From 4bffc9e92a587ac4e56cdb4fdb28e15a25e8e497 Mon Sep 17 00:00:00 2001
From: Tom Wiesing <tkw01536@gmail.com>
Date: Thu, 8 Sep 2022 14:31:51 +0200
Subject: [PATCH] backup: Prune old backups

This commit updates the backup command to prune old backups.
---
 cmd/backup.go             |  7 +++++++
 env/backup.go             | 44 +++++++++++++++++++++++++++++++++++++++
 internal/config/config.go |  2 +-
 3 files changed, 52 insertions(+), 1 deletion(-)

diff --git a/cmd/backup.go b/cmd/backup.go
index 44d164d..a31f468 100644
--- a/cmd/backup.go
+++ b/cmd/backup.go
@@ -15,6 +15,7 @@ import (
 var Backup wisski_distillery.Command = backup{}
 
 type backup struct {
+	NoPrune     bool `short:"no" long:"no-prune" description:"Do not prune older backup archives"`
 	StagingOnly bool `short:"s" long:"staging-only" description:"Do not package into a backup archive, but only create a staging directory"`
 	Positionals struct {
 		Dest string `positional-arg-name:"DEST" description:"Destination path to write backup archive to. Defaults to the snapshots/archives/ directory"`
@@ -40,6 +41,12 @@ func (bk backup) Run(context wisski_distillery.Context) error {
 	dis := context.Environment
 	var err error
 
+	if !bk.NoPrune {
+		defer logging.LogOperation(func() error {
+			return dis.PruneBackups(context.IOStream)
+		}, context.IOStream, "Pruning old backups")
+	}
+
 	// determine the target path for the archive
 	var sPath string
 	if !bk.StagingOnly {
diff --git a/env/backup.go b/env/backup.go
index 14270b2..a75df8c 100644
--- a/env/backup.go
+++ b/env/backup.go
@@ -6,6 +6,7 @@ import (
 	"os"
 	"path/filepath"
 	"sync"
+	"time"
 
 	"github.com/FAU-CDI/wisski-distillery/internal/fsx"
 	"github.com/FAU-CDI/wisski-distillery/internal/logging"
@@ -187,3 +188,46 @@ func (backup Backup) WriteReport(io stream.IOStream) error {
 		return err
 	}, io, "Writing backup report")
 }
+
+// ShouldPrune determines if a file with the provided modtime
+func (dis *Distillery) ShouldPrune(modtime time.Time) bool {
+	return time.Since(modtime) > time.Duration(dis.Config.MaxBackupAge)*24*time.Hour
+}
+
+// PruneBackups prunes all backups older than the maximum backup age
+func (dis *Distillery) PruneBackups(io stream.IOStream) error {
+	sPath := dis.SnapshotsArchivePath()
+
+	// list all the files
+	entries, err := os.ReadDir(sPath)
+	if err != nil {
+		return err
+	}
+
+	for _, entry := range entries {
+		// skip directories
+		if entry.IsDir() {
+			continue
+		}
+
+		// grab info about the file
+		info, err := entry.Info()
+		if err != nil {
+			return err
+		}
+
+		// check if it should be pruned!
+		if !dis.ShouldPrune(info.ModTime()) {
+			continue
+		}
+
+		// assemble path, and then remove the file!
+		path := filepath.Join(sPath, entry.Name())
+		io.Printf("Removing %s cause it is older than %d days", path, dis.Config.MaxBackupAge)
+
+		if err := os.Remove(path); err != nil {
+			return err
+		}
+	}
+	return nil
+}
diff --git a/internal/config/config.go b/internal/config/config.go
index f2067c1..5caff52 100644
--- a/internal/config/config.go
+++ b/internal/config/config.go
@@ -39,7 +39,7 @@ type Config struct {
 	// This email address can be configured here.
 	CertbotEmail string `env:"CERTBOT_EMAIL" default:"" validator:"is_valid_email"`
 
-	// Maximum age for backup
+	// Maximum age for backup in days
 	MaxBackupAge int `env:"MAX_BACKUP_AGE" default:"" validator:"is_valid_number"`
 
 	// Each Drupal instance requires a corresponding system user, database users and databases.