feat: add backup purging

Author: vlourme

README.md

@@ -45,6 +45,7 @@ Optional args:
 - `--delete`: delete the `backup` folder after upload. This requires `rw` permission on the volume.
 - `--replace`: always save into the same prefix, replacing the previous uploaded backup.
 - `--compress`: use zstd to compress files before uploading.
+- `--purge [days]`: purge older backups after defined days.
 
 ## Restore a backup
 

schedule.go

@@ -5,14 +5,18 @@ import (
 	"fmt"
 	"log"
 	"path"
+	"strings"
 	"time"
 
 	"github.com/aws/aws-sdk-go-v2/service/s3"
+	s3types "github.com/aws/aws-sdk-go-v2/service/s3/types"
 	"github.com/redis/go-redis/v9"
 	"github.com/robfig/cron/v3"
 	"github.com/urfave/cli/v3"
 )
 
+const BACKUP_FORMAT = "2006-01-02_15-04-05"
+
 var ScheduleCmd = &cli.Command{
 	Name:  "schedule",
 	Usage: "Execute backup on a schedule",
@@ -35,6 +39,10 @@ var ScheduleCmd = &cli.Command{
 			Name:  "compress",
 			Usage: "Compress files using Zstd",
 		},
+		&cli.IntFlag{
+			Name:  "purge",
+			Usage: "Purge backup older than defined number of days",
+		},
 	},
 	Action: func(ctx context.Context, c *cli.Command) error {
 		s3client := ctx.Value("s3client").(*s3.Client)
@@ -44,7 +52,7 @@ var ScheduleCmd = &cli.Command{
 		_, err := scheduler.AddFunc(c.StringArg("cron"), func() {
 			prefix := c.String("prefix")
 			if !c.Bool("replace") {
-				date := time.Now().Format("2006-01-02_15-04-05")
+				date := time.Now().Format(BACKUP_FORMAT)
 				prefix = path.Join(prefix, date)
 			}
 
@@ -65,9 +73,93 @@ var ScheduleCmd = &cli.Command{
 			return fmt.Errorf("cannot register scheduler: %s", err)
 		}
 
+		if c.IsSet("purge") {
+			scheduler.AddFunc("0 * * * *", func() {
+				purgeBackups(s3client, c.String("bucket"), c.String("prefix"), c.Int("purge"))
+			})
+		}
+
 		log.Println("Start scheduler")
 		scheduler.Run()
 
 		return nil
 	},
 }
+
+func purgeBackups(s3client *s3.Client, bucket, prefix string, day int) error {
+	prefixWithSuffix := prefix
+	if !strings.HasSuffix(prefixWithSuffix, "/") {
+		prefixWithSuffix += "/"
+	}
+
+	paginator := s3.NewListObjectsV2Paginator(s3client, &s3.ListObjectsV2Input{
+		Bucket:    new(bucket),
+		Prefix:    new(prefixWithSuffix),
+		Delimiter: new("/"),
+	})
+	ctx := context.Background()
+	limit := time.Now().Add(-time.Duration(day) * time.Hour * 24)
+
+	for paginator.HasMorePages() {
+		page, err := paginator.NextPage(ctx)
+		if err != nil {
+			return fmt.Errorf("cannot paginate s3: %w", err)
+		}
+
+		for _, obj := range page.CommonPrefixes {
+			pf := path.Base(*obj.Prefix)
+			ts, err := time.Parse(BACKUP_FORMAT, pf)
+			if err != nil {
+				return fmt.Errorf("cannot parse time: %w", err)
+			}
+
+			if ts.Before(limit) {
+				if err := deletePrefix(ctx, s3client, bucket, prefixWithSuffix+pf); err != nil {
+					return fmt.Errorf("cannot delete backup: %w", err)
+				}
+			}
+		}
+	}
+
+	return nil
+}
+
+func deletePrefix(ctx context.Context, client *s3.Client, bucket, prefix string) error {
+	paginator := s3.NewListObjectsV2Paginator(client, &s3.ListObjectsV2Input{
+		Bucket: new(bucket),
+		Prefix: new(prefix),
+	})
+
+	for paginator.HasMorePages() {
+		page, err := paginator.NextPage(ctx)
+		if err != nil {
+			return err
+		}
+
+		if len(page.Contents) == 0 {
+			continue
+		}
+
+		objects := make([]s3types.ObjectIdentifier, 0, len(page.Contents))
+
+		for _, obj := range page.Contents {
+			objects = append(objects, s3types.ObjectIdentifier{
+				Key: obj.Key,
+			})
+		}
+
+		_, err = client.DeleteObjects(ctx, &s3.DeleteObjectsInput{
+			Bucket: new(bucket),
+			Delete: &s3types.Delete{
+				Objects: objects,
+				Quiet:   new(true),
+			},
+		})
+		if err != nil {
+			return err
+		}
+	}
+
+	log.Println("Purged old backup:", prefix)
+	return nil
+}