VMAgent DaemonSetMode: volumes/volumeMounts not working properly

[lexfrei]

Describe the bug

Multiple issues with volume configuration in daemonSetMode:

1. extraVolumes/extraVolumeMounts fields are ignored - CRD accepts them (due to x-kubernetes-preserve-unknown-fields), but operator code reads cr.Spec.Volumes, not cr.Spec.ExtraVolumes

2. volumes field doesn't override default - operator always creates persistent-queue-data as emptyDir first, user volumes are appended but don't replace it

3. volumeMounts field is not applied to DaemonSet containers

Documentation states:

Volume for the persistent-queue could be mounted with volumes and must have either hostPath or emptyDir.

None of these work as documented.

To Reproduce

apiVersion: operator.victoriametrics.com/v1beta1
kind: VMAgent
metadata:
  name: vmagent
  namespace: monitoring
spec:
  daemonSetMode: true
  selectAllByDefault: true
  remoteWrite:
    - url: http://vmsingle.monitoring.svc:8428/api/v1/write
  extraArgs:
    remoteWrite.tmpDataPath: /vmagent-wal
  volumes:
    - name: vmagent-wal-host
      hostPath:
        path: /var/lib/vmagent-wal
        type: DirectoryOrCreate
  volumeMounts:
    - name: vmagent-wal-host
      mountPath: /vmagent-wal

Result:

• Volume vmagent-wal-host IS added to DaemonSet
• VolumeMount is NOT added to container
• persistent-queue-data remains emptyDir

# Volumes - vmagent-wal-host present, but persistent-queue-data still emptyDir
kubectl get ds -n monitoring vmagent-vmagent -o jsonpath='{.spec.template.spec.volumes}' | jq .

# VolumeMounts - only config-out, user volumeMounts missing
kubectl get ds -n monitoring vmagent-vmagent -o jsonpath='{.spec.template.spec.containers[0].volumeMounts}' | jq .

Root cause analysis

Issue 1: extraVolumes ignored

Code in vmagent.go line 549:

volumes = append(volumes, cr.Spec.Volumes...)

Uses Volumes, not ExtraVolumes.

Issue 2: volumes don't override default

Code in vmagent.go around line 545:

if !cr.Spec.StatefulMode {
    volumes = append(volumes, corev1.Volume{
        Name: vmAgentPersistentQueueMountName,
        VolumeSource: corev1.VolumeSource{EmptyDir: &corev1.EmptyDirVolumeSource{}},
    })
}
volumes = append(volumes, cr.Spec.Volumes...)

Default emptyDir created first, user volumes appended (no override).

Issue 3: volumeMounts not applied

Code in vmagent.go line 536:

agentVolumeMounts = append(agentVolumeMounts, cr.Spec.VolumeMounts...)

VolumeMounts are added to agentVolumeMounts, but somewhere between newPodSpec() and final DaemonSet creation they are lost.

Environment

• Operator version: v0.66.1
• Kubernetes: v1.34.2+k3s1

Related

• Issue allowed override vmagent volume #450 fixed volume override for StatefulMode, DaemonSetMode was not addressed

[f41gh7]

Related configuration example https://github.com/VictoriaMetrics/operator/blob/master/config/examples/vmagent_daemonset.yaml that covers this case