K8SPG-691: add repo host autoscaling

[pooknull]

DESCRIPTION

This PR adds autoscaling for pgbackrest PVCs. It follows the pgdata PVC autoscaling logic.

When the AutoGrowVolumes feature gate is enabled and spec.backups.pgbackrest.repos[].volume.volumeClaimSpec.resources.limits.storage is configured:

• A script running in the pgbackrest-config container checks disk usage every five seconds.
• When usage exceeds 75%, the script calculates a new desired size by increasing the current volume size by 50% and writes it to the repo-host pod annotation suggested-pgbackrest-<repo-name>-pvc-size
• The annotation update triggers reconcile. The operator increases the PVCs resources.requests.storage to the suggested size
• The operator saves the latest suggestion in status.pgbackrest.repos[].desiredRepoVolume

CHECKLIST

Jira

• Is the Jira ticket created and referenced properly?
• Does the Jira ticket have the proper statuses for documentation (Needs Doc) and QA (Needs QA)?
• Does the Jira ticket link to the proper milestone (Fix Version field)?

Tests

• Is an E2E test/test case added for the new feature/change?
• Are unit tests added where appropriate?

Config/Logging/Testability

• Are all needed new/changed options added to default YAML files?
• Are all needed new/changed options added to the Helm Chart?
• Did we add proper logging messages for operator actions?
• Did we ensure compatibility with the previous version or cluster upgrade process?
• Does the change support oldest and newest supported PG version?
• Does the change support oldest and newest supported Kubernetes version?

[Copilot]

Pull request overview

Adds repo-host (pgBackRest) PVC autoscaling support to the operator, mirroring the existing pgdata autogrow behavior by having the repo-host Pod suggest a larger size via annotations and having the controller apply the resized PVC request while persisting the latest suggestion in status.

Changes:

• Add repo-host monitoring script that periodically computes and PATCHes suggested-pgbackrest-<repo>-pvc-size annotations when volume usage is high (feature-gated).
• Teach the PostgresCluster controller to observe suggested sizes from repo-host Pods, cap them by configured limits, apply updated PVC requests, and store the latest suggestion in status.pgbackrest.repos[].desiredRepoVolume.
• Extend repo-host RBAC and add unit + KUTTL E2E coverage for the new behavior.

Reviewed changes

Copilot reviewed 27 out of 28 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
pkg/apis/upstream.pgv2.percona.com/v1beta1/pgbackrest_types.go	Adds DesiredRepoVolume to repo status to persist observed suggestions.
internal/pgbackrest/reconcile.go	Threads autogrow-enabled repo names into pgBackRest config container script generation.
internal/pgbackrest/reconcile_test.go	Unit test ensuring autogrow monitoring is only injected for eligible repos and only on repo-host.
internal/pgbackrest/rbac.go	Grants repo-host ServiceAccount patch on pods to allow annotation updates.
internal/pgbackrest/rbac_test.go	Updates RBAC test expectations for added patch verb.
internal/pgbackrest/config.go	Injects monitor_volume function + per-repo calls into reload loop and PATCHes pod annotations.
internal/pgbackrest/config_test.go	Expands shellcheck coverage for reload script with/without autogrow repos.
internal/naming/annotations.go	Adds helpers for suggested-size annotation naming and parsing.
internal/controller/postgrescluster/watches.go	Triggers reconcile when suggested repo-host volume annotations change.
internal/controller/postgrescluster/watches_test.go	Verifies the new watch behavior enqueues reconciliation on suggestion changes.
internal/controller/postgrescluster/pgbackrest.go	Observes desired repo volumes from Pods/status, applies capped PVC request changes, persists desired size in status.
internal/controller/postgrescluster/pgbackrest_test.go	Adds targeted unit coverage for setRepoVolumeSize and repo-host SA/mount behavior.
e2e-tests/tests/repo-host-autogrow/00-deploy-operator.yaml	Enables AutoGrowVolumes in E2E deployment.
e2e-tests/tests/repo-host-autogrow/00-assert.yaml	Asserts operator is running before test proceeds.
e2e-tests/tests/repo-host-autogrow/01-create-cluster.yaml	Creates cluster with repo PVC request+limit configured to exercise autogrow.
e2e-tests/tests/repo-host-autogrow/01-assert.yaml	Waits for cluster + repo-host StatefulSet readiness.
e2e-tests/tests/repo-host-autogrow/02-grow-repo-volume.yaml	Fills repo volume to exceed threshold and trigger suggestion logic.
e2e-tests/tests/repo-host-autogrow/02-assert.yaml	Asserts suggestion annotation appears and is above expected floor; cleans up fill file.
e2e-tests/tests/repo-host-autogrow/03-assert.yaml	Asserts controller persists suggestion into PostgresCluster status and PVC request is updated.
e2e-tests/tests/repo-host-autogrow/99-remove-cluster-gracefully.yaml	Cleans up cluster/operator and checks for panics.
e2e-tests/run-release.csv	Adds the new E2E test to release runs.
e2e-tests/run-pr.csv	Adds the new E2E test to PR runs.
deploy/cw-bundle.yaml	CRD bundle regeneration for new status field.
deploy/crd.yaml	CRD regeneration for new status field.
deploy/bundle.yaml	CRD bundle regeneration for new status field.
config/crd/bases/upstream.pgv2.percona.com_postgresclusters.yaml	Base CRD updated with new status field schema.
config/crd/bases/pgv2.percona.com_perconapgclusters.yaml	Base CRD updated with new status field schema.
build/crd/percona/generated/pgv2.percona.com_perconapgclusters.yaml	Generated CRD updated with new status field schema.

[mayankshah1607]

what happens if the flag is disabled after a resize? It looks like we return nil here and later in setRepoVolumeSize we read the size from the spec (not actual pvc size), won't that cause a downscale and possibly break reconciliation?

[pooknull]

787be3a

[oksana-grishchenko]

Agree with Mayank's concern about disabling feature gate after resizing, that is a possible real life scenario, please consider it.
Other than that LGTM

[JNKPercona]

Test Name	Result	Time
backup-enable-disable	passed	00:11:33
builtin-extensions	passed	00:06:17
cert-manager-tls	failure	00:00:00
custom-envs	passed	00:20:10
custom-tls	passed	00:07:53
database-init-sql	passed	00:02:20
demand-backup	passed	00:27:23
demand-backup-offline-snapshot	passed	00:13:31
dynamic-configuration	passed	00:04:12
finalizers	passed	00:03:42
init-deploy	passed	00:03:00
huge-pages	passed	00:02:54
major-upgrade-14-to-15	passed	00:13:56
major-upgrade-15-to-16	passed	00:10:55
major-upgrade-16-to-17	passed	00:10:54
major-upgrade-17-to-18	passed	00:09:24
ldap	passed	00:05:43
ldap-tls	passed	00:05:35
monitoring	passed	00:08:19
monitoring-pmm3	passed	00:08:56
one-pod	passed	00:06:30
repo-host-autogrow	failure	00:02:23
operator-self-healing	passed	00:10:43
pgbouncer-mtls	passed	00:03:24
pitr	passed	00:12:38
scaling	passed	00:05:17
scheduled-backup	passed	00:34:42
self-healing	passed	00:08:46
sidecars	passed	00:02:48
standby-pgbackrest	passed	00:20:48
standby-streaming	passed	00:14:24
start-from-backup	passed	00:13:39
tablespaces	passed	00:07:32
telemetry-transfer	passed	00:04:44
upgrade-consistency	passed	00:06:57
upgrade-minor	passed	00:07:47
users	passed	00:05:06
migration-from-crunchy-standby	passed	00:21:26
migration-from-crunchy-pv	passed	00:08:30
migration-from-crunchy-backup-restore	passed	00:17:06

Summary	Value
Tests Run	40/40
Job Duration	02:35:23
Total Test Time	06:32:10

commit: eed13b0
image: perconalab/percona-postgresql-operator:PR-1689-eed13b0a8