Check error and use Ping in db.Open (#37)

There was a missing error check and the connection was checked before
breaking out of the backoff loop.

Author: rdner

go.mod

@@ -4,7 +4,7 @@ require (
 	github.com/Masterminds/squirrel v1.1.0
 	github.com/asaskevich/govalidator v0.0.0-20190424111038-f61b66f89f4a // indirect
 	github.com/bakins/net-http-recover v0.0.0-20141007104922-6cba69d01459
-	github.com/cenkalti/backoff v2.2.1+incompatible
+	github.com/cenkalti/backoff/v4 v4.0.0
 	github.com/contiamo/goserver v0.5.0
 	github.com/contiamo/jwt v0.2.2
 	github.com/dgrijalva/jwt-go v3.2.0+incompatible

go.sum

@@ -13,8 +13,8 @@ github.com/beorn7/perks v0.0.0-20180321164747-3a771d992973/go.mod h1:Dwedo/Wpr24
 github.com/beorn7/perks v1.0.0/go.mod h1:KWe93zE9D1o94FZ5RNwFwVgaQK1VOXiVxmqh+CedLV8=
 github.com/beorn7/perks v1.0.1 h1:VlbKKnNfV8bJzeqoa4cOKqO6bYr3WgKZxO8Z16+hsOM=
 github.com/beorn7/perks v1.0.1/go.mod h1:G2ZrVWU2WbWT9wwq4/hrbKbnv/1ERSJQ0ibhJ6rlkpw=
-github.com/cenkalti/backoff v2.2.1+incompatible h1:tNowT99t7UNflLxfYYSlKYsBpXdEet03Pg2g16Swow4=
-github.com/cenkalti/backoff v2.2.1+incompatible/go.mod h1:90ReRw6GdpyfrHakVjL/QHaoyV4aDUVVkXQJJJ3NXXM=
+github.com/cenkalti/backoff/v4 v4.0.0 h1:6VeaLF9aI+MAUQ95106HwWzYZgJJpZ4stumjj6RFYAU=
+github.com/cenkalti/backoff/v4 v4.0.0/go.mod h1:eEew/i+1Q6OrCDZh3WiXYv3+nJwBASZ8Bog/87DQnVg=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd h1:qMd81Ts1T2OTKmB4acZcyKaMtRnY5Y44NuXGX2GFJ1w=
 github.com/codahale/hdrhistogram v0.0.0-20161010025455-3a0bb77429bd/go.mod h1:sE/e/2PUdi/liOCUjSTXgM1o87ZssimdTWN964YiIeI=

pkg/db/open.go

@@ -4,14 +4,17 @@ import (
 	"context"
 	"database/sql"
 
-	"github.com/cenkalti/backoff"
+	"github.com/cenkalti/backoff/v4"
 	"github.com/contiamo/go-base/pkg/config"
 )
 
 // Open opens a connection to a database and retries until ctx.Done()
 // The users must import all the necessary drivers before calling this function.
 func Open(ctx context.Context, cfg config.Database) (db *sql.DB, err error) {
 	connStr, err := cfg.GetConnectionString()
+	if err != nil {
+		return nil, err
+	}
 
 	err = backoff.Retry(func() error {
 		select {
@@ -22,7 +25,11 @@ func Open(ctx context.Context, cfg config.Database) (db *sql.DB, err error) {
 		default:
 			{
 				db, err = sql.Open(cfg.DriverName, connStr)
-				return err
+				if err != nil {
+					return err
+				}
+
+				return db.Ping()
 			}
 		}
 	}, backoff.NewExponentialBackOff())