Disk Limit in a Docker-based K8s Cluster¶
Docker provides configuration options to limit the disk space that a container can use. This limit affects both the image and the container's filesystem, with a default value of 10G. This article will guide you on how to configure parameters to change this value when deploying a cluster.
Prerequisites¶
According to the Docker official documentation on overlay2-options, before configuring Docker overlay2.size, you need to adjust the filesystem type to xfs in the operating system.
- The cluster runtime is Docker.
- The node's operating system filesystem type is xfs.
Additionally, this procedure uses CentOS 7 as an example. The basic information of the node is as follows:
$ cat /etc/os-release
NAME="CentOS Linux"
VERSION="7 (Core)"
ID="centos"
ID_LIKE="rhel fedora"
VERSION_ID="7"
PRETTY_NAME="CentOS Linux 7 (Core)"
ANSI_COLOR="0;31"
CPE_NAME="cpe:/o:centos:centos:7"
HOME_URL="https://www.centos.org/"
BUG_REPORT_URL="https://bugs.centos.org/"
CENTOS_MANTISBT_PROJECT="CentOS-7"
CENTOS_MANTISBT_PROJECT_VERSION="7"
REDHAT_SUPPORT_PRODUCT="centos"
REDHAT_SUPPORT_PRODUCT_VERSION="7"
$ uname -a
Linux localhost.localdomain 3.10.0-957.el7.x86_64 # (1)!
- SMP Thu Nov 8 23:39:32 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
Operation Guide¶
-
Refer to the container management Create Cluster documentation. After filling in other information, navigate to the Advanced Configuration module.
-
In the Advanced Configuration interface, add the following line in the custom parameters:
This parameter limits the maximum disk usage of a single Docker container to 1G. Any write operations beyond 1G will be denied.
Validation¶
After the cluster deployment is complete, verify whether the container disk usage limit is effective.
-
Create a test container on the cluster node:
-
Enter the container and test the disk usage limit with a large file:
-
The expected behavior is that the creation of the initial 100M file
a
will succeed. However, when attempting to create another 100M fileb
, an error "No space left on device" will occur, indicating that the disk limit is in effect, as shown below: