Add support for keeping a range of snapshots

cmd/restic/cmd_forget.go

@@ -5,7 +5,6 @@ import (
 	"encoding/json"
 	"sort"
 	"strings"
-	"time"
 
 	"github.com/restic/restic/internal/errors"
 	"github.com/restic/restic/internal/restic"
@@ -34,7 +33,7 @@ type ForgetOptions struct {
 	Weekly     int
 	Monthly    int
 	Yearly     int
-	NewerThan time.Duration
+	WithinDays int
 	KeepTags   restic.TagLists
 
 	Host    string
@@ -60,7 +59,7 @@ func init() {
 	f.IntVarP(&forgetOptions.Weekly, "keep-weekly", "w", 0, "keep the last `n` weekly snapshots")
 	f.IntVarP(&forgetOptions.Monthly, "keep-monthly", "m", 0, "keep the last `n` monthly snapshots")
 	f.IntVarP(&forgetOptions.Yearly, "keep-yearly", "y", 0, "keep the last `n` yearly snapshots")
-	f.DurationVar(&forgetOptions.NewerThan, "keep-newer-than", 0, "keep snapshots that were created within this timeframe")
+	f.IntVar(&forgetOptions.WithinDays, "keep-within", 0, "keep snapshots that were created within `days` before the newest")
 
 	f.Var(&forgetOptions.KeepTags, "keep-tag", "keep snapshots with this `taglist` (can be specified multiple times)")
 	// Sadly the commonly used shortcut `H` is already used.
@@ -166,11 +165,6 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		}
 	}
 
-	var ageCutoff time.Time
-	if opts.NewerThan > 0 {
-		ageCutoff = time.Now().Add(-opts.NewerThan)
-	}
-
 	policy := restic.ExpirePolicy{
 		Last:    opts.Last,
 		Hourly:  opts.Hourly,
@@ -178,7 +172,7 @@ func runForget(opts ForgetOptions, gopts GlobalOptions, args []string) error {
 		Weekly:  opts.Weekly,
 		Monthly: opts.Monthly,
 		Yearly:  opts.Yearly,
-		NewerThan: ageCutoff,
+		Within:  opts.WithinDays,
 		Tags:    opts.KeepTags,
 	}
 

internal/restic/snapshot_policy.go

@@ -16,7 +16,7 @@ type ExpirePolicy struct {
 	Weekly  int       // keep the last n weekly snapshots
 	Monthly int       // keep the last n monthly snapshots
 	Yearly  int       // keep the last n yearly snapshots
-	NewerThan time.Time // keep snapshots newer than this time
+	Within  int       // keep snapshots made within this number of days since the newest snapshot
 	Tags    []TagList // keep all snapshots that include at least one of the tag lists.
 }
 
@@ -40,8 +40,8 @@ func (e ExpirePolicy) String() (s string) {
 	if e.Yearly > 0 {
 		keeps = append(keeps, fmt.Sprintf("%d yearly", e.Yearly))
 	}
-	if !e.NewerThan.IsZero() {
+	if e.Within != 0 {
-		keeps = append(keeps, fmt.Sprintf("snapshots newer than %s", e.NewerThan))
+		keeps = append(keeps, fmt.Sprintf("snapshots within %d days of the newest snapshot", e.Within))
 	}
 
 	return fmt.Sprintf("keep the last %s snapshots", strings.Join(keeps, ", "))
@@ -94,6 +94,22 @@ func always(d time.Time, nr int) int {
 	return nr
 }
 
+// findLatestTimestamp returns the time stamp for the newest snapshot.
+func findLatestTimestamp(list Snapshots) time.Time {
+	if len(list) == 0 {
+		panic("list of snapshots is empty")
+	}
+
+	var latest time.Time
+	for _, sn := range list {
+		if sn.Time.After(latest) {
+			latest = sn.Time
+		}
+	}
+
+	return latest
+}
+
 // ApplyPolicy returns the snapshots from list that are to be kept and removed
 // according to the policy p. list is sorted in the process.
 func ApplyPolicy(list Snapshots, p ExpirePolicy) (keep, remove Snapshots) {
@@ -120,6 +136,8 @@ func ApplyPolicy(list Snapshots, p ExpirePolicy) (keep, remove Snapshots) {
 		{p.Yearly, y, -1},
 	}
 
+	latest := findLatestTimestamp(list)
+
 	for nr, cur := range list {
 		var keepSnap bool
 
@@ -130,10 +148,13 @@ func ApplyPolicy(list Snapshots, p ExpirePolicy) (keep, remove Snapshots) {
 			}
 		}
 
-		// If a timestamp is specified, it's a hard cutoff for older snapshots.
+		// If the timestamp of the snapshot is within the range, then keep it.
-		if !p.NewerThan.IsZero() && cur.Time.After(p.NewerThan) {
+		if p.Within != 0 {
+			t := latest.AddDate(0, 0, -p.Within)
+			if cur.Time.After(t) {
 				keepSnap = true
 			}
+		}
 
 		// Now update the other buckets and see if they have some counts left.
 		for i, b := range buckets {

internal/restic/snapshot_policy_test.go

@@ -21,6 +21,15 @@ func parseTimeUTC(s string) time.Time {
 	return t.UTC()
 }
 
+func parseDuration(s string) time.Duration {
+	d, err := time.ParseDuration(s)
+	if err != nil {
+		panic(err)
+	}
+
+	return d
+}
+
 func TestExpireSnapshotOps(t *testing.T) {
 	data := []struct {
 		expectEmpty bool
@@ -171,7 +180,10 @@ var expireTests = []restic.ExpirePolicy{
 	{Tags: []restic.TagList{{"foo"}}},
 	{Tags: []restic.TagList{{"foo", "bar"}}},
 	{Tags: []restic.TagList{{"foo"}, {"bar"}}},
-	{NewerThan: parseTimeUTC("2016-01-01 01:00:00")},
+	{Within: 1},
+	{Within: 2},
+	{Within: 7},
+	{Within: 30},
 }
 
 func TestApplyPolicy(t *testing.T) {

internal/restic/testdata/policy_keep_snapshots_21

@@ -3,95 +3,5 @@
     "time": "2016-01-18T12:02:03Z",
     "tree": null,
     "paths": null
-  },
-  {
-    "time": "2016-01-12T21:08:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-12T21:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-09T21:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-08T20:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-07T10:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-06T08:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-05T09:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T16:23:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T12:30:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T12:28:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T12:24:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T12:23:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T11:23:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-04T10:23:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-03T07:02:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-01T07:08:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-01T01:03:03Z",
-    "tree": null,
-    "paths": null
-  },
-  {
-    "time": "2016-01-01T01:02:03Z",
-    "tree": null,
-    "paths": null
   }
 ]

internal/restic/testdata/policy_keep_snapshots_22

@@ -0,0 +1,7 @@
+[
+  {
+    "time": "2016-01-18T12:02:03Z",
+    "tree": null,
+    "paths": null
+  }
+]

internal/restic/testdata/policy_keep_snapshots_23

@@ -0,0 +1,17 @@
+[
+  {
+    "time": "2016-01-18T12:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-12T21:08:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-12T21:02:03Z",
+    "tree": null,
+    "paths": null
+  }
+]

internal/restic/testdata/policy_keep_snapshots_24

@@ -0,0 +1,97 @@
+[
+  {
+    "time": "2016-01-18T12:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-12T21:08:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-12T21:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-09T21:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-08T20:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-07T10:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-06T08:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-05T09:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T16:23:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T12:30:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T12:28:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T12:24:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T12:23:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T11:23:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-04T10:23:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-03T07:02:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-01T07:08:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-01T01:03:03Z",
+    "tree": null,
+    "paths": null
+  },
+  {
+    "time": "2016-01-01T01:02:03Z",
+    "tree": null,
+    "paths": null
+  }
+]