enhance: surface redis ping errors (#1165)

queue/redis/ping.go

@@ -4,7 +4,6 @@ package redis
 
 import (
 	"context"
-	"fmt"
 )
 
 // Ping contacts the queue to test its connection.
@@ -13,7 +12,7 @@ func (c *client) Ping(ctx context.Context) error {
 	err := c.Redis.Ping(ctx).Err()
 	if err != nil {
 		c.Logger.Debugf("unable to ping Redis queue.")
-		return fmt.Errorf("unable to establish connection to Redis queue")
+		return err
 	}
 
 	return nil

queue/redis/redis.go

@@ -9,6 +9,7 @@ import (
 	"time"
 
 	"github.com/alicebob/miniredis/v2"
+	"github.com/pkg/errors"
 	"github.com/redis/go-redis/v9"
 	"github.com/sirupsen/logrus"
 
@@ -151,9 +152,10 @@ func failoverFromOptions(source *redis.Options) *redis.FailoverOptions {
 // we try to set it up.
 func pingQueue(c *client) error {
 	// attempt 10 times
+	var err error
 	for i := 0; i < 10; i++ {
 		// send ping request to client
-		err := c.Redis.Ping(context.Background()).Err()
+		err = c.Redis.Ping(context.Background()).Err()
 		if err != nil {
 			c.Logger.Debugf("unable to ping Redis queue. Retrying in %v", time.Duration(i)*time.Second)
 			time.Sleep(1 * time.Second)
@@ -164,7 +166,8 @@ func pingQueue(c *client) error {
 		return nil
 	}
 
-	return fmt.Errorf("unable to establish connection to Redis queue")
+	// capture last seen non-nil error
+	return errors.Wrap(err, "unable to establish connection to Redis queue")
 }
 
 // NewTest returns a Queue implementation that