refactor: Replace lib/pq with pgx in postgresql_scaler.go

The development of `lib/pq` is over and the library doesn't receive any fixes
or new features. This is sad because nowadays `lib/pq` lacks a of lot of
features we are get used to in the C version of `libpq` and its derivatives.

I've experienced troubles with this unimplemented stuff in `lib/pq`:
- Multi-host connection, which is important for a high availability
- Support of parsing CA certificate of PostgreSQL server stored in
a `~/.postgresql` folder that led to a negative user experience

I believe there are more missing features.

These things will be never fixed in `lib/pq`, so in this patch, we replace the
abandoned `lib/pq` with an actively developing `pgx`.

Signed-off-by: Alexander Narsudinov <a-narsudinov@gmail.com>

go.mod

@@ -42,8 +42,8 @@ require (
 	github.com/hashicorp/vault/api v1.9.2
 	github.com/imdario/mergo v0.3.16
 	github.com/influxdata/influxdb-client-go/v2 v2.12.3
+	github.com/jackc/pgx/v5 v5.4.0
 	github.com/joho/godotenv v1.5.1
-	github.com/lib/pq v1.10.9
 	github.com/microsoft/ApplicationInsights-Go v0.4.4
 	github.com/microsoft/azure-devops-go-api/azuredevops v1.0.0-b5
 	github.com/mitchellh/hashstructure v1.1.0
@@ -212,6 +212,8 @@ require (
 	github.com/hashicorp/hcl v1.0.0 // indirect
 	github.com/inconshreveable/mousetrap v1.1.0 // indirect
 	github.com/influxdata/line-protocol v0.0.0-20210922203350-b1ad95c89adf // indirect
+	github.com/jackc/pgpassfile v1.0.0 // indirect
+	github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a // indirect
 	github.com/jcmturner/aescts/v2 v2.0.0 // indirect
 	github.com/jcmturner/dnsutils/v2 v2.0.0 // indirect
 	github.com/jcmturner/gofork v1.7.6 // indirect

go.sum

@@ -471,6 +471,12 @@ github.com/influxdata/influxdb-client-go/v2 v2.12.3 h1:28nRlNMRIV4QbtIUvxhWqaxn0
 github.com/influxdata/influxdb-client-go/v2 v2.12.3/go.mod h1:IrrLUbCjjfkmRuaCiGQg4m2GbkaeJDcuWoxiWdQEbA0=
 github.com/influxdata/line-protocol v0.0.0-20210922203350-b1ad95c89adf h1:7JTmneyiNEwVBOHSjoMxiWAqB992atOeepeFYegn5RU=
 github.com/influxdata/line-protocol v0.0.0-20210922203350-b1ad95c89adf/go.mod h1:xaLFMmpvUxqXtVkUJfg9QmT88cDaCJ3ZKgdZ78oO8Qo=
+github.com/jackc/pgpassfile v1.0.0 h1:/6Hmqy13Ss2zCq62VdNG8tM1wchn8zjSGOBJ6icpsIM=
+github.com/jackc/pgpassfile v1.0.0/go.mod h1:CEx0iS5ambNFdcRtxPj5JhEz+xB6uRky5eyVu/W2HEg=
+github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a h1:bbPeKD0xmW/Y25WS6cokEszi5g+S0QxI/d45PkRi7Nk=
+github.com/jackc/pgservicefile v0.0.0-20221227161230-091c0ba34f0a/go.mod h1:5TJZWKEWniPve33vlWYSoGYefn3gLQRzjfDlhSJ9ZKM=
+github.com/jackc/pgx/v5 v5.4.0 h1:BSr+GCm4N6QcgIwv0DyTFHK9ugfEFF9DzSbbzxOiXU0=
+github.com/jackc/pgx/v5 v5.4.0/go.mod h1:q6iHT8uDNXWiFNOlRqJzBTaSH3+2xCXkokxHZC5qWFY=
 github.com/jcmturner/aescts/v2 v2.0.0 h1:9YKLH6ey7H4eDBXW8khjYslgyqG2xZikXP0EQFKrle8=
 github.com/jcmturner/aescts/v2 v2.0.0/go.mod h1:AiaICIRyfYg35RUkr8yESTqvSy7csK90qZ5xfvvsoNs=
 github.com/jcmturner/dnsutils/v2 v2.0.0 h1:lltnkeZGL0wILNvrNiVCR6Ro5PGU/SeBvVO/8c/iPbo=
@@ -525,8 +531,6 @@ github.com/labstack/gommon v0.3.0/go.mod h1:MULnywXg0yavhxWKc+lOruYdAhDwPK9wf0OL
 github.com/labstack/gommon v0.4.0/go.mod h1:uW6kP17uPlLJsD3ijUYn3/M5bAxtlZhMI6m3MFxTMTM=
 github.com/leodido/go-urn v1.2.4 h1:XlAE/cm/ms7TE/VMVoduSpNBoyc2dOxHs5MZSwAN63Q=
 github.com/leodido/go-urn v1.2.4/go.mod h1:7ZrI8mTSeBSHl/UaRyKQW1qZeMgak41ANeCNaVckg+4=
-github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
-github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=
 github.com/mailru/easyjson v0.7.7 h1:UGYAvKxe3sBsEDzO8ZeWOSlIQfWFlxbzLZe7hwFURr0=
 github.com/mailru/easyjson v0.7.7/go.mod h1:xzfreul335JAWq5oZzymOObrkdz5UnU4kGfJJLY9Nlc=
 github.com/mattn/go-colorable v0.0.9/go.mod h1:9vuHe8Xs5qXnSaW/c/ABM9alt+Vo+STaOChaDxuIBZU=

pkg/scalers/postgresql_scaler.go

@@ -9,7 +9,7 @@ import (
 
 	"github.com/go-logr/logr"
 	// PostreSQL drive required for this scaler
-	_ "github.com/lib/pq"
+	_ "github.com/jackc/pgx/v5/stdlib"
 	v2 "k8s.io/api/autoscaling/v2"
 	"k8s.io/metrics/pkg/apis/external_metrics"
 
@@ -146,7 +146,7 @@ func parsePostgreSQLMetadata(config *ScalerConfig) (*postgreSQLMetadata, error)
 }
 
 func getConnection(meta *postgreSQLMetadata, logger logr.Logger) (*sql.DB, error) {
-	db, err := sql.Open("postgres", meta.connection)
+	db, err := sql.Open("pgx", meta.connection)
 	if err != nil {
 		logger.Error(err, fmt.Sprintf("Found error opening postgreSQL: %s", err))
 		return nil, err