Add dnsConfig support for GitLab pod specs

Courtney Wilburnrequested to merge
add-dnsconfig-support into master

What does this MR do?

Adds opt-in pod-level dnsConfig support across all GitLab-owned components, resolving #6277 (closed).

Users can set a cluster-wide default via global.dnsConfig and override it per component. The most common use case is lowering ndots (e.g. from the Kubernetes default of 5 to 2) to cut NXDOMAIN responses and DNS latency when resolving fully-qualified external hostnames such as object-storage endpoints.

global:
  dnsConfig:
    options:
      - name: ndots
        value: "2"

gitlab:
  sidekiq:               # per-component override
    dnsConfig:
      options:
        - name: ndots
          value: "3"

Implementation

  • New shared helper gitlab.dnsConfig (templates/_application.tpl) using the same local-overrides-global pattern as gitlab.nodeSelector / gitlab.tolerations.
  • global.dnsConfig: {} default plus per-component dnsConfig: {} in each sub-chart's values.yaml.
  • Applied to every GitLab-owned pod spec: webservice, sidekiq, gitaly, praefect, gitlab-shell, kas, toolbox (+ backup/reindex CronJobs), migrations, registry (+ migrations Job), gitlab-exporter, gitlab-pages, mailroom, geo-logcursor, certmanager-issuer Job, shared-secrets Jobs, and the upgrade-check Job.
  • Backward compatible / opt-in: when unset, no dnsConfig is emitted and Kubernetes defaults are preserved.
  • Bumps certmanager-issuer chart version 0.5.0 → 0.5.1 (Job templates are immutable; the version feeds the generated Job-name hash) per https://docs.gitlab.com/charts/charts/globals/#jobs
  • Docs: new "DNS Configuration" section in doc/charts/globals.md.

Related issues

Closes #6277 (closed)

Author checklist

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Required

For anything in this list which will not be completed, please provide a reason in the MR discussion.

  • Merge Request Title and Description are up to date, accurate, and descriptive.
  • MR targeting the appropriate branch.
  • MR has a green pipeline.
  • Documentation created/updated.
  • Tests added/updated, and test plan for scenarios not covered by automated tests. + e2e validation notes at !5133 (comment 3584528517)
  • [-] Equivalent MR/issue for omnibus-gitlab opened. - n/a

Reviewers checklist

Edited by Nailia Iskhakova

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