When the kubelet reports that the node is in diskpressure?

Question

I know that the kubelet reports that the node is in diskpressure if there is not enough space on the node.
But I want to know the exact threshold of diskpressure.
Please let me know the source code of the kubelet related this issue if you could.
Or I really thanks for your help about the official documentation from k8s or sth else.
Thanks again!!

Answer 1

Kubelet running on the node will report the disk pressure depending on hard or soft eviction threshold values which is being set. if nothing being set it will be all default values. Please refer kubernetes documentation

Below are values which will be used

DiskPressure - nodefs.available, nodefs.inodesFree, imagefs.available, or imagefs.inodesFree

Answer 2

Disk pressure is a condition indicating that a node is using too much disk space or is using disk space too fast, according to the thresholds you have set in your Kubernetes configuration.

DaemonSet can deploy apps to multiple nodes in a single step. Like deployments, DaemonSets must be applied using kubectl before they can take effect.

Since kubernetes is running on Linux,this is easily done by running du command.you can either manually ssh into each kubernetes nodes,or use a Daemonset As follows:

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: disk-checker
  labels:
    app: disk-checker
spec:
  selector:
    matchLabels:
      app: disk-checker
  template:
    metadata:
      labels:
        app: disk-checker
    spec:
      hostPID: true
      hostIPC: true
      hostNetwork: true
      containers:
      - resources:
          requests:
            cpu: 0.15
        securityContext:
          privileged: true
        image: busybox
        imagePullPolicy: IfNotPresent
        name: disk-checked
        command: ["/bin/sh"]
        args: ["-c", "du -a /host | sort -n -r | head -n 20"]
        volumeMounts:
        - name: host
          mountPath: "/host"
      volumes:
        - name: host
          hostPath:
            path: "/"

Available disk space and inodes on either the node's root filesystem or image filesystem has satisfied an eviction threshold, check complete Node Conditions for more details.

Ways to set Kubelet options:

1)Command line options like --eviction-hard.

2)Config file.

3)More recent is dynamic configuration.

When you experience an issue with node disk pressure, your immediate thoughts should be when you run into the issue: an error in garbage collecting or log files. Of course the better answer here is to clean up unused files (free up some disk space).

So Monitor your clusters and get notified of any node disks approaching pressure, and get the issue resolved before it starts killing other pods inside the cluster.