## Why
Step 3 of 3 in the external-dns → in-cluster bind migration: the client-visible cutover. The `openforwarder` resolvers currently forward `k8s.syd1.au.unkin.net` to the legacy VM anycast `198.18.19.20` (a temporary measure — commit 7ee5dfb) and have NO forwarder at all for the reverse zone `200.18.198.in-addr.arpa`. Once external-dns publishes to the in-cluster `bind-externaldns` (PR 2), resolvers must read from it.
## Changes
- Repoints the `fwd-k8s-syd1-au-unkin-net` forwarder from `198.18.19.20` (legacy VM) to `198.18.200.8` (in-cluster `bind-externaldns` VIP).
- Adds `fwd-200-18-198-in-addr-arpa` forwarding `200.18.198.in-addr.arpa` → `198.18.200.8`, closing the reverse-zone gap so PTR lookups for the k8s LB range keep resolving after cutover. Modeled exactly on the existing forward-zone entries.
- Refreshes the header comment to describe the in-cluster upstream.
`kubectl kustomize apps/overlays/au-syd1/bind-internal` builds clean; both zones render with forwarder `198.18.200.8` and there is no residual `198.18.19.20`.
## Merge gate
- PR 2 (`benvin/externaldns-incluster`) merged, AND
- record parity confirmed between legacy and in-cluster for the forward zone. Spot-check (repeat for each name):
```
for n in puppetca puppet puppetdb encapi pdbmux artifactapi consul; do
echo "$n:"
dig +short @198.18.19.20 A $n.k8s.syd1.au.unkin.net
dig +short @198.18.200.8 A $n.k8s.syd1.au.unkin.net
done
# plus 2-3 PTRs in the reverse zone:
dig +short @198.18.19.20 -x 198.18.200.8
dig +short @198.18.200.8 -x 198.18.200.8
```
A/PTR answers from `198.18.200.8` must match those from `198.18.19.20` before merging.
## Verification (after merge)
```
dig +short @198.18.200.7 A puppet.k8s.syd1.au.unkin.net # resolvers VIP
dig +short @198.18.200.7 -x 198.18.200.8 # reverse via resolvers
```
Resolution through the `bind-resolvers` VIP should now answer for both the forward and reverse k8s zones.
## Rollback
Revert this PR — the `fwd-k8s-syd1-au-unkin-net` forwarder returns to `198.18.19.20` and the reverse forward is removed. The legacy VM is untouched and remains authoritative until decommission.
Reviewed-on: #288
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>
unkinben
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