Merge pull request #57403 from wwwtyro/rye/deprecated-dns-ip-handling

Automatic merge from submit-queue (batch tested with PRs 57400, 57403, 57303). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Use old dns-ip mechanism with older cdk-addons.

**What this PR does / why we need it**: Use old dns-ip mechanism with older cdk-addons.

**Release note**:
```release-note
Use old dns-ip mechanism with older cdk-addons.
```

cluster/juju/layers/kubernetes-master/reactive/kubernetes_master.py

@@ -601,6 +601,7 @@ def configure_cdk_addons():
     dnsEnabled = str(hookenv.config('enable-kube-dns')).lower()
     args = [
         'arch=' + arch(),
+        'dns-ip=' + get_deprecated_dns_ip(),
         'dns-domain=' + hookenv.config('dns_domain'),
         'enable-dashboard=' + dbEnabled,
         'enable-kube-dns=' + dnsEnabled
@@ -976,6 +977,14 @@ def get_dns_ip():
     return svc['spec']['clusterIP']
 
 
+def get_deprecated_dns_ip():
+    '''We previously hardcoded the dns ip. This function returns the old
+    hardcoded value for use with older versions of cdk_addons.'''
+    interface = ipaddress.IPv4Interface(service_cidr())
+    ip = interface.network.network_address + 10
+    return ip.exploded
+
+
 def get_kubernetes_service_ip():
     '''Get the IP address for the kubernetes service based on the cidr.'''
     interface = ipaddress.IPv4Interface(service_cidr())