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Adds nodelocaldns_additional_configs to facilitate additional CoreDNS config options #11657

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Nov 8, 2024
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Adds nodelocaldns_additional_configs to facilitate additional CoreDNS config options #11657

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8 changes: 8 additions & 0 deletions docs/advanced/dns-stack.md
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Original file line number Diff line number Diff line change
Expand Up @@ -64,6 +64,10 @@ Custom options to be added to the kubernetes coredns plugin.

Extra domains to be forwarded to the kubernetes coredns plugin.

### coredns_additional_configs

Extra configuration to be added to CoreDNS configuration

### coredns_rewrite_block

[Rewrite](https://coredns.io/plugins/rewrite/) plugin block to perform internal message rewriting.
Expand Down Expand Up @@ -290,6 +294,10 @@ nodelocaldns_external_zones:

See [dns_etchosts](#dns_etchosts-coredns) above.

### nodelocaldns_additional_configs

Extra configuration to be added to CoreDNS configuration

### Nodelocal DNS HA

Under some circumstances the single POD nodelocaldns implementation may not be able to be replaced soon enough and a cluster upgrade or a nodelocaldns upgrade can cause DNS requests to time out for short intervals. If for any reason your applications cannot tolerate this behavior you can enable a redundant nodelocal DNS pod on each node:
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5 changes: 5 additions & 0 deletions roles/kubernetes-apps/ansible/defaults/main.yml
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Expand Up @@ -55,6 +55,11 @@ nodelocaldns_ds_nodeselector: "kubernetes.io/os: linux"
nodelocaldns_prometheus_port: 9253
nodelocaldns_secondary_prometheus_port: 9255

# nodelocaldns_additional_configs adds any extra configuration to coredns
# nodelocaldns_additional_configs: |
# whoami
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See:https://github.com/kubernetes/kubernetes/blob/d9b95ea94f41b942440adbdfdbe35fb78a2ed6f7/cluster/addons/dns/nodelocaldns/nodelocaldns.yaml#L58

By default, we don't need these configs indeed, Can you explain why we need it? thanks!

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@0x4c6565 0x4c6565 Nov 7, 2024 •
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For my particular use case, I wish to use the template plugin to respond to a query, so that this can be rewritten to a k8s service address via CNAME. I'm unable to utilise the existing coredns_additional_configs variable for this as this isn't used in the nodelocal dns config template, only in the coredns config template, and queries for non-k8s service addresses are passed directly to upstream from nodelocal dns

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I see, thanks for the explanation.

# local

# Limits for dns-autoscaler
dns_autoscaler_cpu_requests: 20m
dns_autoscaler_memory_requests: 10Mi
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6 changes: 6 additions & 0 deletions roles/kubernetes-apps/ansible/templates/nodelocaldns-config.yml.j2
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Expand Up @@ -75,6 +75,9 @@ data:
prometheus {% if nodelocaldns_bind_metrics_host_ip %}{$MY_HOST_IP}{% endif %}:{{ nodelocaldns_prometheus_port }}
}
.:53 {
{% if nodelocaldns_additional_configs is defined %}
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Should in-addr.arpa:53 and ip6.arpa:53 require these configs if we need these configs?

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It depends on the intended use of this variable I suppose. I kept this consistent with coredns_additional_configs:

kubespray/roles/kubernetes-apps/ansible/templates/coredns-config.yml.j2

Lines 37 to 40 in d23753e

.:53 {
{% if coredns_additional_configs is defined %}
{{ coredns_additional_configs | indent(width=8, first=False) }}
{% endif %}

{{ nodelocaldns_additional_configs | indent(width=8, first=False) }}
{% endif %}
errors
cache 30
reload
Expand Down Expand Up @@ -157,6 +160,9 @@ data:
prometheus {% if nodelocaldns_bind_metrics_host_ip %}{$MY_HOST_IP}{% endif %}:{{ nodelocaldns_secondary_prometheus_port }}
}
.:53 {
{% if nodelocaldns_additional_configs is defined %}
{{ nodelocaldns_additional_configs | indent(width=8, first=False) }}
{% endif %}
errors
cache 30
reload
Expand Down