https://github.com/16Bitt/kubemem

A small binary to probe memory usage in a kubernetes pod
https://github.com/16Bitt/kubemem

docker kubernetes

Last synced: 2 months ago
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A small binary to probe memory usage in a kubernetes pod

• Host: GitHub
• URL: https://github.com/16Bitt/kubemem
• Owner: 16Bitt
• Created: 2019-09-23T01:53:38.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2023-09-28T11:53:06.000Z (9 months ago)
• Last Synced: 2024-01-20T21:51:15.485Z (5 months ago)
• Topics: docker, kubernetes
• Language: C
• Size: 9.77 KB
• Stars: 42
• Watchers: 6
• Forks: 8
• Open Issues: 3
• Metadata Files:
  • Readme: README.md

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• awesome-cloud-native - Kubemem - A small binary to probe memory usage in a kubernetes pod. (Observability)

README

        
# Kubemem

Kubemem is a small binary intended to be used as a liveness probe inside of your

Kubernetes applications that will allow graceful failure when the memory starts

to get too high. As it is not a shell script, it should be fast and portable for

your containers.

> Kubernetes already stops containers from using too much memory! What's the point?

Kubernetes [does not offer a way](https://github.com/kubernetes/kubernetes/issues/40157)

to add a graceful handler for OOM killed containers currently, so this is a nice medium.

Where I work, we have long running Sidekiq jobs with pods that should try to exit

gracefully but are instead immediately trashed once they hit the memory threshold.

## How it works

Kubemem has three options:

* a warning percentage: When your RAM usage hits this threshold, kubemem will log the warning

* a failure percentage: When your RAM usage hits this threshold, kubemem will exit with

  a non-zero exit code, causing kubernetes to trigger a graceful kill of your pod.

* a logfile path

Kubemem will use the cgroup filesystem to get memory info, and then use your options

to either log or fail.

## Usage

First, pick the tag you'd like to use:

* glibc: Debian-based builds

* musl: This is what you'll select for alpine

Simply add this container as another stage in your build:

```Dockerfile

FROM sixteenbitt/kubemem:glibc AS kubemem

# Do your normal build

COPY --from=kubemem /bin/kubemem /bin/kubemem

```

And then add a probe to your deployment:

```yaml

    livenessProbe:

      exec:

        command:

        - kubemem

        - --failure

        - "95" # Fail at 95% memory

        - --warning

        - "85" # Warn at 85% or greater memory usage

        - --logfile

        - /proc/1/fd/1 # Write to PID 1's output, allowing logging

      initialDelaySeconds: 5

      periodSeconds: 5

```

If you'd like to play around with it, you can run it from the command line:

```sh

docker run sixteenbitt/kubemem:musl kubemem --warning 80 --failure 90

```

## A note about logging

Kubernetes currently aggregates probe logs in kubelet, and only if logging is set to

verbosity level 4 or higher. See [this issue](https://github.com/16Bitt/kubemem/issues/1)

for more info about how kubernetes handles probe logs if you'd like to capture them.

As a workaround, set your logfile parameter to `/proc/1/fd/1` to write to the containers

PID 1 stdout for logging.