Thanos 127/convert to passthrough

General MR

Umbrella branch

thanos-127/passthrough-conversion

Summary

Converts Thanos to passthrough pattern. Due to the Bitnami tax the chart will have to be manually vendored for each update, those changes are reflected in the documentation for this package as well as the implementation for the passthrough.

Relevant logs/screenshots

Linked Issue

issue

Upgrade Notices

Thanos was converted to the Big Bang passthrough pattern. Any values intended for the upstream Bitnami Thanos chart must now live under thanos.values.upstream instead of directly under thanos.values.

e.g.

addons:
  thanos:
    enabled: true
    values:
      upstream:
        query:
          enabled: true
        compactor:
          enabled: true

Thanos upstream chart dependency is now vendored locally

This MR updates the aliased upstream Bitnami Thanos chart from 17.3.1 to 17.4.0, but the more important maintenance change is that the upstream chart is no longer pulled from Bitnami's OCI registry.

Bitnami no longer publishes the Thanos chart to the OCI source previously referenced by this package, so the package now uses a vendored local chart tarball instead:

• Previous dependency source: oci://registry-1.docker.io/bitnamicharts
• New dependency source: file://./charts
• Vendored artifact: chart/charts/thanos-17.4.0.tgz

Impact

This change should not require any deployment-time values changes for Big Bang consumers.

The impact is for package maintainers:

• Do not use helm dependency update ./chart to refresh the upstream thanos dependency anymore.
• Future Thanos chart upgrades must be performed by manually vendoring the updated upstream Bitnami chart tarball into chart/charts/ and updating chart/Chart.yaml and chart/Chart.lock accordingly.
• docs/DEVELOPMENT_MAINTENANCE.md has been updated to document the new workflow.

Action required

• End users: no action required beyond normal validation for the Thanos chart update.
• Maintainers: follow the new manual vendored tarball workflow documented in docs/DEVELOPMENT_MAINTENANCE.md for future upstream Thanos chart updates.