CODEWITHSUNDEEP
kuberneteskubernetes-helmdaemonset
Somnath Pathak
Somnath Pathak

Reputation: 171

How to create a daemonset to manage (create or remove or check if exists then do nothing) a list of directories under "/var/log" parent directory

The directories to be created/managed should be dynamic and be read from values.yaml file of the helm release.

The Daemonset definition which I could think of is mentioned below:

apiVersion: apps/v1
kind: DaemonSet
metadata:
  name: create-directory
spec:
  selector:
    matchLabels:
      app: create-directory
  template:
    metadata:
      labels:
        app: create-directory
    spec:
      # use default service-account with scc role-binding
      ServiceAccountName: default
      containers:
      - name: create-directory
        image: "{{ .Values.container.image }}"
        imagePullPolicy: IfNotPresent
        command: ["/bin/sh", "-c"]
        args:
          - |
            {{- range .Values.directories }}

            dir_path="/var/log/at/{{ . }}"
            echo $dir_path

            # Check if the directory exists
            if [ -d "$dir_path" ]; then
              echo "Directory $dir_path already exists."
            else
              # Create the directory
              mkdir -p "$dir_path" && echo "Directory $dir_path created."
            fi

            {{- end }}
            
            while true; do
              sleep 100000;
            done
        # run the container as root
        securityContext:
          runAsUser: 0
        volumeMounts:
          - name: at-volume
            mountPath: /var/log/at
      volumes:
        - name: at-volume
          hostPath:
            path: /var/log/at

where the values.yaml file for the helm chart looks like below:

container:
  image: registry.access.redhat.com/ubi8/toolbox:8.5
directories:
  - directory1
  - directory2

I need the guidance on the below mentioned:

  1. Is my approach of using the sleep to keep the pod alive and stop it from being rescheduling once the directory check script is executed, is correct or does the community recommend something else?
  2. How can I remove directories once they are removed from the values.yaml directories list?

UPDATE For (1) I could find a solution: "Run-once Kubernetes DaemonSet pods"

Upvotes: 0

Views: 150

Answers (1)

Marco Caberletti
Marco Caberletti

Reputation: 1896

For the question #2, you can try something:

rm -rf !({{ .Values.directories | join "|" }})

This will remove all the directories except the ones listed. See here for more examples.

Upvotes: 0

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