feat(backup): move off-cluster DR to Cloudflare R2 (operator decision 2026-09-05)

"That's where backups will go for the time being until a better on-prem backup
solution is created." Two reasons beyond the (negligible) cost:

  1. Prod CANNOT reach the on-Proxmox MinIO. Prod is on the SOHO network
     192.168.2.0/24 — pfSense's WAN — while that MinIO sits inside pfSense's LAN.
     Measured from a pod inside prod: connection timed out after 15s. R2 needs no
     firewall change.
  2. That MinIO runs on the SAME Proxmox host as dev's VMs, so dev's
     "off-cluster" backup shared a physical failure domain with dev — one host
     loss took the cluster AND its backups. R2 is genuinely off-site.

COST, measured rather than estimated (read straight out of the buckets):
  velero  4.0 GiB / 6,264 objects  (7d retention; 8.65 GB live -> kopia dedup)
  cnpg    211 MiB / 1,755 objects  (keycloak 66Mi/331, nextcloud 87Mi/1329,
                                    semaphore 58Mi/95; ~7d of a 30d window)
Both clusters project to ~13-15 GiB and ~30k writes/month => pennies on R2, and
free egress means restore REHEARSALS cost nothing, so R-STATE-03 has no financial
disincentive to stay proven. Wasabi/Hetzner are 50-200x worse here purely because
of 1 TB minimums; Glacier tiers are a trap (90-day minimum billing against a
7-day Velero retention plus early-delete fees on 30-day WAL pruning).

*** THE R2 GOTCHA, WIRED UP FRONT: checksumAlgorithm: "" ***
velero-plugin-for-aws v1.14.2 bundles an AWS SDK that sends
x-amz-sdk-checksum-algorithm / x-amz-checksum-crc32 on every PUT. R2 REJECTS
those with HTTP 400 InvalidArgument, so every backup and every kopia blob upload
would fail. Set unconditionally — MinIO ignores it, so it needs no fork.

`region` was hardcoded us-east-1 inside the Velero HelmRelease: correct-by-
accident for MinIO (which ignores it) and WRONG for R2 (which demands exactly
`auto`). Now the S3_BACKUP_REGION knob.

PREFIXES ARE NOW SYMMETRIC (dev/prod), reversing the reasoning from two commits
ago. While the target was MinIO, dev HAD to keep the bucket root or it would
orphan the backups its proven restore depends on. R2 starts BOTH clusters on an
empty bucket, so there is no history to orphan — and leaving the bucket root
unused means a misrendered prefix lands somewhere obviously wrong instead of
silently colliding with a real environment.

NEITHER OVERLAY PINS THE ENDPOINT ANY MORE — a deliberate reversal of this
repo's "prod must never inherit base" rule. That rule exists because base
defaults are dev's LAN addresses; R2 is a single environment-INDEPENDENT endpoint,
so under R-ENV-02 it belongs in base, and two copies of one URL is a rotation
waiting to drift. Isolation comes from the path knobs, not the URL. Caught while
verifying: dev's overlay DID still pin MinIO, so dev would have taken the new
`dev` prefix while writing to the old endpoint — orphaning its MinIO backups for
no benefit. That is why the endpoint and the prefixes must move in ONE commit.

*** MERGING THIS RESETS DEV'S PITR WINDOW. *** Dev's R2 prefix starts empty:
Velero writes a fresh kopia repo, CNPG takes new base backups, the 30-day Barman
window rebuilds from zero. The MinIO copy is NOT deleted and stays restorable by
pointing the endpoint back. Do not merge while dev's proven restore is the only
recovery path you rely on.

STILL BLOCKED ON THE OPERATOR: the endpoint is the loud placeholder
https://TBD-R2-ACCOUNT-ID.r2.cloudflarestorage.com. Creating the R2 buckets and
an API token needs Cloudflare account access I do not have (the token in this
repo is Zone:DNS scoped). Velero+R2 and CNPG-barman+R2 are also UNPROVEN here and
must be verified by an actual backup AND restore, not just an upload.

VERIFIED: full CI gate PASS. Rendered both overlays — dev dev/s3://cnpg/dev,
prod prod/s3://cnpg/prod, region auto, one shared endpoint.

Refs R-STATE-03, R-ENV-02, R-IDP-05.

Co-Authored-By: Claude Opus 5 <[email protected]>

clusters/dev/kustomization.yaml

@@ -266,11 +266,20 @@ patches:
       - op: replace
         path: /data/CRAFTY_L4_VIP
         value: "192.168.1.55"
-      # Off-cluster backup target: the on-Proxmox MinIO (plain HTTP, path-style) that every CNPG
-      # barmanObjectStore and Velero's backupStorageLocation write to.
-      - op: replace
-        path: /data/S3_BACKUP_ENDPOINT
-        value: "http://192.168.1.9:9000"
+      # OFF-CLUSTER BACKUP TARGET — no op here any more, deliberately.
+      #
+      # This used to pin the on-Proxmox MinIO (http://192.168.1.9:9000). As of 2026-09-05 the operator
+      # moved backups to Cloudflare R2 "for the time being until a better on-prem backup solution is
+      # created", and R2 is a single environment-INDEPENDENT endpoint: both clusters write to the same
+      # buckets and are isolated by VELERO_BACKUP_PREFIX / CNPG_BACKUP_PATH (dev vs prod), not by URL.
+      # Under R-ENV-02 a value that does not differ per environment belongs in base and must NOT be
+      # restated here — two copies of one endpoint is just a rotation waiting to drift.
+      #
+      # *** MERGING THIS RESETS DEV'S PITR WINDOW. *** Dev's R2 prefix starts EMPTY, so Velero writes a
+      # fresh kopia repository and CNPG takes new base backups; the 30-day Barman window rebuilds from
+      # zero. The existing MinIO copy is NOT deleted and stays restorable — point S3_BACKUP_ENDPOINT
+      # back at http://192.168.1.9:9000 (and VELERO_BACKUP_PREFIX back to "") to reach it. Do not merge
+      # this while dev's proven restore is the only recovery path you are relying on.
       # dev mirrors prod's 3-node topology, so the replicated tier keeps 3 replicas.
       - op: replace
         path: /data/LONGHORN_DEFAULT_REPLICA_COUNT