DaemonSet use cases

Learn DaemonSet use cases.

DaemonSet use cases

A DaemonSet's typical jobs are infrastructure tasks requiring an agent on every node:

Log collection: Fluent Bit, Fluentd, Promtail send the container logs on the node to a central place.
Monitoring: node-exporter and the Datadog agent collect node metrics.
Networking: kube-proxy, Calico, Cilium manage the node's network rules.
Storage: CSI node plugins attach disks to the node.
Security: tools like Falco watch kernel events.

kubectl get ds -n kube-system
NAME         DESIRED   CURRENT   READY
kube-proxy   3         3         3
calico-node  3         3         3

Resource limits matter

Since a DaemonSet pod runs on every node, its resource consumption is multiplied by the node count; an agent using 200 MiB of memory on 100 nodes means 20 GiB in total. Also, a priority class is given so critical agents aren't evicted:

      priorityClassName: system-node-critical
      containers:
        - name: fluent-bit
          image: fluent/fluent-bit:3.1
          resources:
            requests: {cpu: 50m, memory: 64Mi}
            limits:   {memory: 128Mi}

Exercise A log collector

Write a DaemonSet template's spec section (starting with spec:): priorityClassName: system-node-critical; container named fluent-bit, image fluent/fluent-bit:3.1; resources.requests cpu: 50m, memory: 64Mi; resources.limits memory: 128Mi.

Show example solution

spec:
  priorityClassName: system-node-critical
  containers:
    - name: fluent-bit
      image: fluent/fluent-bit:3.1
      resources:
        requests:
          cpu: 50m
          memory: 64Mi
        limits:
          memory: 128Mi

Test yourself

Which is not suitable for a DaemonSet?
- A web API serving user requests
- A log collector
- A node metrics agent
- A network plugin
Show answer

A web API serving user requests — A web API's replica count depends on load, not the node count.

Give the critical agent priority.

      ____: system-node-critical

Show answer

      priorityClassName: system-node-critical

Match the tools.

Fluent Bit

Log collection
node-exporter

Metrics
Calico

Networking
Falco

Security

Next lesson: Updating a DaemonSet

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