kube/bind/README.md

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# Bind namespace
The Bind secondary servers and `external-dns` service pods are running in this namespace.
The `external-dns` pods are used to declaratively update DNS records on the
[Bind primary](https://git.k-space.ee/k-space/ansible/src/branch/main/authoritative-nameserver.yaml).
The Bind primary `ns1.k-space.ee` resides outside Kubernetes at `193.40.103.2` and
it's internally reachable via `172.20.0.2`.
Bind secondaries perform AXFR (zone transfer) from `ns1.k-space.ee` using
shared secret autentication.
The primary triggers notification events to `172.20.53.{1..3}`
which are internally exposed IP-s of the secondaries.
Bind secondaries are hosted inside Kubernetes, load balanced behind `62.65.250.2` and
under normal circumstances managed by [ArgoCD](https://argocd.k-space.ee/applications/argocd/bind).
Note that [cert-manager](https://git.k-space.ee/k-space/kube/src/branch/master/cert-manager/issuer.yml) also performs DNS updates on the Bind primary.
# For user
`Ingresses` and `DNSEndpoint` resources under `k-space.ee`, `kspace.ee`, `k6.ee`
domains are picked up automatically by `external-dns` and updated on the Bind primary.
To find usage examples in this repository use
`grep -r -A25 "^kind: Ingress" .` and
`grep -R -r -A100 "^kind: DNSEndpoint" .`
# For administrator
To configure TSIG secrets:
```
kubectl create secret generic -n bind bind-readonly-secret \
--from-file=readonly.key
kubectl create secret generic -n bind bind-readwrite-secret \
--from-file=readwrite.key
kubectl create secret generic -n bind external-dns
kubectl -n bind delete secret tsig-secret
kubectl -n bind create secret generic tsig-secret \
--from-literal=TSIG_SECRET=$(cat readwrite.key | grep secret | cut -d '"' -f 2)
kubectl -n cert-manager delete secret tsig-secret
kubectl -n cert-manager create secret generic tsig-secret \
--from-literal=TSIG_SECRET=$(cat readwrite.key | grep secret | cut -d '"' -f 2)
```
# Serving additional zones
## Bind primary configuration
To serve additional domains from this Bind setup add following
section to `named.conf.local` on primary `ns1.k-space.ee`:
```
key "foobar" {
algorithm hmac-sha512;
secret "...";
};
zone "foobar.com" {
type master;
file "/var/lib/bind/db.foobar.com";
allow-update { !rejected; key foobar; };
allow-transfer { !rejected; key readonly; key foobar; };
notify explicit; also-notify { 172.20.53.1; 172.20.53.2; 172.20.53.3; };
};
```
Initiate empty zonefile in `/var/lib/bind/db.foobar.com` on the primary `ns1.k-space.ee`:
```
foobar.com IN SOA ns1.foobar.com. hostmaster.foobar.com. (1 300 300 2592000 300)
NS ns1.foobar.com.
NS ns2.foobar.com.
ns1.foobar.com. A 193.40.103.2
ns2.foobar.com. A 62.65.250.2
```
Reload Bind config:
```
named-checkconf
systemctl reload bind9
```
## Bind secondary config
Add section to `bind-secondary-config-local` under key `named.conf.local`:
```
zone "foobar.com" { type slave; masters { 172.20.0.2 key readonly; }; };
```
And restart secondaries:
```
kubectl rollout restart -n bind statefulset/bind-secondary
```
## Registrar config
At your DNS registrar point your glue records to:
```
foobar.com. NS ns1.foobar.com.
foobar.com. NS ns2.foobar.com.
ns1.foobar.com. A 193.40.103.2
ns2.foobar.com. A 62.65.250.2
```
## Updating DNS records
With the configured TSIG key `foobar` you can now:
* Obtain Let's Encrypt certificates with DNS challenge.
Inside Kubernetes use `cert-manager` with RFC2136 provider.
* Update DNS records.
Inside Kubernetes use `external-dns` with RFC2136 provider.