Add fuzz testing with CI and fix snapshot ID panic

.github/workflows/fuzz.yml

@@ -0,0 +1,40 @@
+name: Fuzz
+
+on:
+  pull_request:
+    paths-ignore:
+      - 'docs/**'
+      - 'charts/**'
+  schedule:
+    # Nightly at 04:00 UTC (06:00 CEST) with longer fuzz duration
+    - cron: '0 4 * * *'
+
+jobs:
+  fuzz:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        fuzz-target:
+          - { package: ./restic/kubernetes/, func: FuzzFilterAndConvert }
+          - { package: ./restic/logging/, func: FuzzBackupOutputParser }
+          - { package: ./operator/utils/, func: FuzzJsonArgsArrayUnmarshalJSON }
+    steps:
+      - uses: actions/checkout@v6
+
+      - name: Determine Go version from go.mod
+        run: echo "GO_VERSION=$(go mod edit -json | jq -r .Go)" >> $GITHUB_ENV
+
+      - uses: actions/setup-go@v6
+        with:
+          go-version: ${{ env.GO_VERSION }}
+
+      - name: Set fuzz duration
+        run: |
+          if [ "${{ github.event_name }}" = "schedule" ]; then
+            echo "FUZZ_TIME=5m" >> $GITHUB_ENV
+          else
+            echo "FUZZ_TIME=60s" >> $GITHUB_ENV
+          fi
+
+      - name: Run fuzz test
+        run: go test ${{ matrix.fuzz-target.package }} -fuzz=${{ matrix.fuzz-target.func }} -fuzztime=$FUZZ_TIME

operator/utils/utils_fuzz_test.go

@@ -0,0 +1,25 @@
+package utils
+
+import (
+	"testing"
+)
+
+func FuzzJsonArgsArrayUnmarshalJSON(f *testing.F) {
+	// Seed with realistic inputs
+	f.Add([]byte(`"--verbose"`))
+	f.Add([]byte(`["--verbose", "--dry-run"]`))
+	f.Add([]byte(`[]`))
+	f.Add([]byte(`""`))
+	f.Add([]byte(`null`))
+	f.Add([]byte(`123`))
+	f.Add([]byte(`{"key": "value"}`))
+	f.Add([]byte(`[1, 2, 3]`))
+	f.Add([]byte(`[null]`))
+	f.Add([]byte(``))
+
+	f.Fuzz(func(t *testing.T, data []byte) {
+		var arr JsonArgsArray
+		// Must not panic — errors are acceptable
+		_ = arr.UnmarshalJSON(data)
+	})
+}

restic/kubernetes/snapshots.go

@@ -98,9 +98,14 @@ func filterAndConvert(list []dto.Snapshot, namespace, repository string) *k8upv1
 			continue
 		}
 
+		name := snapshot.ID
+		if len(name) > 8 {
+			name = name[:8]
+		}
+
 		finalList.Items = append(finalList.Items, k8upv1.Snapshot{
 			ObjectMeta: metav1.ObjectMeta{
-				Name:      snapshot.ID[:8],
+				Name:      name,
 				Namespace: namespace,
 			},
 			Spec: k8upv1.SnapshotSpec{

restic/kubernetes/snapshots_fuzz_test.go

@@ -0,0 +1,38 @@
+package kubernetes
+
+import (
+	"testing"
+	"time"
+
+	"github.com/k8up-io/k8up/v2/restic/dto"
+)
+
+func FuzzFilterAndConvert(f *testing.F) {
+	// Seed with realistic inputs
+	f.Add("abc12345678", "default", "s3:http://minio:9000/backup")
+	f.Add("short", "default", "s3:http://minio:9000/backup")
+	f.Add("", "default", "s3:http://minio:9000/backup")
+	f.Add("abcdefgh", "test-ns", "rest:https://user:pass@host/path")
+	f.Add("1234567", "default", "") // 7 chars - just under the [:8] slice
+
+	f.Fuzz(func(t *testing.T, id, namespace, repository string) {
+		snapshots := []dto.Snapshot{
+			{
+				ID:       id,
+				Time:     time.Now(),
+				Hostname: namespace, // must match namespace to pass filter
+				Paths:    []string{"/data"},
+			},
+		}
+
+		// This must not panic
+		result := filterAndConvert(snapshots, namespace, repository)
+
+		// If snapshot passed the filter, verify basic properties
+		if len(result.Items) > 0 {
+			if result.Items[0].Namespace != namespace {
+				t.Errorf("expected namespace %q, got %q", namespace, result.Items[0].Namespace)
+			}
+		}
+	})
+}

restic/logging/logging_fuzz_test.go

@@ -0,0 +1,38 @@
+package logging
+
+import (
+	"testing"
+
+	"github.com/go-logr/logr"
+)
+
+func FuzzBackupOutputParser(f *testing.F) {
+	// Seed with realistic restic JSON output
+	f.Add(`{"message_type":"status","percent_done":0.5,"total_files":100,"files_done":50}`)
+	f.Add(`{"message_type":"summary","files_new":10,"files_changed":2,"total_duration":1.5,"snapshot_id":"abc12345"}`)
+	f.Add(`{"message_type":"error","error":{"Op":"read","Path":"/data/file","Err":13},"during":"scan","item":"/data/file"}`)
+	f.Add(`not json at all`)
+	f.Add(`{}`)
+	f.Add(`{"message_type":"unknown"}`)
+	f.Add(``)
+	f.Add(`{"message_type":"status","percent_done":-1}`)
+	f.Add(`{"message_type":"summary","total_duration":999999999999}`)
+
+	f.Fuzz(func(t *testing.T, input string) {
+		summaryCalled := false
+		summaryFunc := func(summary BackupSummary, errorCount int, folder string, startTimestamp, endTimestamp int64) {
+			summaryCalled = true
+			_ = summaryCalled
+		}
+
+		parser := &BackupOutputParser{
+			log:            logr.Discard(),
+			folder:         "/data",
+			summaryFunc:    summaryFunc,
+			percentageFunc: IgnorePercentage,
+		}
+
+		// Must not panic
+		parser.out(input)
+	})
+}