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* BREAKING CHANGE: Improve default targets management * fix: Remove old test case * fix: Test confirming legacy mode allows empty CRD targets * fix: Remove comments * fix: Move flag definition closer to detault-targets * fix: Initial merge adaptation * fix: Improved legacy needs a chance to work with empty CRD list * fix: Code coverage and dead code * fix: Simpler Endpoints logic * fix: Flag description * feat: Add tutorial * fix: Improve linting * fix: Improve linting * fix: Import linting
72 lines
3.0 KiB
Markdown
72 lines
3.0 KiB
Markdown
# Using CRD Source for DNS Records
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This tutorial describes how to use the CRD source with ExternalDNS to manage DNS records. The CRD source allows you to define your desired DNS records declaratively using `DNSEndpoint` custom resources.
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## Default Targets and CRD Targets
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ExternalDNS has a `--default-targets` flag that can be used to specify a default set of targets for all created DNS records. The behavior of how these default targets interact with targets specified in a `DNSEndpoint` CRD has been refined.
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### New Behavior (default)
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By default, ExternalDNS now has the following behavior:
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- If a `DNSEndpoint` resource has targets specified in its `spec.endpoints[].targets` field, these targets will be used for the DNS record, **overriding** any targets specified via the `--default-targets` flag.
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- If a `DNSEndpoint` resource has an **empty** `targets` field, the targets from the `--default-targets` flag will be used. This allows for creating records that point to default load balancers or IPs without explicitly listing them in every `DNSEndpoint` resource.
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### Legacy Behavior (`--force-default-targets`)
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To maintain backward compatibility and support certain migration scenarios, the `--force-default-targets` flag is available.
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- When `--force-default-targets` is used, ExternalDNS will **always** use the targets from `--default-targets`, regardless of whether the `DNSEndpoint` resource has targets specified or not.
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This flag allows for a smooth migration path to the new behavior. It allow keeping old CRD resources, allows to start removing targets from one by one resource and then remove the flag.
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## Examples
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Let's look at how this works in practice. Assume ExternalDNS is running with `--default-targets=1.2.3.4`.
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### DNSEndpoint with Targets
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Here is a `DNSEndpoint` with a target specified.
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```yaml
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---
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apiVersion: externaldns.k8s.io/v1alpha1
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kind: DNSEndpoint
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metadata:
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name: targets
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namespace: default
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spec:
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endpoints:
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- dnsName: smoke-t.example.com
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recordTTL: 300
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recordType: CNAME
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targets:
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- placeholder
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```
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- **Without `--force-default-targets` (New Behavior):** A CNAME record for `smoke-t.example.com` will be created pointing to `placeholder`.
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- **With `--force-default-targets` (Legacy Behavior):** A CNAME record for `smoke-t.example.com` will be created pointing to `1.2.3.4`. The `placeholder` target will be ignored.
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### DNSEndpoint with Empty/No Targets
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Here is a `DNSEndpoint` without any targets specified.
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```yaml
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---
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apiVersion: externaldns.k8s.io/v1alpha1
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kind: DNSEndpoint
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metadata:
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name: no-targets
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namespace: default
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spec:
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endpoints:
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- dnsName: smoke-nt.example.com
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recordTTL: 300
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recordType: CNAME
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```
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- **Without `--force-default-targets` (New Behavior):** A CNAME record for `smoke-nt.example.com` will be created pointing to `1.2.3.4`.
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- **With `--force-default-targets` (Legacy Behavior):** A CNAME record for `smoke-nt.example.com` will be created pointing to `1.2.3.4`.
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`--force-default-targets` allows migration path to clean CRD resources.
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