Pods are run by the kubelet service that runs inside each node. There are three ways to instruct kubelet to run a Pod:
- By directly passing it the Pod configuration file (or a directory container configuration files) using kubelet --config <path-to-pod-config>. kubelet will poll this directory every 20 seconds for changes, and will start new containers or terminate containers based on any changes to the configuration file(s).
- By specifying an HTTP endpoint which returns with the Pod configuration files. Like the file option, kubelet polls the endpoint every 20 seconds.
- By using the Kubernetes API server to send any new pod manifests to kubelet.
The first two options are not ideal because:
- It relies on polling, ...
