emptyDir with medium: Memory ignores sizeLimit · Issue #63126 · kubernetes/kubernetes · GitHub

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emptyDir with medium: Memory ignores sizeLimit · Issue #63126 · kubernetes/kubernetes · GitHub

#emptyDir with medium: Memory ignores sizeLimit · Issue #63126 · kubernetes/kubernetes · GitHub| 来源: 网络整理| 查看: 265

Is this a BUG REPORT or FEATURE REQUEST?:

/kind bug

What happened:

The tmpfs volume that's created with emptyDir doesn't have the correct size limit. In fact, the tmpfs volume size is always half of the available RAM on the Kubernetes node, which is the default behavior on a Linux kernel (https://www.kernel.org/doc/Documentation/filesystems/tmpfs.txt). This implies that the size option was likely not provided when mounting a tmpfs. This is similar to the issue here: #48912.

Note: All the Kubernetes components have the necessary feature gates enabled.

What you expected to happen:

The tmpfs volume should respect the sizeLimit parameter, unless the sizeLimit parameter is not meant for tmpfs.

How to reproduce it (as minimally and precisely as possible):

Step 1: Create a deployment that with an emptyDir volume with medium set to Memory and sizeLimit set to 1Gi.

$ cat sample.yaml apiVersion: apps/v1 kind: Deployment metadata: name: test spec: selector: matchLabels: app: test template: metadata: labels: app: test spec: containers: - image: nginx name: nginx volumeMounts: - mountPath: /scratch name: scratch volumes: - name: scratch emptyDir: medium: Memory sizeLimit: "1Gi" $ kubectl apply -f sample.yaml deployment "test" configured

Step 2: Inspect the volume mount and the size is not 1GB. Instead, the size is 126GB, because the Kubernetes node has 256GB of available RAM.

kubectl exec -it test-56f7bb87d5-j68n5 bash root@test-56f7bb87d5-j68n5:/# mount -l | grep scratch tmpfs on /scratch type tmpfs (rw,relatime) root@test-56f7bb87d5-j68n5:/# df -h /scratch Filesystem Size Used Avail Use% Mounted on tmpfs 126G 0 126G 0% /scratch

Step 3: When exporting the deployment manifest file, the sizeLimit option is retained, demonstrating that the necessary feature gates were enabled.

kubectl get pods test-56f7bb87d5-j68n5 -o yaml --export apiVersion: v1 kind: Pod metadata: creationTimestamp: null generateName: test-56f7bb87d5- labels: app: test pod-template-hash: "1293664381" ownerReferences: - apiVersion: extensions/v1beta1 blockOwnerDeletion: true controller: true kind: ReplicaSet name: test-56f7bb87d5 uid: 63b2a2d3-4815-11e8-aacf-ec0d9a749964 selfLink: /api/v1/namespaces/default/pods/test-56f7bb87d5-j68n5 spec: containers: - image: nginx imagePullPolicy: Always name: nginx resources: {} terminationMessagePath: /dev/termination-log terminationMessagePolicy: File volumeMounts: - mountPath: /scratch name: scratch - mountPath: /var/run/secrets/kubernetes.io/serviceaccount name: default-token-qb9lt readOnly: true dnsPolicy: ClusterFirst nodeName: restartPolicy: Always schedulerName: default-scheduler securityContext: {} serviceAccount: default serviceAccountName: default terminationGracePeriodSeconds: 30 tolerations: - effect: NoExecute key: node.kubernetes.io/not-ready operator: Exists tolerationSeconds: 300 - effect: NoExecute key: node.kubernetes.io/unreachable operator: Exists tolerationSeconds: 300 volumes: - emptyDir: medium: Memory sizeLimit: 1Gi name: scratch - name: default-token-qb9lt secret: defaultMode: 420 secretName: default-token-qb9lt status: phase: Pending qosClass: BestEffort

Anything else we need to know?:

Environment:

Kubernetes version (use kubectl version): $ kubectl version Client Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:21:50Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"} Server Version: version.Info{Major:"1", Minor:"9", GitVersion:"v1.9.6", GitCommit:"9f8ebd171479bec0ada837d7ee641dec2f8c6dd1", GitTreeState:"clean", BuildDate:"2018-03-21T15:13:31Z", GoVersion:"go1.9.3", Compiler:"gc", Platform:"linux/amd64"} Cloud provider or hardware configuration:

The api server, controller manager, scheduler, and kubelets have the following feature gates enabled: --feature-gates=PersistentLocalVolumes=true,VolumeScheduling=true,MountPropagation=true,LocalStorageCapacityIsolation=true,DevicePlugins=true

The only feature gate that is needed is LocalStorageCapacityIsolation, but the other features are enabled for other reasons.

The Kubernetes nodes in this cluster have 256GB of RAM.

$ free -g total used free shared buff/cache available Mem: 251 2 238 2 10 245 OS (e.g. from /etc/os-release): cat /etc/os-release NAME="Ubuntu" VERSION="16.04.4 LTS (Xenial Xerus)" ID=ubuntu ID_LIKE=debian PRETTY_NAME="Ubuntu 16.04.4 LTS" VERSION_ID="16.04" HOME_URL="http://www.ubuntu.com/" SUPPORT_URL="http://help.ubuntu.com/" BUG_REPORT_URL="http://bugs.launchpad.net/ubuntu/" VERSION_CODENAME=xenial UBUNTU_CODENAME=xenial Kernel (e.g. uname -a): uname -a Linux 4.4.0-116-generic #140-Ubuntu SMP Mon Feb 12 21:23:04 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux Install tools:

kubeadm.

Others:

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