Address feedback

Set default numberOfInstances to 2. Add verifications for config. Fix
schema/user typos. Avoid closing an empty connections.

pkg/cluster/database.go

@@ -44,7 +44,7 @@ const (
 		$$ LANGUAGE plpgsql SECURITY DEFINER;
 
 		REVOKE ALL ON FUNCTION {{.pool_schema}}.user_lookup(text)
-			FROM public, {{.pool_schema}};
+			FROM public, {{.pool_user}};
 		GRANT EXECUTE ON FUNCTION {{.pool_schema}}.user_lookup(text)
 			TO {{.pool_user}};
 		GRANT USAGE ON SCHEMA {{.pool_schema}} TO {{.pool_user}};
@@ -124,6 +124,10 @@ func (c *Cluster) initDbConnWithName(dbname string) error {
 	return nil
 }
 
+func (c *Cluster) connectionIsClosed() bool {
+	return c.pgDb == nil
+}
+
 func (c *Cluster) closeDbConn() (err error) {
 	c.setProcessName("closing db connection")
 	if c.pgDb != nil {
@@ -284,8 +288,10 @@ func (c *Cluster) installLookupFunction(poolSchema, poolUser string) error {
 		return fmt.Errorf("could not init database connection")
 	}
 	defer func() {
-		// in case if everything went fine this can generate a warning about
-		// trying to close an empty connection.
+		if c.connectionIsClosed() {
+			return
+		}
+
 		if err := c.closeDbConn(); err != nil {
 			c.logger.Errorf("could not close database connection: %v", err)
 		}
@@ -300,8 +306,12 @@ func (c *Cluster) installLookupFunction(poolSchema, poolUser string) error {
 	templater := template.Must(template.New("sql").Parse(connectionPoolLookup))
 
 	for dbname, _ := range currentDatabases {
+		if dbname == "template0" || dbname == "template1" {
+			continue
+		}
+
 		if err := c.initDbConnWithName(dbname); err != nil {
-			return fmt.Errorf("could not init database connection")
+			return fmt.Errorf("could not init database connection to %s", dbname)
 		}
 
 		c.logger.Infof("Install pool lookup function into %s", dbname)
@@ -312,8 +322,10 @@ func (c *Cluster) installLookupFunction(poolSchema, poolUser string) error {
 		}
 
 		if err := templater.Execute(&stmtBytes, params); err != nil {
-			return fmt.Errorf("could not prepare sql statement %+v: %v",
+			c.logger.Errorf("could not prepare sql statement %+v: %v",
 				params, err)
+			// process other databases
+			continue
 		}
 
 		// golang sql will do retries couple of times if pq driver reports
@@ -335,8 +347,10 @@ func (c *Cluster) installLookupFunction(poolSchema, poolUser string) error {
 			})
 
 		if execErr != nil {
-			return fmt.Errorf("could not execute after retries %s: %v",
+			c.logger.Errorf("could not execute after retries %s: %v",
 				stmtBytes.String(), err)
+			// process other databases
+			continue
 		}
 
 		c.logger.Infof("Pool lookup function installed into %s", dbname)

pkg/cluster/sync.go

@@ -645,7 +645,7 @@ func (c *Cluster) syncConnectionPool(oldSpec, newSpec *acidv1.Postgresql, lookup
 
 			if newConnPool != nil {
 				specSchema = newConnPool.Schema
-				specUser = newConnPool.Schema
+				specUser = newConnPool.User
 			}
 
 			schema := util.Coalesce(
@@ -656,7 +656,9 @@ func (c *Cluster) syncConnectionPool(oldSpec, newSpec *acidv1.Postgresql, lookup
 				specUser,
 				c.OpConfig.ConnectionPool.User)
 
-			lookup(schema, user)
+			if err := lookup(schema, user); err != nil {
+				return err
+			}
 		}
 
 		if err := c.syncConnectionPoolWorker(oldSpec, newSpec); err != nil {

pkg/controller/operator_config.go

@@ -152,11 +152,11 @@ func (c *Controller) importConfigurationFromCRD(fromCRD *acidv1.OperatorConfigur
 	// so ensure default values here.
 	result.ConnectionPool.NumberOfInstances = util.CoalesceInt32(
 		fromCRD.ConnectionPool.NumberOfInstances,
-		int32ToPointer(1))
+		int32ToPointer(2))
 
 	result.ConnectionPool.NumberOfInstances = util.MaxInt32(
 		result.ConnectionPool.NumberOfInstances,
-		int32ToPointer(1))
+		int32ToPointer(2))
 
 	result.ConnectionPool.Schema = util.Coalesce(
 		fromCRD.ConnectionPool.Schema,

pkg/util/config/config.go

@@ -8,6 +8,7 @@ import (
 	"fmt"
 
 	"github.com/zalando/postgres-operator/pkg/spec"
+	"github.com/zalando/postgres-operator/pkg/util/constants"
 )
 
 // CRD describes CustomResourceDefinition specific configuration parameters
@@ -211,5 +212,10 @@ func validate(cfg *Config) (err error) {
 	if cfg.Workers == 0 {
 		err = fmt.Errorf("number of workers should be higher than 0")
 	}
+
+	if *cfg.ConnectionPool.NumberOfInstances < constants.ConnPoolMinInstances {
+		msg := "number of connection pool instances should be higher than %d"
+		err = fmt.Errorf(msg, constants.ConnPoolMinInstances)
+	}
 	return
 }