chore(lint): address findings from prealloc linter (cloudnative-pg#9680)

golangci-lint 2.8.0 enables the prealloc linter.

Signed-off-by: Marco Nenciarini <marco.nenciarini@enterprisedb.com>

Author: mnencia

internal/cmd/manager/instance/upgrade/execute/cmd.go

@@ -446,13 +446,14 @@ func prepareConfigurationFiles(ctx context.Context, cluster apiv1.Cluster, destD
 func (ui upgradeInfo) runPgUpgrade(
 	newDataDir string,
 ) error {
-	args := []string{
+	args := make([]string, 0, 9+len(ui.pgUpgradeArgs))
+	args = append(args,
 		"--link",
 		"--username", "postgres",
 		"--old-bindir", ui.oldBinDir,
 		"--old-datadir", ui.pgData,
 		"--new-datadir", newDataDir,
-	}
+	)
 	args = append(args, ui.pgUpgradeArgs...)
 
 	// Run the pg_upgrade command

internal/cmd/plugin/logical/psql.go

@@ -65,13 +65,14 @@ func getSQLCommand(
 	sqlCommand string,
 	args ...string,
 ) (*psql.Command, error) {
-	psqlArgs := []string{
+	psqlArgs := make([]string, 0, 5+len(args))
+	psqlArgs = append(psqlArgs,
 		connectionString,
 		"-U",
 		"postgres",
 		"-c",
 		sqlCommand,
-	}
+	)
 	psqlArgs = append(psqlArgs, args...)
 	psqlOptions := psql.CommandOptions{
 		Replica:     false,

pkg/management/postgres/instance.go

@@ -1136,11 +1136,12 @@ func (instance *Instance) Rewind(ctx context.Context) error {
 	instance.LogPgControldata(ctx, "before pg_rewind")
 
 	primaryConnInfo := instance.GetPrimaryConnInfo()
-	options := []string{
+	options := make([]string, 0, 6)
+	options = append(options,
 		"-P",
 		"--source-server", primaryConnInfo,
 		"--target-pgdata", instance.PgData,
-	}
+	)
 
 	// make sure restore_command is set in override.conf
 	if _, err := configurePostgresOverrideConfFile(instance.PgData, primaryConnInfo, ""); err != nil {

pkg/management/postgres/logicalimport/database.go

@@ -94,21 +94,23 @@ func (ds *databaseSnapshotter) exportDatabases(
 	extraOptions []string,
 ) error {
 	contextLogger := log.FromContext(ctx)
-	sectionsToExport := []string{}
+	sections := ds.getSectionsToExecute()
+	sectionsToExport := make([]string, 0, len(sections))
 
-	for _, section := range ds.getSectionsToExecute() {
+	for _, section := range sections {
 		sectionsToExport = append(sectionsToExport, fmt.Sprintf("--section=%s", section))
 	}
 
 	for _, database := range databases {
 		contextLogger.Info("exporting database", "databaseName", database)
 		dsn := target.GetDsn(database)
-		options := []string{
+		options := make([]string, 0, 6+len(sectionsToExport)+len(extraOptions))
+		options = append(options,
 			"-Fd",
 			"-f", generateFileNameForDatabase(database),
 			"-d", dsn,
 			"-v",
-		}
+		)
 		options = append(options, sectionsToExport...)
 		options = append(options, extraOptions...)
 
@@ -212,8 +214,6 @@ func (ds *databaseSnapshotter) importDatabaseContent(
 			"section", section,
 		)
 
-		var options []string
-
 		alwaysPresentOptions := []string{
 			"-U", "postgres",
 			"--no-owner",
@@ -224,7 +224,9 @@ func (ds *databaseSnapshotter) importDatabaseContent(
 			generateFileNameForDatabase(database),
 		}
 
-		options = append(options, flags.forSection(section)...)
+		sectionFlags := flags.forSection(section)
+		options := make([]string, 0, len(sectionFlags)+len(alwaysPresentOptions))
+		options = append(options, sectionFlags...)
 		options = append(options, alwaysPresentOptions...)
 
 		contextLogger.Info("Running pg_restore",

pkg/reconciler/majorupgrade/reconciler_test.go

@@ -75,10 +75,11 @@ var _ = Describe("Major upgrade job status reconciliation", func() {
 			buildReplicaPVC(3),
 		}
 
-		objects := []runtime.Object{
+		objects := make([]runtime.Object, 0, 2+len(pvcs))
+		objects = append(objects,
 			job,
 			cluster,
-		}
+		)
 		for i := range pvcs {
 			objects = append(objects, &pvcs[i])
 		}

pkg/specs/jobs.go

@@ -207,13 +207,15 @@ func CreatePrimaryJobViaRestoreSnapshot(
 
 // CreatePrimaryJobViaRecovery creates a new primary instance in a Pod, restoring from a Backup
 func CreatePrimaryJobViaRecovery(cluster apiv1.Cluster, nodeSerial int, backup *apiv1.Backup) *batchv1.Job {
-	initCommand := []string{
+	commonFlags := buildCommonInitJobFlags(cluster)
+	initCommand := make([]string, 0, 3+len(commonFlags))
+	initCommand = append(initCommand,
 		"/controller/manager",
 		"instance",
 		"restore",
-	}
+	)
 
-	initCommand = append(initCommand, buildCommonInitJobFlags(cluster)...)
+	initCommand = append(initCommand, commonFlags...)
 
 	job := CreatePrimaryJob(cluster, nodeSerial, jobRoleFullRecovery, initCommand)
 
@@ -248,41 +250,47 @@ func addBarmanEndpointCAToJobFromCluster(cluster apiv1.Cluster, backup *apiv1.Ba
 
 // CreatePrimaryJobViaPgBaseBackup creates a new primary instance in a Pod
 func CreatePrimaryJobViaPgBaseBackup(cluster apiv1.Cluster, nodeSerial int) *batchv1.Job {
-	initCommand := []string{
+	commonFlags := buildCommonInitJobFlags(cluster)
+	initCommand := make([]string, 0, 3+len(commonFlags))
+	initCommand = append(initCommand,
 		"/controller/manager",
 		"instance",
 		"pgbasebackup",
-	}
+	)
 
-	initCommand = append(initCommand, buildCommonInitJobFlags(cluster)...)
+	initCommand = append(initCommand, commonFlags...)
 
 	return CreatePrimaryJob(cluster, nodeSerial, jobRolePGBaseBackup, initCommand)
 }
 
 // JoinReplicaInstance create a new PostgreSQL node, copying the contents from another Pod
 func JoinReplicaInstance(cluster apiv1.Cluster, nodeSerial int) *batchv1.Job {
-	initCommand := []string{
+	commonFlags := buildCommonInitJobFlags(cluster)
+	initCommand := make([]string, 0, 5+len(commonFlags))
+	initCommand = append(initCommand,
 		"/controller/manager",
 		"instance",
 		"join",
 		"--parent-node", cluster.GetServiceReadWriteName(),
-	}
+	)
 
-	initCommand = append(initCommand, buildCommonInitJobFlags(cluster)...)
+	initCommand = append(initCommand, commonFlags...)
 
 	return CreatePrimaryJob(cluster, nodeSerial, jobRoleJoin, initCommand)
 }
 
 // RestoreReplicaInstance creates a new PostgreSQL replica starting from a volume snapshot backup
 func RestoreReplicaInstance(cluster apiv1.Cluster, nodeSerial int) *batchv1.Job {
-	initCommand := []string{
+	commonFlags := buildCommonInitJobFlags(cluster)
+	initCommand := make([]string, 0, 4+len(commonFlags))
+	initCommand = append(initCommand,
 		"/controller/manager",
 		"instance",
 		"restoresnapshot",
 		"--immediate",
-	}
+	)
 
-	initCommand = append(initCommand, buildCommonInitJobFlags(cluster)...)
+	initCommand = append(initCommand, commonFlags...)
 
 	job := CreatePrimaryJob(cluster, nodeSerial, jobRoleSnapshotRecovery, initCommand)
 	return job

tests/e2e/asserts_test.go

@@ -176,12 +176,12 @@ func AssertSwitchoverWithHistory(
 
 	if !isReplica {
 		By("confirming that the all postgres containers have *.history file after switchover", func() {
-			pods = []string{}
 			timeout := 120
 
 			// Gather pod names
 			podList, err := clusterutils.ListPods(env.Ctx, env.Client, namespace, clusterName)
 			Expect(len(podList.Items), err).To(BeEquivalentTo(oldPodListLength))
+			pods = make([]string, 0, len(podList.Items))
 			for _, p := range podList.Items {
 				pods = append(pods, p.Name)
 			}
@@ -2855,7 +2855,10 @@ func AssertClusterReplicationSlotsAligned(
 	podList, err := clusterutils.ListPods(env.Ctx, env.Client, namespace, clusterName)
 	Expect(err).ToNot(HaveOccurred())
 	Eventually(func(g Gomega) {
-		var lsnList []string
+		numPods := len(podList.Items)
+		// Capacity calculation: primary has (N-1) HA slots, each of the (N-1) replicas
+		// has (N-2) slots. Total LSNs: (N-1) + (N-1)*(N-2) = (N-1)^2
+		lsnList := make([]string, 0, (numPods-1)*(numPods-1))
 		for _, pod := range podList.Items {
 			out, err := replicationslot.GetReplicationSlotLsnsOnPod(
 				env.Ctx, env.Client, env.Interface, env.RestClientConfig,

tests/e2e/operator_ha_test.go

@@ -122,7 +122,7 @@ var _ = Describe("Operator High Availability", Serial,
 				Eventually(func() []string {
 					podList, err := podutils.List(env.Ctx, env.Client, operatorNamespace)
 					Expect(err).ToNot(HaveOccurred())
-					var podNames []string
+					podNames := make([]string, 0, len(podList.Items))
 					for _, podItem := range podList.Items {
 						podNames = append(podNames, podItem.GetName())
 					}

tests/e2e/tablespaces_test.go

@@ -947,7 +947,7 @@ func AssertClusterHasMountPointsAndVolumesForTablespaces(
 					))
 				}
 
-				var volumeNames []string
+				volumeNames := make([]string, 0, len(pod.Spec.Volumes))
 				var claimNames []string
 				for _, vol := range pod.Spec.Volumes {
 					volumeNames = append(volumeNames, vol.Name)

tests/e2e/upgrade_test.go

@@ -614,9 +614,9 @@ var _ = Describe("Upgrade", Label(tests.LabelUpgrade, tests.LabelNoOpenshift), O
 
 		assertPGBouncerPodsAreReady(upgradeNamespace, pgBouncerSampleFile, 2)
 
-		var podUIDs []types.UID
 		podList, err := clusterutils.ListPods(env.Ctx, env.Client, upgradeNamespace, clusterName1)
 		Expect(err).ToNot(HaveOccurred())
+		podUIDs := make([]types.UID, 0, len(podList.Items))
 		for _, pod := range podList.Items {
 			podUIDs = append(podUIDs, pod.GetUID())
 		}