feat: honor the operator's check_empty_wal_archive decision (#1009)

Archive() and the restore job hook each re-derived, on their own,
whether to verify the WAL archive destination is empty, by reading a
Cluster annotation and, for Archive, an on-disk marker file. That
decision belongs to the operator, which already tracks both the
annotation and the marker file's lifecycle.

Honor cnpg-i's new WALArchiveRequest/RestoreRequest field
CheckEmptyWalArchive when the operator sets it: obey it directly,
without re-inspecting the marker file. Only fall back to the previous
annotation-and-marker-file logic when talking to an operator that
predates this field.

Related: cloudnative-pg/cnpg-i#353 adds the field this depends on;
cloudnative-pg/cloudnative-pg#11216 is the operator-side counterpart.

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>
Signed-off-by: Armando Ruocco <armando.ruocco@enterprisedb.com>
Co-authored-by: Armando Ruocco <armando.ruocco@enterprisedb.com>

internal/cnpgi/common/wal.go

@@ -156,13 +156,17 @@ func (w WALServiceImplementation) Archive(
 		return nil, err
 	}
 
-	// Step 2: Check if the archive location is safe to perform archiving
-	checkFileExisting, err := fileutils.FileExists(emptyWalArchiveFile)
+	// Step 2: Check if the archive location is safe to perform archiving.
+	checkEmptyWalArchive, err := resolveArchiveEmptyWalArchiveCheck(
+		request.CheckEmptyWalArchive,
+		configuration.Cluster,
+		emptyWalArchiveFile,
+	)
 	if err != nil {
-		return nil, fmt.Errorf("while checking for empty wal archive check file %q: %w", emptyWalArchiveFile, err)
+		return nil, err
 	}
 
-	if utils.IsEmptyWalArchiveCheckEnabled(&configuration.Cluster.ObjectMeta) && checkFileExisting {
+	if checkEmptyWalArchive {
 		if err := CheckBackupDestination(
 			ctx,
 			&objectStore.Spec.Configuration,
@@ -224,6 +228,31 @@ func (w WALServiceImplementation) Archive(
 	return &wal.WALArchiveResult{}, nil
 }
 
+// resolveArchiveEmptyWalArchiveCheck reports whether the WAL archive
+// destination must be verified before archiving this segment.
+//
+// The operator owns the marker file's lifecycle, so when it sets the decision
+// (non-nil) that value already accounts for the marker and is obeyed as-is. A
+// nil value comes from an operator that predates this field, so we fall back to
+// the previous logic: the Cluster annotation combined with the on-disk marker
+// file.
+func resolveArchiveEmptyWalArchiveCheck(
+	operatorDecision *bool,
+	cluster *cnpgv1.Cluster,
+	markerFilePath string,
+) (bool, error) {
+	if operatorDecision != nil {
+		return *operatorDecision, nil
+	}
+
+	markerFilePresent, err := fileutils.FileExists(markerFilePath)
+	if err != nil {
+		return false, fmt.Errorf("while checking for empty wal archive check file %q: %w", markerFilePath, err)
+	}
+
+	return utils.IsEmptyWalArchiveCheckEnabled(&cluster.ObjectMeta) && markerFilePresent, nil
+}
+
 // Restore implements the WALService interface
 func (w WALServiceImplementation) Restore(
 	ctx context.Context,

internal/cnpgi/common/wal_test.go

@@ -21,15 +21,20 @@ package common
 
 import (
 	"context"
+	"os"
+	"path/filepath"
 
 	barmanapi "github.com/cloudnative-pg/barman-cloud/pkg/api"
 	barmanRestorer "github.com/cloudnative-pg/barman-cloud/pkg/restorer"
 	cnpgv1 "github.com/cloudnative-pg/cloudnative-pg/api/v1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+	"k8s.io/utils/ptr"
+
+	"github.com/cloudnative-pg/plugin-barman-cloud/internal/cnpgi/metadata"
+	"github.com/cloudnative-pg/plugin-barman-cloud/internal/cnpgi/operator/config"
+
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-
-	"github.com/cloudnative-pg/plugin-barman-cloud/internal/cnpgi/operator/config"
 )
 
 var _ = Describe("resolveRestoreObjectStore", func() {
@@ -177,3 +182,65 @@ var _ = Describe("clearEndOfWALStreamFlag", func() {
 		Expect(isEOS).To(BeFalse())
 	})
 })
+
+var _ = Describe("resolveArchiveEmptyWalArchiveCheck", func() {
+	// skipAnnotation mirrors the unexported constant in cloudnative-pg's
+	// pkg/utils; hard-coding the literal makes a divergence surface as a
+	// failing test rather than silently disabling the check.
+	const skipAnnotation = "cnpg.io/skipEmptyWalArchiveCheck"
+
+	clusterWith := func(annotationValue *string) *cnpgv1.Cluster {
+		cluster := &cnpgv1.Cluster{}
+		if annotationValue != nil {
+			cluster.Annotations = map[string]string{skipAnnotation: *annotationValue}
+		}
+		return cluster
+	}
+
+	// markerPath returns the marker file path inside a fresh temp dir,
+	// creating the file there when present is true.
+	markerPath := func(present bool) string {
+		filePath := filepath.Join(GinkgoT().TempDir(), metadata.CheckEmptyWalArchiveFile)
+		if present {
+			Expect(os.WriteFile(filePath, []byte{}, 0o600)).To(Succeed())
+		}
+		return filePath
+	}
+
+	When("the operator sets the decision", func() {
+		It("obeys true, ignoring the annotation and the marker file", func() {
+			// annotation would skip the check and the marker is absent, yet the
+			// operator's explicit true must still win.
+			got, err := resolveArchiveEmptyWalArchiveCheck(
+				ptr.To(true), clusterWith(ptr.To("enabled")), markerPath(false))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(got).To(BeTrue())
+		})
+
+		It("obeys false, ignoring the annotation and the marker file", func() {
+			// annotation would keep the check on and the marker is present, yet the
+			// operator's explicit false must still win.
+			got, err := resolveArchiveEmptyWalArchiveCheck(
+				ptr.To(false), clusterWith(nil), markerPath(true))
+			Expect(err).NotTo(HaveOccurred())
+			Expect(got).To(BeFalse())
+		})
+	})
+
+	When("the operator predates the field (nil decision)", func() {
+		DescribeTable(
+			"falls back to the annotation combined with the marker file",
+			func(annotationValue *string, markerPresent bool, expected bool) {
+				got, err := resolveArchiveEmptyWalArchiveCheck(
+					nil, clusterWith(annotationValue), markerPath(markerPresent))
+				Expect(err).NotTo(HaveOccurred())
+				Expect(got).To(Equal(expected))
+			},
+			Entry("no annotation and marker present: check runs", nil, true, true),
+			Entry("no annotation and marker absent: check skipped", nil, false, false),
+			Entry("opt-out annotation and marker present: check skipped", ptr.To("enabled"), true, false),
+			Entry("unrelated annotation value and marker present: check runs", ptr.To("something-else"), true, true),
+			Entry("empty annotation value and marker present: check runs", ptr.To(""), true, true),
+		)
+	})
+})

internal/cnpgi/restore/restore.go

@@ -113,6 +113,7 @@ func (impl JobHookImpl) Restore(
 			configuration.Cluster,
 			&targetObjectStore.Spec.Configuration,
 			targetObjectStore.Name,
+			req.CheckEmptyWalArchive,
 		); err != nil {
 			return nil, err
 		}
@@ -250,6 +251,7 @@ func (impl *JobHookImpl) checkBackupDestination(
 	cluster *cnpgv1.Cluster,
 	barmanConfiguration *cnpgv1.BarmanObjectStoreConfiguration,
 	objectStoreName string,
+	operatorCheckEmptyWalArchive *bool,
 ) error {
 	// Get environment from cache
 	env, err := barmanCredentials.EnvSetCloudCredentialsAndCertificates(ctx,
@@ -288,14 +290,26 @@ func (impl *JobHookImpl) checkBackupDestination(
 		}
 	}
 
-	// Check if we're ok to archive in the desired destination
-	if utils.IsEmptyWalArchiveCheckEnabled(&cluster.ObjectMeta) {
+	if resolveRestoreEmptyWalArchiveCheck(operatorCheckEmptyWalArchive, cluster) {
 		return common.CheckBackupDestination(ctx, barmanConfiguration, walArchiver, serverName)
 	}
 
 	return nil
 }
 
+// resolveRestoreEmptyWalArchiveCheck reports whether the destination must be
+// verified before restoring. When the operator sets the decision (non-nil) it
+// is obeyed as-is; a nil value comes from an operator that predates this field,
+// so we fall back to the Cluster annotation. Unlike archiving, restore is a
+// one-shot operation that has never been gated on the first-archive marker
+// file, so the annotation is the only fallback needed.
+func resolveRestoreEmptyWalArchiveCheck(operatorDecision *bool, cluster *cnpgv1.Cluster) bool {
+	if operatorDecision != nil {
+		return *operatorDecision
+	}
+	return utils.IsEmptyWalArchiveCheckEnabled(&cluster.ObjectMeta)
+}
+
 // restoreCustomWalDir moves the current pg_wal data to the specified custom wal dir and applies the symlink
 // returns indicating if any changes were made and any error encountered in the process
 func (impl JobHookImpl) restoreCustomWalDir(ctx context.Context) (bool, error) {

internal/cnpgi/restore/restore_test.go

@@ -0,0 +1,66 @@
+/*
+Copyright © contributors to CloudNativePG, established as
+CloudNativePG a Series of LF Projects, LLC.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package restore
+
+import (
+	cnpgv1 "github.com/cloudnative-pg/cloudnative-pg/api/v1"
+	"k8s.io/utils/ptr"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+var _ = Describe("resolveRestoreEmptyWalArchiveCheck", func() {
+	// skipAnnotation mirrors the unexported constant in cloudnative-pg's
+	// pkg/utils; hard-coding the literal makes a divergence surface as a
+	// failing test rather than silently disabling the check.
+	const skipAnnotation = "cnpg.io/skipEmptyWalArchiveCheck"
+
+	clusterWith := func(annotationValue *string) *cnpgv1.Cluster {
+		cluster := &cnpgv1.Cluster{}
+		if annotationValue != nil {
+			cluster.Annotations = map[string]string{skipAnnotation: *annotationValue}
+		}
+		return cluster
+	}
+
+	When("the operator sets the decision", func() {
+		It("obeys true even when the annotation would skip the check", func() {
+			Expect(resolveRestoreEmptyWalArchiveCheck(ptr.To(true), clusterWith(ptr.To("enabled")))).To(BeTrue())
+		})
+
+		It("obeys false even when the annotation would keep the check on", func() {
+			Expect(resolveRestoreEmptyWalArchiveCheck(ptr.To(false), clusterWith(nil))).To(BeFalse())
+		})
+	})
+
+	When("the operator predates the field (nil decision)", func() {
+		DescribeTable(
+			"falls back to the Cluster annotation, never to a marker file",
+			func(annotationValue *string, expected bool) {
+				Expect(resolveRestoreEmptyWalArchiveCheck(nil, clusterWith(annotationValue))).To(Equal(expected))
+			},
+			Entry("no annotation: check runs", nil, true),
+			Entry("opt-out annotation: check skipped", ptr.To("enabled"), false),
+			Entry("unrelated annotation value: check runs", ptr.To("something-else"), true),
+			Entry("empty annotation value: check runs", ptr.To(""), true),
+		)
+	})
+})

internal/cnpgi/restore/suite_test.go

@@ -0,0 +1,32 @@
+/*
+Copyright © contributors to CloudNativePG, established as
+CloudNativePG a Series of LF Projects, LLC.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+
+SPDX-License-Identifier: Apache-2.0
+*/
+
+package restore
+
+import (
+	"testing"
+
+	. "github.com/onsi/ginkgo/v2"
+	. "github.com/onsi/gomega"
+)
+
+func TestRestore(t *testing.T) {
+	RegisterFailHandler(Fail)
+	RunSpecs(t, "Restore job hook test suite")
+}