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Merge pull request #59404 from ohmystack/docker-mem-swap

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Automatic merge from submit-queue (batch tested with PRs 50724, 59025, 59710, 59404, 59958). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

dockertools: disable MemorySwap on Linux

In this commit, set `MemorySwap` the same with `Memory` to prevent using swap on Linux.

**What this PR does / why we need it**:

In #39731, @pires tried to disable swap on Linux by setting `MemorySwap` to 0.
However, according to [Docker's docs](https://docs.docker.com/config/containers/resource_constraints/#--memory-swap-details), setting `MemorySwap` to 0 is treated as unset, and its [default behavior](https://github.com/moby/moby/blob/v17.05.0-ce/daemon/daemon_unix.go#L266-L269) is to set to twice the size of `Memory`, which can still cause the container to use the swap.

**Which issue(s) this PR fixes** :

This issue was mentioned in this comment: https://github.com/kubernetes/kubernetes/issues/7294#issuecomment-362722637

**Special notes for your reviewer**:

1. For the case on Windows, we can still use the 0 because [Windows does not support `MemorySwap`](https://github.com/moby/moby/blob/v17.05.0-ce/daemon/daemon_windows.go#L185-L187).
2. There is another place using the `DefaultMemorySwap()` is for [sandbox](https://github.com/kubernetes/kubernetes/blob/v1.9.2/pkg/kubelet/dockershim/docker_sandbox.go#L505).
Maybe setting the sandbox's `MemorySwap` to 0 is fine. I didn't change that.

**Release note**:

```release-note
dockertools: disable memory swap on Linux.
```
This commit is contained in:
Kubernetes Submit Queue 2018-02-26 21:34:42 -08:00 committed by GitHub
commit 89e433fca1
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3
pkg/kubelet/dockershim/helpers_linux.go
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@ -104,8 +104,9 @@ func (ds *dockerService) updateCreateConfig(
rOpts := lc.GetResources()
if rOpts != nil {
createConfig.HostConfig.Resources = dockercontainer.Resources{
// Memory and MemorySwap are set to the same value, this prevents containers from using any swap.
Memory: rOpts.MemoryLimitInBytes,
MemorySwap: DefaultMemorySwap(),
MemorySwap: rOpts.MemoryLimitInBytes,
CPUShares: rOpts.CpuShares,
CPUQuota: rOpts.CpuQuota,
CPUPeriod: rOpts.CpuPeriod,