fix: migrate prune policy options to oneof

internal/config/migrations/001prunepolicy.go

@@ -0,0 +1,41 @@
+package migrations
+
+import v1 "github.com/garethgeorge/backrest/gen/go/v1"
+
+func migration001PrunePolicy(config *v1.Config) {
+	// loop over plans and examine prune policy's
+	for _, plan := range config.Plans {
+		policy := plan.GetRetention()
+		if policy == nil {
+			continue
+		}
+
+		if policy.Policy != nil {
+			continue // already migrated
+		}
+
+		if policy.KeepLastN != 0 {
+			plan.Retention = &v1.RetentionPolicy{
+				Policy: &v1.RetentionPolicy_PolicyKeepLastN{
+					PolicyKeepLastN: policy.KeepLastN,
+				},
+			}
+		} else if policy.KeepDaily != 0 || policy.KeepHourly != 0 || policy.KeepMonthly != 0 || policy.KeepWeekly != 0 || policy.KeepYearly != 0 {
+			plan.Retention = &v1.RetentionPolicy{
+				Policy: &v1.RetentionPolicy_PolicyTimeBucketed{
+					PolicyTimeBucketed: &v1.RetentionPolicy_TimeBucketedCounts{
+						Hourly:  policy.KeepHourly,
+						Daily:   policy.KeepDaily,
+						Weekly:  policy.KeepWeekly,
+						Monthly: policy.KeepMonthly,
+						Yearly:  policy.KeepYearly,
+					},
+				},
+			}
+		} else {
+			policy.Policy = &v1.RetentionPolicy_PolicyKeepAll{
+				PolicyKeepAll: true,
+			}
+		}
+	}
+}

internal/config/migrations/001prunepolicy_test.go

@@ -0,0 +1,111 @@
+package migrations
+
+import (
+	"testing"
+
+	v1 "github.com/garethgeorge/backrest/gen/go/v1"
+	"google.golang.org/protobuf/encoding/protojson"
+	"google.golang.org/protobuf/proto"
+)
+
+func Test001Migration(t *testing.T) {
+	cases := []struct {
+		name   string
+		config string
+		want   *v1.Config
+	}{
+		{
+			name: "time bucketed policy",
+			config: `{
+				"plans": [
+					{
+						"retention": {
+							"keepHourly": 1,
+							"keepDaily": 2,
+							"keepWeekly": 3,
+							"keepMonthly": 4,
+							"keepYearly": 5
+						}
+					}
+				]
+			}`,
+			want: &v1.Config{
+				Plans: []*v1.Plan{
+					{
+						Retention: &v1.RetentionPolicy{
+							Policy: &v1.RetentionPolicy_PolicyTimeBucketed{
+								PolicyTimeBucketed: &v1.RetentionPolicy_TimeBucketedCounts{
+									Hourly:  1,
+									Daily:   2,
+									Weekly:  3,
+									Monthly: 4,
+									Yearly:  5,
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "keep all policy",
+			config: `{
+				"plans": [
+					{
+						"retention": {}
+					}
+				]
+			}`,
+			want: &v1.Config{
+				Plans: []*v1.Plan{
+					{
+						Retention: &v1.RetentionPolicy{
+							Policy: &v1.RetentionPolicy_PolicyKeepAll{
+								PolicyKeepAll: true,
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name: "keep by count",
+			config: `{
+				"plans": [
+					{
+						"retention": {
+							"keepLastN": 5
+						}
+					}
+				]
+			}`,
+			want: &v1.Config{
+				Plans: []*v1.Plan{
+					{
+						Retention: &v1.RetentionPolicy{
+							Policy: &v1.RetentionPolicy_PolicyKeepLastN{
+								PolicyKeepLastN: 5,
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		t.Run(tc.name, func(t *testing.T) {
+			config := v1.Config{}
+			err := protojson.Unmarshal([]byte(tc.config), &config)
+			if err != nil {
+				t.Fatalf("failed to unmarshal config: %v", err)
+			}
+
+			migration001PrunePolicy(&config)
+
+			if !proto.Equal(&config, tc.want) {
+				t.Errorf("got: %+v, want: %+v", &config, tc.want)
+			}
+		})
+	}
+}

internal/config/migrations/migrations.go

@@ -0,0 +1,10 @@
+package migrations
+
+import v1 "github.com/garethgeorge/backrest/gen/go/v1"
+
+func ApplyMigrations(config *v1.Config) {
+	if config.Version <= 1 {
+		migration001PrunePolicy(config)
+	}
+	config.Version = 1
+}

proto/v1/config.proto

@@ -8,6 +8,7 @@ option go_package = "github.com/garethgeorge/backrest/gen/go/v1";
 message Config {
   // modification number, used for read-modify-write consistency in the UI. Incremented on every write.
   int32 modno = 1 [json_name="modno"];
+  int32 version = 6 [json_name="version"]; // version of the config file format. Used to determine when to run migrations.
 
   // override the hostname tagged on backups. If provided it will be used in addition to tags to group backups.
   string host = 2 [json_name="host"];
@@ -40,16 +41,29 @@ message Plan {
 }
 
 message RetentionPolicy {
-  // max_unused_limit is used to decide when forget should be run.
-  string max_unused_limit = 1 [json_name="maxUnusedLimit"]; // e.g. a percentage i.e. 25% or a number of megabytes.
-
-  int32 keep_last_n = 2 [json_name="keepLastN"]; // keep the last n snapshots.
-  int32 keep_hourly = 3 [json_name="keepHourly"]; // keep the last n hourly snapshots.
-  int32 keep_daily = 4 [json_name="keepDaily"]; // keep the last n daily snapshots.
-  int32 keep_weekly = 5 [json_name="keepWeekly"]; // keep the last n weekly snapshots.
-  int32 keep_monthly = 6 [json_name="keepMonthly"]; // keep the last n monthly snapshots.
-  int32 keep_yearly = 7 [json_name="keepYearly"]; // keep the last n yearly snapshots.
-  string keep_within_duration = 8 [json_name="keepWithinDuration"]; // keep snapshots within a duration e.g. 1y2m3d4h5m6s
+  string max_unused_limit = 1 [json_name="maxUnusedLimit", deprecated = true]; 
+
+  int32 keep_last_n = 2 [json_name="keepLastN", deprecated = true];
+  int32 keep_hourly = 3 [json_name="keepHourly", deprecated = true];
+  int32 keep_daily = 4 [json_name="keepDaily", deprecated = true];
+  int32 keep_weekly = 5 [json_name="keepWeekly", deprecated = true];
+  int32 keep_monthly = 6 [json_name="keepMonthly", deprecated = true];
+  int32 keep_yearly = 7 [json_name="keepYearly", deprecated = true];
+  string keep_within_duration = 8 [json_name="keepWithinDuration", deprecated = true]; // keep snapshots within a duration e.g. 1y2m3d4h5m6s
+
+  oneof policy {
+    int32 policy_keep_last_n = 10 [json_name="policyKeepLastN"];
+    TimeBucketedCounts policy_time_bucketed = 11 [json_name="policyTimeBucketed"];
+    bool policy_keep_all = 12 [json_name="policyKeepAll"];
+  }
+
+  message TimeBucketedCounts {
+    int32 hourly = 1 [json_name="hourly"]; // keep the last n hourly snapshots.
+    int32 daily = 2 [json_name="daily"]; // keep the last n daily snapshots.
+    int32 weekly = 3 [json_name="weekly"]; // keep the last n weekly snapshots.
+    int32 monthly = 4 [json_name="monthly"]; // keep the last n monthly snapshots.
+    int32 yearly = 5 [json_name="yearly"];  // keep the last n yearly snapshots.
+  }
 }
 
 message PrunePolicy {