Question
DaemonSets will bypass the scheduler and deploy to nodes that are designated as "unschedulable"; however you can use a DaemonSet to deploy to a subset of all the nodes (according to page 109 of Kubernetes in Action). In the real world, what are daemonsets used for in Kubernetes?
Answer
- Monitoring of pods/nodes (such as Prometheus Node Exporter, New Relic, collectd, or a Datadog agent)
- Centralized logging of pods/nodes (Splunk, Fluentd, or logstash)
- To enable storage to be accessible for the node
- Enabling recommended-security on nodes to authenticate with AWS. (This was taken from https://github.com/jtblin/kube2iam.)
References
https://www.bmc.com/blogs/kubernetes-daemonset/
https://cloud.google.com/kubernetes-engine/docs/concepts/daemonset
https://medium.com/kubernetes-tutorials/a-guide-to-kubernetes-daemonsets-6db7920ad140