Linter-induced code refactoring, run round 2. (#360)

Run more linters in the gometalinter, i.e. deadcode, megacheck,
nakedret, dup.

More consistent code formatting, remove two dead functions, eliminate
naked a bunch of naked returns, refactor a few functions to avoid code
duplication.

pkg/cluster/cluster.go

@@ -450,8 +450,8 @@ func (c *Cluster) compareContainers(setA, setB *v1beta1.StatefulSet) (bool, []st
 	return needsRollUpdate, reasons
 }
 
-func compareResources(a *v1.ResourceRequirements, b *v1.ResourceRequirements) (equal bool) {
-	equal = true
+func compareResources(a *v1.ResourceRequirements, b *v1.ResourceRequirements) bool {
+	equal := true
 	if a != nil {
 		equal = compareResoucesAssumeFirstNotNil(a, b)
 	}
@@ -459,7 +459,7 @@ func compareResources(a *v1.ResourceRequirements, b *v1.ResourceRequirements) (e
 		equal = compareResoucesAssumeFirstNotNil(b, a)
 	}
 
-	return
+	return equal
 }
 
 func compareResoucesAssumeFirstNotNil(a *v1.ResourceRequirements, b *v1.ResourceRequirements) bool {
@@ -786,7 +786,8 @@ func (c *Cluster) initInfrastructureRoles() error {
 }
 
 // resolves naming conflicts between existing and new roles by chosing either of them.
-func (c *Cluster) resolveNameConflict(currentRole, newRole *spec.PgUser) (result spec.PgUser) {
+func (c *Cluster) resolveNameConflict(currentRole, newRole *spec.PgUser) spec.PgUser {
+	var result spec.PgUser
 	if newRole.Origin >= currentRole.Origin {
 		result = *newRole
 	} else {
@@ -794,7 +795,7 @@ func (c *Cluster) resolveNameConflict(currentRole, newRole *spec.PgUser) (result
 	}
 	c.logger.Debugf("resolved a conflict of role %q between %s and %s to %s",
 		newRole.Name, newRole.Origin, currentRole.Origin, result.Origin)
-	return
+	return result
 }
 
 func (c *Cluster) shouldAvoidProtectedOrSystemRole(username, purpose string) bool {
@@ -838,8 +839,9 @@ func (c *Cluster) GetStatus() *spec.ClusterStatus {
 }
 
 // Switchover does a switchover (via Patroni) to a candidate pod
-func (c *Cluster) Switchover(curMaster *v1.Pod, candidate spec.NamespacedName) (err error) {
+func (c *Cluster) Switchover(curMaster *v1.Pod, candidate spec.NamespacedName) error {
 
+	var err error
 	c.logger.Debugf("failing over from %q to %q", curMaster.Name, candidate)
 
 	var wg sync.WaitGroup
@@ -858,8 +860,8 @@ func (c *Cluster) Switchover(curMaster *v1.Pod, candidate spec.NamespacedName) (
 
 		select {
 		case <-stopCh:
-		case podLabelErr <- func() (err error) {
-			_, err = c.waitForPodLabel(ch, stopCh, &role)
+		case podLabelErr <- func() (err2 error) {
+			_, err2 = c.waitForPodLabel(ch, stopCh, &role)
 			return
 		}():
 		}
@@ -882,7 +884,7 @@ func (c *Cluster) Switchover(curMaster *v1.Pod, candidate spec.NamespacedName) (
 	// close the label waiting channel no sooner than the waiting goroutine terminates.
 	close(podLabelErr)
 
-	return
+	return err
 
 }
 

pkg/cluster/k8sres.go

@@ -7,13 +7,13 @@ import (
 
 	"github.com/Sirupsen/logrus"
 
+	"k8s.io/api/apps/v1beta1"
+	"k8s.io/api/core/v1"
+	policybeta1 "k8s.io/api/policy/v1beta1"
 	"k8s.io/apimachinery/pkg/api/resource"
 	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 	"k8s.io/apimachinery/pkg/types"
 	"k8s.io/apimachinery/pkg/util/intstr"
-	"k8s.io/api/core/v1"
-	"k8s.io/api/apps/v1beta1"
-	policybeta1 "k8s.io/api/policy/v1beta1"
 
 	"github.com/zalando-incubator/postgres-operator/pkg/spec"
 	"github.com/zalando-incubator/postgres-operator/pkg/util"
@@ -90,7 +90,7 @@ func (c *Cluster) makeDefaultResources() spec.Resources {
 	defaultRequests := spec.ResourceDescription{CPU: config.DefaultCPURequest, Memory: config.DefaultMemoryRequest}
 	defaultLimits := spec.ResourceDescription{CPU: config.DefaultCPULimit, Memory: config.DefaultMemoryLimit}
 
-	return spec.Resources{ResourceRequest:defaultRequests, ResourceLimits:defaultLimits}
+	return spec.Resources{ResourceRequest: defaultRequests, ResourceLimits: defaultLimits}
 }
 
 func generateResourceRequirements(resources spec.Resources, defaultResources spec.Resources) (*v1.ResourceRequirements, error) {
@@ -366,7 +366,7 @@ func generateSidecarContainers(sidecars []spec.Sidecar,
 	volumeMounts []v1.VolumeMount, defaultResources spec.Resources,
 	superUserName string, credentialsSecretName string, logger *logrus.Entry) ([]v1.Container, error) {
 
-	if sidecars != nil && len(sidecars) > 0 {
+	if len(sidecars) > 0 {
 		result := make([]v1.Container, 0)
 		for index, sidecar := range sidecars {
 
@@ -699,7 +699,7 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 	// generate sidecar containers
 	if sidecarContainers, err = generateSidecarContainers(sideCars, volumeMounts, defaultResources,
 		c.OpConfig.SuperUsername, c.credentialSecretName(c.OpConfig.SuperUsername), c.logger); err != nil {
-			return nil, fmt.Errorf("could not generate sidecar containers: %v", err)
+		return nil, fmt.Errorf("could not generate sidecar containers: %v", err)
 	}
 
 	tolerationSpec := tolerations(&spec.Tolerations, c.OpConfig.PodToleration)
@@ -716,7 +716,7 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 		int64(c.OpConfig.PodTerminateGracePeriod.Seconds()),
 		c.OpConfig.PodServiceAccountName,
 		c.OpConfig.KubeIAMRole,
-		effectivePodPriorityClassName); err != nil{
+		effectivePodPriorityClassName); err != nil {
 		return nil, fmt.Errorf("could not generate pod template: %v", err)
 	}
 
@@ -726,7 +726,7 @@ func (c *Cluster) generateStatefulSet(spec *spec.PostgresSpec) (*v1beta1.Statefu
 
 	if volumeClaimTemplate, err = generatePersistentVolumeClaimTemplate(spec.Volume.Size,
 		spec.Volume.StorageClass); err != nil {
-			return nil, fmt.Errorf("could not generate volume claim template: %v", err)
+		return nil, fmt.Errorf("could not generate volume claim template: %v", err)
 	}
 
 	numberOfInstances := c.getNumberOfInstances(spec)
@@ -804,11 +804,11 @@ func (c *Cluster) mergeSidecars(sidecars []spec.Sidecar) []spec.Sidecar {
 	return result
 }
 
-func (c *Cluster) getNumberOfInstances(spec *spec.PostgresSpec) (newcur int32) {
+func (c *Cluster) getNumberOfInstances(spec *spec.PostgresSpec) int32 {
 	min := c.OpConfig.MinInstances
 	max := c.OpConfig.MaxInstances
 	cur := spec.NumberOfInstances
-	newcur = cur
+	newcur := cur
 
 	if max >= 0 && newcur > max {
 		newcur = max
@@ -820,7 +820,7 @@ func (c *Cluster) getNumberOfInstances(spec *spec.PostgresSpec) (newcur int32) {
 		c.logger.Infof("adjusted number of instances from %d to %d (min: %d, max: %d)", cur, newcur, min, max)
 	}
 
-	return
+	return newcur
 }
 
 func generatePersistentVolumeClaimTemplate(volumeSize, volumeStorageClass string) (*v1.PersistentVolumeClaim, error) {
@@ -860,8 +860,8 @@ func generatePersistentVolumeClaimTemplate(volumeSize, volumeStorageClass string
 	return volumeClaim, nil
 }
 
-func (c *Cluster) generateUserSecrets() (secrets map[string]*v1.Secret) {
-	secrets = make(map[string]*v1.Secret, len(c.pgUsers))
+func (c *Cluster) generateUserSecrets() map[string]*v1.Secret {
+	secrets := make(map[string]*v1.Secret, len(c.pgUsers))
 	namespace := c.Namespace
 	for username, pgUser := range c.pgUsers {
 		//Skip users with no password i.e. human users (they'll be authenticated using pam)
@@ -878,7 +878,7 @@ func (c *Cluster) generateUserSecrets() (secrets map[string]*v1.Secret) {
 		}
 	}
 
-	return
+	return secrets
 }
 
 func (c *Cluster) generateSingleUserSecret(namespace string, pgUser spec.PgUser) *v1.Secret {

pkg/cluster/pg.go

@@ -183,32 +183,30 @@ func (c *Cluster) getDatabases() (dbs map[string]string, err error) {
 		dbs[datname] = owner
 	}
 
-	return
+	return dbs, err
 }
 
 // executeCreateDatabase creates new database with the given owner.
 // The caller is responsible for openinging and closing the database connection.
 func (c *Cluster) executeCreateDatabase(datname, owner string) error {
-	if !c.databaseNameOwnerValid(datname, owner) {
-		return nil
-	}
-	c.logger.Infof("creating database %q with owner %q", datname, owner)
-
-	if _, err := c.pgDb.Exec(fmt.Sprintf(createDatabaseSQL, datname, owner)); err != nil {
-		return fmt.Errorf("could not execute create database: %v", err)
-	}
-	return nil
+	return c.execCreateOrAlterDatabase(datname, owner, createDatabaseSQL,
+		"creating database", "create database")
 }
 
 // executeCreateDatabase changes the owner of the given database.
 // The caller is responsible for openinging and closing the database connection.
 func (c *Cluster) executeAlterDatabaseOwner(datname string, owner string) error {
+	return c.execCreateOrAlterDatabase(datname, owner, alterDatabaseOwnerSQL,
+		"changing owner for database", "alter database owner")
+}
+
+func (c *Cluster) execCreateOrAlterDatabase(datname, owner, statement, doing, operation string) error {
 	if !c.databaseNameOwnerValid(datname, owner) {
 		return nil
 	}
-	c.logger.Infof("changing database %q owner to %q", datname, owner)
-	if _, err := c.pgDb.Exec(fmt.Sprintf(alterDatabaseOwnerSQL, datname, owner)); err != nil {
-		return fmt.Errorf("could not execute alter database owner: %v", err)
+	c.logger.Infof("%s %q owner %q", doing, datname, owner)
+	if _, err := c.pgDb.Exec(fmt.Sprintf(statement, datname, owner)); err != nil {
+		return fmt.Errorf("could not execute %s: %v", operation, err)
 	}
 	return nil
 }

pkg/cluster/pod.go

@@ -183,8 +183,8 @@ func (c *Cluster) masterCandidate(oldNodeName string) (*v1.Pod, error) {
 func (c *Cluster) MigrateMasterPod(podName spec.NamespacedName) error {
 	var (
 		masterCandidatePod *v1.Pod
-		err error
-		eol bool
+		err                error
+		eol                bool
 	)
 
 	oldMaster, err := c.KubeClient.Pods(podName.Namespace).Get(podName.Name, metav1.GetOptions{})
@@ -212,7 +212,7 @@ func (c *Cluster) MigrateMasterPod(podName spec.NamespacedName) error {
 		var sset *v1beta1.StatefulSet
 		if sset, err = c.KubeClient.StatefulSets(c.Namespace).Get(c.statefulSetName(),
 			metav1.GetOptions{}); err != nil {
-				return fmt.Errorf("could not retrieve cluster statefulset: %v", err)
+			return fmt.Errorf("could not retrieve cluster statefulset: %v", err)
 		}
 		c.Statefulset = sset
 	}
@@ -225,7 +225,6 @@ func (c *Cluster) MigrateMasterPod(podName spec.NamespacedName) error {
 		c.logger.Warningf("single master pod for cluster %q, migration will cause longer downtime of the master instance", c.clusterName())
 	}
 
-
 	// there are two cases for each postgres cluster that has its master pod on the node to migrate from:
 	// - the cluster has some replicas - migrate one of those if necessary and failover to it
 	// - there are no replicas - just terminate the master and wait until it respawns

pkg/cluster/resources.go

@@ -633,27 +633,3 @@ func (c *Cluster) GetStatefulSet() *v1beta1.StatefulSet {
 func (c *Cluster) GetPodDisruptionBudget() *policybeta1.PodDisruptionBudget {
 	return c.PodDisruptionBudget
 }
-
-func (c *Cluster) createDatabases() error {
-	c.setProcessName("creating databases")
-
-	if len(c.Spec.Databases) == 0 {
-		return nil
-	}
-
-	if err := c.initDbConn(); err != nil {
-		return fmt.Errorf("could not init database connection")
-	}
-	defer func() {
-		if err := c.closeDbConn(); err != nil {
-			c.logger.Errorf("could not close database connection: %v", err)
-		}
-	}()
-
-	for datname, owner := range c.Spec.Databases {
-		if err := c.executeCreateDatabase(datname, owner); err != nil {
-			return err
-		}
-	}
-	return nil
-}

pkg/cluster/sync.go

@@ -2,11 +2,9 @@ package cluster
 
 import (
 	"fmt"
-	"reflect"
-
-	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
-	policybeta1 "k8s.io/api/policy/v1beta1"
 	"k8s.io/api/core/v1"
+	policybeta1 "k8s.io/api/policy/v1beta1"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
 
 	"github.com/zalando-incubator/postgres-operator/pkg/spec"
 	"github.com/zalando-incubator/postgres-operator/pkg/util"
@@ -17,7 +15,8 @@ import (
 
 // Sync syncs the cluster, making sure the actual Kubernetes objects correspond to what is defined in the manifest.
 // Unlike the update, sync does not error out if some objects do not exist and takes care of creating them.
-func (c *Cluster) Sync(newSpec *spec.Postgresql) (err error) {
+func (c *Cluster) Sync(newSpec *spec.Postgresql) error {
+	var err error
 	c.mu.Lock()
 	defer c.mu.Unlock()
 
@@ -34,7 +33,7 @@ func (c *Cluster) Sync(newSpec *spec.Postgresql) (err error) {
 
 	if err = c.initUsers(); err != nil {
 		err = fmt.Errorf("could not init users: %v", err)
-		return
+		return err
 	}
 
 	c.logger.Debugf("syncing secrets")
@@ -42,13 +41,13 @@ func (c *Cluster) Sync(newSpec *spec.Postgresql) (err error) {
 	//TODO: mind the secrets of the deleted/new users
 	if err = c.syncSecrets(); err != nil {
 		err = fmt.Errorf("could not sync secrets: %v", err)
-		return
+		return err
 	}
 
 	c.logger.Debugf("syncing services")
 	if err = c.syncServices(); err != nil {
 		err = fmt.Errorf("could not sync services: %v", err)
-		return
+		return err
 	}
 
 	// potentially enlarge volumes before changing the statefulset. By doing that
@@ -60,14 +59,14 @@ func (c *Cluster) Sync(newSpec *spec.Postgresql) (err error) {
 	c.logger.Debugf("syncing persistent volumes")
 	if err = c.syncVolumes(); err != nil {
 		err = fmt.Errorf("could not sync persistent volumes: %v", err)
-		return
+		return err
 	}
 
 	c.logger.Debugf("syncing statefulsets")
 	if err = c.syncStatefulSet(); err != nil {
 		if !k8sutil.ResourceAlreadyExists(err) {
 			err = fmt.Errorf("could not sync statefulsets: %v", err)
-			return
+			return err
 		}
 	}
 
@@ -76,22 +75,22 @@ func (c *Cluster) Sync(newSpec *spec.Postgresql) (err error) {
 		c.logger.Debugf("syncing roles")
 		if err = c.syncRoles(); err != nil {
 			err = fmt.Errorf("could not sync roles: %v", err)
-			return
+			return err
 		}
 		c.logger.Debugf("syncing databases")
 		if err = c.syncDatabases(); err != nil {
 			err = fmt.Errorf("could not sync databases: %v", err)
-			return
+			return err
 		}
 	}
 
 	c.logger.Debug("syncing pod disruption budgets")
 	if err = c.syncPodDisruptionBudget(false); err != nil {
 		err = fmt.Errorf("could not sync pod disruption budget: %v", err)
-		return
+		return err
 	}
 
-	return
+	return err
 }
 
 func (c *Cluster) syncServices() error {
@@ -153,7 +152,7 @@ func (c *Cluster) syncService(role PostgresRole) error {
 
 func (c *Cluster) syncEndpoint(role PostgresRole) error {
 	var (
-		ep *v1.Endpoints
+		ep  *v1.Endpoints
 		err error
 	)
 	c.setProcessName("syncing %s endpoint", role)
@@ -187,8 +186,8 @@ func (c *Cluster) syncEndpoint(role PostgresRole) error {
 
 func (c *Cluster) syncPodDisruptionBudget(isUpdate bool) error {
 	var (
-		pdb   *policybeta1.PodDisruptionBudget
-		err   error
+		pdb *policybeta1.PodDisruptionBudget
+		err error
 	)
 	if pdb, err = c.KubeClient.PodDisruptionBudgets(c.Namespace).Get(c.podDisruptionBudgetName(), metav1.GetOptions{}); err == nil {
 		c.PodDisruptionBudget = pdb
@@ -257,7 +256,9 @@ func (c *Cluster) syncStatefulSet() error {
 		podsRollingUpdateRequired = (len(pods) > 0)
 		if podsRollingUpdateRequired {
 			c.logger.Warningf("found pods from the previous statefulset: trigger rolling update")
-			c.applyRollingUpdateFlagforStatefulSet(podsRollingUpdateRequired)
+			if err := c.applyRollingUpdateFlagforStatefulSet(podsRollingUpdateRequired); err != nil {
+				return fmt.Errorf("could not set rolling update flag for the statefulset: %v", err)
+			}
 		}
 		c.logger.Infof("created missing statefulset %q", util.NameFromMeta(sset.ObjectMeta))
 
@@ -318,7 +319,7 @@ func (c *Cluster) syncStatefulSet() error {
 // (like max_connections) has changed and if necessary sets it via the Patroni API
 func (c *Cluster) checkAndSetGlobalPostgreSQLConfiguration() error {
 	var (
-		err error
+		err  error
 		pods []v1.Pod
 	)
 
@@ -394,7 +395,7 @@ func (c *Cluster) syncSecrets() error {
 			// if this secret belongs to the infrastructure role and the password has changed - replace it in the secret
 			if pwdUser.Password != string(secret.Data["password"]) && pwdUser.Origin == spec.RoleOriginInfrastructure {
 				c.logger.Debugf("updating the secret %q from the infrastructure roles", secretSpec.Name)
-				if secret, err = c.KubeClient.Secrets(secretSpec.Namespace).Update(secretSpec); err != nil {
+				if _, err = c.KubeClient.Secrets(secretSpec.Namespace).Update(secretSpec); err != nil {
 					return fmt.Errorf("could not update infrastructure role secret for role %q: %v", secretUsername, err)
 				}
 			} else {
@@ -469,15 +470,6 @@ func (c *Cluster) syncVolumes() error {
 	return nil
 }
 
-func (c *Cluster) samePDBWith(pdb *policybeta1.PodDisruptionBudget) (match bool, reason string) {
-	match = reflect.DeepEqual(pdb.Spec, c.PodDisruptionBudget.Spec)
-	if !match {
-		reason = "new service spec doesn't match the current one"
-	}
-
-	return
-}
-
 func (c *Cluster) syncDatabases() error {
 	c.setProcessName("syncing databases")