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37 lines
1.7 KiB
Markdown
37 lines
1.7 KiB
Markdown
# kOps dns-controller compatibility mode
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kOps includes a dns-controller that is primarily used to bootstrap the cluster, but can also be used for provisioning DNS entries for Services and Ingress.
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ExternalDNS can be used as a drop-in replacement for dns-controller if you are running a non-gossip cluster. The flag `--compatibility kops-dns-controller` enables the dns-controller behaviour.
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## Annotations
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In kops-dns-controller compatibility mode, ExternalDNS supports two additional annotations:
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* `dns.alpha.kubernetes.io/external` which is used to define a DNS record for accessing the resource publicly (i.e. public IPs)
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* `dns.alpha.kubernetes.io/internal` which is used to define a DNS record for accessing the resource from outside the cluster but inside the cloud,
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i.e. it will typically use internal IPs for instances.
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These annotations may both be comma-separated lists of names.
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## DNS record mappings
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The DNS record mappings try to "do the right thing", but what this means is different for each resource type.
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### Pods
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For the external annotation, ExternalDNS will map a HostNetwork=true Pod to the external IPs of the Node.
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For the internal annotation, ExternalDNS will map a HostNetwork=true Pod to the internal IPs of the Node.
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ExternalDNS ignore Pods that are not HostNetwork=true
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Annotations added to Pods will always result in an A record being created.
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### Services
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* For a Service of Type=LoadBalancer, ExternalDNS looks at Status.LoadBalancer.Ingress. It will create CNAMEs to hostnames,
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and A records for IP addresses. It will do this for both internal and external names
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* For a Service of Type=NodePort, ExternalDNS will create A records for the Node's internal/external IP addresses, as appropriate. |