api: limit maximum number of snapshots in history

This ensures that on repetitive failures, the number of snapshots does
not grow indefinitely due to there not being any in a superseded or
deployed state.

Signed-off-by: Hidde Beydals <hidde@hhh.computer>

api/v2beta2/helmrelease_types.go

@@ -37,6 +37,11 @@ const (
 	HelmReleaseFinalizer = "finalizers.fluxcd.io"
 )
 
+const (
+	// defaultMaxHistory is the default number of Helm release versions to keep.
+	defaultMaxHistory = 5
+)
+
 // Kustomize Helm PostRenderer specification.
 type Kustomize struct {
 	// Strategic merge and JSON patches, defined as inline YAML objects,
@@ -1200,7 +1205,7 @@ func (in HelmRelease) GetTimeout() metav1.Duration {
 // GetMaxHistory returns the configured MaxHistory, or the default of 5.
 func (in HelmRelease) GetMaxHistory() int {
 	if in.Spec.MaxHistory == nil {
-		return 5
+		return defaultMaxHistory
 	}
 	return *in.Spec.MaxHistory
 }

api/v2beta2/snapshot_types.go

@@ -81,11 +81,13 @@ func (in Snapshots) Previous(ignoreTests bool) *Snapshot {
 }
 
 // Truncate removes all Snapshots up to the Previous deployed Snapshot.
-// If there is no previous-deployed Snapshot, no Snapshots are removed.
+// If there is no previous-deployed Snapshot, the most recent 5 Snapshots are
+// retained.
 func (in *Snapshots) Truncate(ignoreTests bool) {
 	if in.Len() < 2 {
 		return
 	}
+
 	in.SortByVersion()
 	for i := range (*in)[1:] {
 		s := (*in)[i+1]
@@ -96,6 +98,13 @@ func (in *Snapshots) Truncate(ignoreTests bool) {
 			}
 		}
 	}
+
+	if in.Len() > defaultMaxHistory {
+		// If none of the Snapshots are deployed or superseded, and there
+		// are more than the defaultMaxHistory, truncate to the most recent
+		// Snapshots.
+		*in = (*in)[:defaultMaxHistory]
+	}
 }
 
 // Snapshot captures a point-in-time copy of the status information for a Helm release,

api/v2beta2/snapshot_types_test.go

@@ -258,6 +258,24 @@ func TestSnapshots_Truncate(t *testing.T) {
 				}},
 			},
 		},
+		{
+			name: "retains most recent snapshots when all have failed",
+			in: Snapshots{
+				{Version: 6, Status: "deployed"},
+				{Version: 5, Status: "failed"},
+				{Version: 4, Status: "failed"},
+				{Version: 3, Status: "failed"},
+				{Version: 2, Status: "failed"},
+				{Version: 1, Status: "failed"},
+			},
+			want: Snapshots{
+				{Version: 6, Status: "deployed"},
+				{Version: 5, Status: "failed"},
+				{Version: 4, Status: "failed"},
+				{Version: 3, Status: "failed"},
+				{Version: 2, Status: "failed"},
+			},
+		},
 		{
 			name: "without previous snapshot",
 			in: Snapshots{