Kubernetes node-exporter container is not working it shows this error message - Docker

Loopero
January 2, 2022
330 views
3 votes
3 Answers

Error: failed to start container "node-exporter": Error response from daemon: path /sys is mounted on /sys but it is not a shared or slave mount

shows that message here is the repository I took it from trying to make a node exporter to Grafana dashboard through Kubernetes pods followed this video and this repo

ERROR screenshot

Answers

- Ali
- May 12, 2022 at 7:45 am
- 0 votes
0
Well for me (Docker-Desktop in MacOS) this command saved my day:
```
kubectl patch ds monitoring-prometheus-node-exporter --type "json" -p '[{"op": "remove", "path" : "/spec/template/spec/containers/0/volumeMounts/2/mountPropagation"}]'
```
credit: GitHub Issues
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This work for me (Docker-Dektop in MacOs m1)

# Mount the node's root file system (/) at /host/root in the container
hostRootFsMount:
  enabled: false
  # Defines how new mounts in existing mounts on the node or in the container
  # are propagated to the container or node, respectively. Possible values are
  # None, HostToContainer, and Bidirectional. If this field is omitted, then
  # None is used. More information on:
  # https://kubernetes.io/docs/concepts/storage/volumes/#mount-propagation
  mountPropagation: HostToContainer

- AniketKariya
- March 16, 2023 at 2:31 pm
- 0 votes
0
What is the issue

This is not an issue of node exporter or helm chart or Kubernetes or docker but a limitation of docker desktop. Only people using Kubernetes on the docker desktop should be the ones facing the issue.

Take a look at the values.yaml from prometheus-node-exporter
```
# Mount the node's root file system (/) at /host/root in the container
hostRootFsMount:
  enabled: true
  # Defines how new mounts in existing mounts on the node or in the container
  # are propagated to the container or node, respectively. Possible values are
  # None, HostToContainer, and Bidirectional. If this field is omitted, then
  # None is used. More information on:
  # https://kubernetes.io/docs/concepts/storage/volumes/#mount-propagation
  mountPropagation: HostToContainer
```
It is using mount propagation. Now, take a look at the docker documentation::

Bind propagation defaults to rprivate for both bind mounts and volumes. It is only configurable for bind mounts, and only on Linux host machines. Bind propagation is an advanced topic and many users never need to configure it.

furthermore, and the most important one:

Okay but tell me how to solve it

You can turn off the hostRootFsMount, of course, by using the kubectl patch as suggested by Ali’s answer, or you can use
```
helm install prom prometheus-community/kube-prometheus-stack -f node-exporter-workaround.yaml
OR
helm install prom prometheus-community/kube-prometheus-stack --set prometheus-node-exporter.hostRootFsMount.enabled=false
```
```
# node-exporter-workaround.yaml
prometheus-node-exporter:
  hostRootFsMount:
    enabled: false
```
I am using kube-prometheus-stack chart in my case, and it contains the dependency of node exporter with the name prometheus-node-exporter, thus the first line of the yaml contains prometheus-node-exporter, and it can be different if the name of the dependency is different for the chart you are using.
```
dependencies:
  ...
  - name: prometheus-node-exporter
    version: "4.14.*"
    repository: https://prometheus-community.github.io/helm-charts
    condition: nodeExporter.enabled
```
If you are using the prometheus-node-exporter chart directly, then you can install it with --set hostRootFsMount.enabled=false

BUT

Bear in mind that by disabling mount propagation node-exporter won’t be able to collect all data needed for grafana dashboards and for alerts. — paulfantom [maintainer]

So, what does this mean?
It means this is a workaround and not a solution. There are side effects to it. But on the bright side, this is a docker desktop issue. Prometheus should work fine on your production clusters. But if you are using docker desktop as your production env, then you need to reconsider some of your life choices. Have a nice day! 🙂
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