feat(helm): flexible drivesPerNode topology with backward-compatible per-pool defaults (#4901)

* helm chart: one data drive per node - fix1

* refactor(helm): prevent negative or 0 replicaCount

Co-authored-by: Copilot <copilot@github.com>

* refactor(helm): remove env REPLICA_COUNT

* feat(helm): default no logs directory to force stdout

Co-authored-by: Copilot <copilot@github.com>

* feat(helm): add drivesPerNode

* feat(helm): correct default parity with 4 nodes /  1 drive per node

* conditional render of RUSTFS_OBS_LOG_DIRECTORY

* feat(chart): add table doc for parity

* fix(chart): handle invalid annotation objects

* fix(chart): move logging and obsevability options together; default for kubernetes output to stdout

* feat(chart): better table doc for parity

* fix(chart): leave RUSTFS_OBS_LOG_DIRECTORY empty, or the defaults will attempt to write to readonly fs

* fix(chart): chart defaults as the previous version: 4 nodes with 4 drives per node

* feat(chart): render RUSTFS_STORAGE_CLASS_STANDARD in configmap

* minor fix for pvcAnnotations

Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>
Signed-off-by: Cristian Chiru <cristi.chiru@gmail.com>

* fix(chart): better drivesPerNode handling

* fix(chart): obs_log_directory default non empty again to preserve previous deployments compatibility

* fix(chart): proper drivesPerNode impl

* fix(chart): values clarification for empty vs unset `obs_log_directory`

* feat(chart): add service externalIPs

* feat(helm): add optional service labels

* fix(helm): merge service labels

* fix(helm): storageclass pvcAnnotations

* fix(chart): move logging and obsevability options together; default for kubernetes output to stdout

* fix(helm): remove duplicate keys

* fix(helm): default drivesPerNode null, keep legacy chart behavior

* feat(helm): add template test for externalIPs

* fix(helm): per-pool drivesPerNode inference, restore regression tests

Repairs the drivesPerNode feature from #2693 so it renders and stays
upgrade-safe:

- define the missing drives inference (rustfs.poolDrives) and compute it
  per pool inside rustfs.pools, so mixed 4x4 + 16x1 pool deployments keep
  their exact legacy volumeClaimTemplates when drivesPerNode is unset
- restore the $poolsEnabled definition dropped in the rebase (chart failed
  to render at all)
- fix .Values references inside the pool range (dot is the pool there) and
  keep per-pool storageclass pvcAnnotations overrides working
- make rustfs.volumes derive the drive range from pool drives instead of
  the pod count, and relax the pools.list 4-or-16 restriction to >= 2
- reject drivesPerNode=0 explicitly instead of silently inferring
- keep default rendering identical to main: storage_class_standard stays
  unrendered by default, obs_endpoint.use_stdout stays false, clusterDomain
  value restored
- restore the clusterDomain/mTLS SAN/explicit-volumes regression tests that
  the branch deleted, keeping the new topology tests

---------

Signed-off-by: Cristian Chiru <cristi.chiru@gmail.com>
Co-authored-by: Cristian Chiru <cristi.chiru@gmail.com>
Co-authored-by: Copilot <copilot@github.com>
Co-authored-by: Copilot Autofix powered by AI <175728472+Copilot@users.noreply.github.com>

scripts/test_helm_templates.sh

@@ -303,3 +303,70 @@ if grep -q 'svc\.cluster\.local"' <<<"$cert_custom"; then
   echo "Custom clusterDomain must fully replace cluster.local in mTLS server cert SANs" >&2
   exit 1
 fi
+
+# Legacy topology compatibility: default replicaCount=4 (no drivesPerNode set)
+# must render the old 4x4 PVC names (data-rustfs-0 .. data-rustfs-3).
+legacy_four_by_four=$(render_distributed_statefulset)
+for i in 0 1 2 3; do
+  if ! grep -q "name: data-rustfs-${i}" <<<"$legacy_four_by_four"; then
+    echo "Legacy 4x4 topology must contain PVC data-rustfs-${i}" >&2
+    exit 1
+  fi
+done
+if grep -q "name: data$" <<<"$legacy_four_by_four"; then
+  echo "Legacy 4x4 topology must NOT contain a single 'data' PVC" >&2
+  exit 1
+fi
+
+# Legacy topology compatibility: replicaCount=16 (no drivesPerNode set)
+# must render a single 'data' PVC (old 16x1 behaviour).
+legacy_sixteen_by_one=$(render_distributed_statefulset --set replicaCount=16)
+if ! grep -q "name: data$" <<<"$legacy_sixteen_by_one"; then
+  echo "Legacy 16x1 topology must contain a single 'data' PVC" >&2
+  exit 1
+fi
+if grep -q "name: data-rustfs-" <<<"$legacy_sixteen_by_one"; then
+  echo "Legacy 16x1 topology must NOT contain data-rustfs-* PVCs" >&2
+  exit 1
+fi
+
+# Generic topology: explicit replicaCount=8 drivesPerNode=2 must render
+# exactly two PVCs per pod.
+generic_eight_by_two=$(render_distributed_statefulset --set replicaCount=8 --set drivesPerNode=2)
+for i in 0 1; do
+  if ! grep -q "name: data-rustfs-${i}" <<<"$generic_eight_by_two"; then
+    echo "Generic 8x2 topology must contain PVC data-rustfs-${i}" >&2
+    exit 1
+  fi
+done
+if grep -q "name: data$" <<<"$generic_eight_by_two"; then
+  echo "Generic 8x2 topology must NOT contain a single 'data' PVC" >&2
+  exit 1
+fi
+
+# volumeClaimTemplates must not contain empty annotations when pvcAnnotations are unset,
+# because Kubernetes treats annotations: {} as a mutation of the immutable field.
+no_ann_output=$(render_distributed_statefulset)
+if grep -A1 'kind: PersistentVolumeClaim' <<<"$no_ann_output" | grep -q 'annotations:'; then
+  echo "Empty pvcAnnotations must not render an annotations key in volumeClaimTemplates" >&2
+  exit 1
+fi
+
+# Distributed mode with replicaCount < 2 must fail rendering.
+low_replica_status=0
+render_distributed_statefulset --set replicaCount=1 >/dev/null 2>&1 || low_replica_status=$?
+if [[ $low_replica_status -eq 0 ]]; then
+  echo "Distributed mode with replicaCount=1 must fail rendering" >&2
+  exit 1
+fi
+
+# service.externalIPs must render correctly when supplied.
+external_ips_output=$(helm template rustfs "$CHART_DIR" \
+  --namespace rustfs \
+  --set secret.rustfs.access_key=test-access-key \
+  --set secret.rustfs.secret_key=test-secret-key \
+  --set 'service.externalIPs[0]=203.0.113.1')
+if ! grep -A2 'externalIPs:' <<<"$external_ips_output" | grep -q '203.0.113.1'; then
+  echo "service.externalIPs must contain 203.0.113.1" >&2
+  exit 1
+fi