ulimit-adjuster

README

ulimit Adjuster Plugin

This sample plugin can adjust ulimits for containers using pod annotations.

Annotations

ulimits are annotated using the key ulimits.nri.containerd.io/container.$CONTAINER_NAME, which adjusts ulimits for $CONTAINER_NAME. The ulimit names are the valid names of Linux resource limits, which can be seen on the setrlimit(2) manual page.

The annotation syntax for ulimit adjustment is

- type: RLIMIT_NOFILE
  soft: 1024
  hard: 4096
- path: RLIMIT_MEMLOCK
  soft: 1073741824
  hard: 1073741824
  ...

All fields are mandatory (soft and hard will be interpreted as 0 if missing). The type field accepts names in uppercase letters ("RLIMIT_NOFILE"), lowercase letters ("rlimit_memlock"), and omitting the "RLIMIT_" prefix ("nproc").

Testing

You can test this plugin using a kubernetes cluster/node with a container runtime that has NRI support enabled. Start the plugin on the target node (ulimit-adjuster -idx 10), create a pod with some annotated ulimits, then verify that those get adjusted in the container. See the sample pod spec for an example.