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Merge pull request #124060 from iholder101/swap/tmpfs-noswap
[KEP-2400] Mount tmpfs memory-backed volumes with a noswap option if supported
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,136 @@ | ||
| /* | ||
| 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 ( | ||
| "bytes" | ||
| "errors" | ||
| "os" | ||
| sysruntime "runtime" | ||
| "strings" | ||
| "sync" | ||
|
|
||
| "k8s.io/apimachinery/pkg/util/version" | ||
| "k8s.io/klog/v2" | ||
| utilkernel "k8s.io/kubernetes/pkg/util/kernel" | ||
| "k8s.io/mount-utils" | ||
| ) | ||
|
|
||
| var ( | ||
| tmpfsNoswapOptionSupported bool | ||
| tmpfsNoswapOptionAvailabilityOnce sync.Once | ||
| swapOn bool | ||
| swapOnErr error | ||
| swapOnOnce sync.Once | ||
| ) | ||
|
|
||
| const TmpfsNoswapOption = "noswap" | ||
|
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| func IsTmpfsNoswapOptionSupported(mounter mount.Interface, mountPath string) bool { | ||
| isTmpfsNoswapOptionSupportedHelper := func() bool { | ||
| if sysruntime.GOOS == "windows" { | ||
| return false | ||
| } | ||
|
|
||
| kernelVersion, err := utilkernel.GetVersion() | ||
| if err != nil { | ||
| klog.ErrorS(err, "cannot determine kernel version, unable to determine is tmpfs noswap is supported") | ||
| return false | ||
| } | ||
|
|
||
| if kernelVersion.AtLeast(version.MustParseGeneric(utilkernel.TmpfsNoswapSupportKernelVersion)) { | ||
| return true | ||
| } | ||
|
|
||
| if mountPath == "" { | ||
| klog.ErrorS(errors.New("mount path is empty, falling back to /tmp"), "") | ||
| } | ||
|
|
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| mountPath, err = os.MkdirTemp(mountPath, "tmpfs-noswap-test-") | ||
| if err != nil { | ||
| klog.InfoS("error creating dir to test if tmpfs noswap is enabled. Assuming not supported", "mount path", mountPath, "error", err) | ||
| return false | ||
| } | ||
|
|
||
| defer func() { | ||
| err = os.RemoveAll(mountPath) | ||
| if err != nil { | ||
| klog.ErrorS(err, "error removing test tmpfs dir", "mount path", mountPath) | ||
| } | ||
| }() | ||
|
|
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| err = mounter.MountSensitiveWithoutSystemd("tmpfs", mountPath, "tmpfs", []string{TmpfsNoswapOption}, nil) | ||
| if err != nil { | ||
| klog.InfoS("error mounting tmpfs with the noswap option. Assuming not supported", "error", err) | ||
| return false | ||
| } | ||
|
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| err = mounter.Unmount(mountPath) | ||
| if err != nil { | ||
| klog.ErrorS(err, "error unmounting test tmpfs dir", "mount path", mountPath) | ||
| } | ||
|
|
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| return true | ||
| } | ||
|
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| tmpfsNoswapOptionAvailabilityOnce.Do(func() { | ||
| tmpfsNoswapOptionSupported = isTmpfsNoswapOptionSupportedHelper() | ||
| }) | ||
|
|
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| return tmpfsNoswapOptionSupported | ||
| } | ||
|
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| // 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") | ||
|
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| // 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 | ||
| } | ||
|
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| // IsSwapOn detects whether swap in enabled on the system by inspecting | ||
| // /proc/swaps. If the file does not exist, an os.NotFound error will be returned. | ||
| // If running on windows, swap is assumed to always be false. | ||
| func IsSwapOn() (bool, error) { | ||
| isSwapOnHelper := func() (bool, error) { | ||
| if sysruntime.GOOS == "windows" { | ||
| return false, nil | ||
| } | ||
|
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| const swapFilePath = "/proc/swaps" | ||
| procSwapsContent, err := os.ReadFile(swapFilePath) | ||
| if err != nil { | ||
| if os.IsNotExist(err) { | ||
| klog.InfoS("File does not exist, assuming that swap is disabled", "path", swapFilePath) | ||
| return false, nil | ||
| } | ||
|
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| return false, err | ||
| } | ||
|
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| return isSwapOnAccordingToProcSwaps(procSwapsContent), nil | ||
| } | ||
|
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| swapOnOnce.Do(func() { | ||
| swapOn, swapOnErr = isSwapOnHelper() | ||
| }) | ||
|
|
||
| return swapOn, swapOnErr | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -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 | ||
|
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| import "testing" | ||
|
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| 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, | ||
| }, | ||
| } | ||
|
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| 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) | ||
| } | ||
| }) | ||
| } | ||
| } |
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