[bitnami/external-dns] Major release: drop support for multiple replicas and DaemonSet

[migruiz4]

Description of the change

External DNS does not officially support deploying multiple replicas or DaemonSet architecture, and doing so may cause issues.

References:

• support multiple replicas for reliability kubernetes-sigs/external-dns#2430
• Possible to have multiple ExternalDNS runners? kubernetes-sigs/external-dns#1089
• Upstream does not support >1 replicas nor Daemonset

Applicable issues

• fixes [bitnami/external-dns] Why bitnami chart allows to modify number of replicas for external dns when external dns does not support multiple replicas #26682

Additional information

Removed values:

• replicaCount
• useDaemonset
• revisionHistoryLimit (DaemonSet-only)
• podDisruptionBudget (Previously deprecated in favor of pdb.*)
• metrics.serviceMonitor.additionalLabels (Previously deprecated in favor of metrics.serviceMonitor.labels)

Additionally, I added the missing standard value metrics.serviceMonitor.annotations

Checklist

• Chart version bumped in Chart.yaml according to semver. This is not necessary when the changes only affect README.md files.
• Variables are documented in the values.yaml and added to the README.md using readme-generator-for-helm
• Title of the pull request follows this pattern [bitnami/<name_of_the_chart>] Descriptive title
• All commits signed off and in agreement of Developer Certificate of Origin (DCO)

[dangmai]

Hi, not sure why revisionHistoryLimit is removed in this PR? As far as I know that's used to determine how many old ReplicaSet that k8s keeps around (link), not how many replicas are currently running.
After this PR it will default to 10 and there's no way to customize it.

[bernermic]

Hi @migruiz4 and @jotamartos,
if there can be only one replica of externalDNS wouldn't it make sense to set pdb.create to false per default?
https://github.com/bitnami/charts/blob/d607a1af7dec0930f5fd730b7de2306ebc936997/bitnami/external-dns/values.yaml#L1198C5-L1203

Thanks for your good work :)

[bernermic]

I opened a PR #27467 which disables the pdb.

[DrFaust92]

please rollback the revisionHistoryLimit change 🙏 it is required and unrelated to these changes

[jetersen]

Created #27913 for the revisionHistoryLimit