped policy allowing only authentik-server and authentik-worker
(same namespace) on 5432, matching the pattern already used for the
matrix namespace's postgres access. No metrics exporter is enabled for
this instance, so no monitoring-namespace rule is needed.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Caused a live 502 immediately after deploy: the rule allowed 80/443
(the Service's external ports), but NetworkPolicy filters on the pod's
actual container port after kube-proxy's DNAT - authentik-server's
Service maps 80->9000 and 443->9443. Confirmed root cause by suspending
Flux reconciliation (it was silently re-applying my manual test
deletions) and testing with the policies truly absent.
Ingress-only default-deny (egress untouched) plus explicit allows:
Traefik (kube-system) + MAS (matrix ns) -> authentik-server on 80/443,
and Traefik -> cert-manager's ACME HTTP-01 solver pods on 8089.
authentik-postgresql already has its own Bitnami-chart-managed policy,
left alone. Part of issue #10.
Thore CimbalandClaude Opus 5