* feat(annotations): add custom annotation prefix support for split horizon DNS
Add --annotation-prefix flag to allow customizing the annotation prefix
used by external-dns. This enables split horizon DNS scenarios where
multiple instances process different sets of annotations from the same
Kubernetes resources.
Changes:
- Add AnnotationPrefix field to Config with validation
- Convert annotation constants to variables that can be reconfigured
- Add SetAnnotationPrefix() function to rebuild annotation keys
- Integrate annotation prefix setting in controller startup
- Update Helm chart with annotationPrefix value
- Add comprehensive split horizon DNS documentation
- Update FAQ with annotation prefix examples
This maintains full backward compatibility - the default prefix remains
"external-dns.alpha.kubernetes.io/".
Co-Authored-By: Claude <noreply@anthropic.com>
* docs(advanced): fix markdown formatting in split-horizon guide
Add blank lines before code blocks to improve markdown rendering
and comply with markdownlint rules.
Co-Authored-By: Claude <noreply@anthropic.com>
* docs(advanced): fix markdown formatting in split-horizon guide
Co-Authored-By: Claude <noreply@anthropic.com>
* docs(charts): regenerate Helm chart documentation
Co-Authored-By: Claude <noreply@anthropic.com>
* test: add AnnotationPrefix field to test configs
Add missing AnnotationPrefix field to minimalConfig and overriddenConfig
test configurations to match the new default value set in NewConfig().
Co-Authored-By: Claude <noreply@anthropic.com>
* test(charts): update error pattern in json-schema test
Update expected error message pattern to match current Helm validation
output format.
Co-Authored-By: Claude <noreply@anthropic.com>
* refactor(annotations): remove init() for explicit initialization
- Remove init() function from annotations package
- Add explicit SetAnnotationPrefix() call in controller/execute.go
- Remove annotation key aliases from source/source.go
- Replace all alias usages with annotations.* references (348 changes in 28 files)
- Add TestMain to existing test files (service_test.go, cloudflare_test.go)
This change makes annotation initialization explicit and predictable,
avoiding hidden global state initialization at import time.
Co-Authored-By: Claude <noreply@anthropic.com>
* docs: update changelog and mkdocs to include annotationPrefix and split horizon DNS
Signed-off-by: Aleksei Sviridkin <f@lex.la>
* docs(split-horizon): fix linting
Signed-off-by: Aleksei Sviridkin <f@lex.la>
* refactor(annotations): replace hardcoded annotation prefix with constant
Replace all hardcoded "external-dns.alpha.kubernetes.io/" strings
with annotations.DefaultAnnotationPrefix constant to establish
a single source of truth.
Changes:
- Add DefaultAnnotationPrefix constant in source/annotations/annotations.go
- Replace hardcoded string in controller/execute.go with constant reference
- Replace hardcoded strings in pkg/apis/externaldns/types.go (2 occurrences)
- Add helm unit tests for annotationPrefix value
This eliminates string duplication and makes future changes easier.
Co-Authored-By: Claude <noreply@anthropic.com>
---------
Signed-off-by: Aleksei Sviridkin <f@lex.la>
Co-authored-by: Claude <noreply@anthropic.com>
* Add annotation filter to Ambassador Host Source
This change makes the Ambassador Host source respect the External-DNS annotationFilter allowing for an Ambassador Host resource to specify what External-DNS deployment to use when there are multiple External-DNS deployments within the same cluster. Before this change if you had two External-DNS deployments within the cluster and used the Ambassador Host source the first External-DNS to process the resource will create the record and not the one that was specified in the filter annotation.
I added the `filterByAnnotations` function so that it matched the same way the other sources have implemented annotation filtering. I didn't add the controller check only because I wanted to keep this change to implementing the annotationFilter.
Example: Create two External-DNS deployments 1 public and 1 private and set the Ambassador Host to use the public External-DNS using the annotation filter.
```
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: external-dns-private
spec:
strategy:
type: Recreate
selector:
matchLabels:
app: external-dns-private
template:
metadata:
labels:
app: external-dns-private
annotations:
iam.amazonaws.com/role: {ARN} # AWS ARN role
spec:
serviceAccountName: external-dns
containers:
- name: external-dns
image: k8s.gcr.io/external-dns/external-dns:latest
args:
- --source=ambassador-host
- --domain-filter=example.net # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
- --provider=aws
- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
- --aws-zone-type=private # only look at public hosted zones (valid values are public, private or no value for both)
- --registry=txt
- --txt-owner-id= {Hosted Zone ID} # Insert Route53 Hosted Zone ID here
- --annotation-filter=kubernetes.io/ingress.class in (private)
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: external-dns-public
spec:
strategy:
type: Recreate
selector:
matchLabels:
app: external-dns-public
template:
metadata:
labels:
app: external-dns-public
annotations:
iam.amazonaws.com/role: {ARN} # AWS ARN role
spec:
serviceAccountName: external-dns
containers:
- name: external-dns
image: k8s.gcr.io/external-dns/external-dns:latest
args:
- --source=ambassador-host
- --domain-filter=example.net # will make ExternalDNS see only the hosted zones matching provided domain, omit to process all available hosted zones
- --provider=aws
- --policy=upsert-only # would prevent ExternalDNS from deleting any records, omit to enable full synchronization
- --aws-zone-type= # only look at public hosted zones (valid values are public, private or no value for both)
- --registry=txt
- --txt-owner-id= {Hosted Zone ID} # Insert Route53 Hosted Zone ID here
- --annotation-filter=kubernetes.io/ingress.class in (public)
---
apiVersion: getambassador.io/v3alpha1
kind: Host
metadata:
name: your-hostname
annotations:
external-dns.ambassador-service: emissary-ingress/emissary
kubernetes.io/ingress.class: public
spec:
acmeProvider:
authority: none
hostname: your-hostname.example.com
```
Fixeskubernetes-sigs/external-dns#2632
* Add Label filltering for Ambassador Host source
Currently the `--label-filter` flag can only be used to filter CRDs, Ingress, Service and Openshift Route objects which match the label selector passed through that flag. This change extends the functionality to the Ambassador Host type object.
When the flag is not specified the default value is `labels.Everything()` which is an empty string, the same as before. An annotation based filter is inefficient because the filtering has to be done in the controller instead of the API server like with label filtering. The Annotation based filtering has been left in for legacy reasons so the Ambassador Host source can be used inconjunction with the other sources that don't yet support label filltering.
It is possible to use label based filltering with annotation based filltering so you can initially filter by label then filter the returned hosts by annotation. This is not recomended
* Update Ambassador Host source docs
Add that the Ambassador Host source now supports both annotation and label filltering.
Ambassador can be configured with `Host` resources (based on the
`Host` CRD) for defining the external DNS host name.
This code adds a new source, `ambassador-host`, that looks for the
`ambassador/ambassador` Service and and uses the `hostname` from the
`Host` resource.
Signed-off-by: Alvaro Saurin <alvaro.saurin@gmail.com>
Signed-off-by: Flynn <flynn@datawire.io>
