Add a isSwapOnAccordingToProcSwaps() function and swap utils unit tests

Signed-off-by: Itamar Holder <iholder@redhat.com>

pkg/kubelet/util/swap/swap_util.go

@@ -17,8 +17,10 @@ limitations under the License.
 package swap
 
 import (
+	"bytes"
 	"os"
 	sysruntime "runtime"
+	"strings"
 	"sync"
 
 	"k8s.io/apimachinery/pkg/util/version"
@@ -83,3 +85,14 @@ func IsTmpfsNoswapOptionSupported(mounter mount.Interface) bool {
 
 	return tmpfsNoswapOptionSupported
 }
+
+// gets /proc/swaps's content as an input, returns true if swap is enabled.
+func isSwapOnAccordingToProcSwaps(procSwapsContent []byte) bool {
+	procSwapsContent = bytes.TrimSpace(procSwapsContent) // extra trailing \n
+	procSwapsStr := string(procSwapsContent)
+	procSwapsLines := strings.Split(procSwapsStr, "\n")
+
+	// If there is more than one line (table headers) in /proc/swaps then swap is enabled
+	klog.InfoS("Swap is on", "/proc/swaps contents", procSwapsStr)
+	return len(procSwapsLines) > 1
+}

pkg/kubelet/util/swap/swap_util_test.go

@@ -0,0 +1,66 @@
+/*
+Copyright 2024 The Kubernetes Authors.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package swap
+
+import "testing"
+
+func TestIsSwapEnabled(t *testing.T) {
+	testCases := []struct {
+		name             string
+		procSwapsContent string
+		expectedEnabled  bool
+	}{
+		{
+			name:             "empty",
+			procSwapsContent: "",
+			expectedEnabled:  false,
+		},
+		{
+			name: "with swap enabled, one partition",
+			procSwapsContent: `
+Filename				Type		Size		Used		Priority
+/dev/dm-1               partition	33554428	0		-2
+`,
+			expectedEnabled: true,
+		},
+		{
+			name: "with swap enabled, 2 partitions",
+			procSwapsContent: `
+Filename				Type		Size		Used		Priority
+/dev/dm-1               partition	33554428	0		-2
+/dev/zram0              partition	8388604		0		100
+`,
+			expectedEnabled: true,
+		},
+		{
+			name: "empty lines",
+			procSwapsContent: `
+
+`,
+			expectedEnabled: false,
+		},
+	}
+
+	for _, tc := range testCases {
+		t.Run(tc.name, func(t *testing.T) {
+			isEnabled := isSwapOnAccordingToProcSwaps([]byte(tc.procSwapsContent))
+			if isEnabled != tc.expectedEnabled {
+				t.Errorf("expected %v, got %v", tc.expectedEnabled, isEnabled)
+			}
+		})
+	}
+}