If you are using a released version of Kubernetes, you should refer to the docs that go with that version.
The latest 1.0.x release of this document can be found [here](http://releases.k8s.io/release-1.0/docs/admin/kubelet.md).Documentation for other releases can be found at releases.k8s.io.
The kubelet is the primary "node agent" that runs on each node. The kubelet works in terms of a PodSpec. A PodSpec is a YAML or JSON object that describes a pod. The kubelet takes a set of PodSpecs that are provided through various mechanisms (primarily through the apiserver) and ensures that the containers described in those PodSpecs are running and healthy.
Other than from an PodSpec from the apiserver, there are three ways that a container manifest can be provided to the Kubelet.
File: Path passed as a flag on the command line. This file is rechecked every 20 seconds (configurable with a flag).
HTTP endpoint: HTTP endpoint passed as a parameter on the command line. This endpoint is checked every 20 seconds (also configurable with a flag).
HTTP server: The kubelet can also listen for HTTP and respond to a simple API (underspec'd currently) to submit a new manifest.
--address=<nil>: The IP address for the Kubelet to serve on (set to 0.0.0.0 for all interfaces)
--allow-privileged=false: If true, allow containers to request privileged mode. [default=false]
--api-servers=[]: List of Kubernetes API servers for publishing events, and reading pods and services. (ip:port), comma separated.
--cadvisor-port=0: The port of the localhost cAdvisor endpoint
--cert-dir="": The directory where the TLS certs are located (by default /var/run/kubernetes). If --tls-cert-file and --tls-private-key-file are provided, this flag will be ignored.
--cgroup-root="": Optional root cgroup to use for pods. This is handled by the container runtime on a best effort basis. Default: '', which means use the container runtime default.
--chaos-chance=0: If > 0.0, introduce random client errors and latency. Intended for testing. [default=0.0]
--cloud-config="": The path to the cloud provider configuration file. Empty string for no configuration file.
--cloud-provider="": The provider for cloud services. Empty string for no provider.
--cluster-dns=<nil>: IP address for a cluster DNS server. If set, kubelet will configure all containers to use this for DNS resolution in addition to the host's DNS servers
--cluster-domain="": Domain for this cluster. If set, kubelet will configure all containers to search this domain in addition to the host's search domains
--config="": Path to the config file or directory of files
--configure-cbr0=false: If true, kubelet will configure cbr0 based on Node.Spec.PodCIDR.
--container-runtime="": The container runtime to use. Possible values: 'docker', 'rkt'. Default: 'docker'.
--containerized=false: Experimental support for running kubelet in a container. Intended for testing. [default=false]
--docker-endpoint="": If non-empty, use this for the docker endpoint to communicate with
--docker-exec-handler="": Handler to use when executing a command in a container. Valid values are 'native' and 'nsenter'. Defaults to 'native'.
--enable-debugging-handlers=false: Enables server endpoints for log collection and local running of containers and commands
--enable-server=false: Enable the Kubelet's server
--file-check-frequency=0: Duration between checking config files for new data
--healthz-bind-address=<nil>: The IP address for the healthz server to serve on, defaulting to 127.0.0.1 (set to 0.0.0.0 for all interfaces)
--healthz-port=0: The port of the localhost healthz endpoint
-h, --help=false: help for kubelet
--host-network-sources="": Comma-separated list of sources from which the Kubelet allows pods to use of host network. For all sources use "*" [default="file"]
--hostname-override="": If non-empty, will use this string as identification instead of the actual hostname.
--http-check-frequency=0: Duration between checking http for new data
--image-gc-high-threshold=0: The percent of disk usage after which image garbage collection is always run. Default: 90%%
--image-gc-low-threshold=0: The percent of disk usage before which image garbage collection is never run. Lowest disk usage to garbage collect to. Default: 80%%
--kubeconfig=: Path to a kubeconfig file, specifying how to authenticate to API server (the master location is set by the api-servers flag).
--low-diskspace-threshold-mb=0: The absolute free disk space, in MB, to maintain. When disk space falls below this threshold, new pods would be rejected. Default: 256
--manifest-url="": URL for accessing the container manifest
--master-service-namespace="": The namespace from which the Kubernetes master services should be injected into pods
--max-pods=40: Number of Pods that can run on this Kubelet.
--maximum-dead-containers=0: Maximum number of old instances of a containers to retain globally. Each container takes up some disk space. Default: 100.
--maximum-dead-containers-per-container=0: Maximum number of old instances of a container to retain per container. Each container takes up some disk space. Default: 2.
--minimum-container-ttl-duration=0: Minimum age for a finished container before it is garbage collected. Examples: '300ms', '10s' or '2h45m'
--network-plugin="": <Warning: Alpha feature> The name of the network plugin to be invoked for various events in kubelet/pod lifecycle
--node-status-update-frequency=0: Specifies how often kubelet posts node status to master. Note: be cautious when changing the constant, it must work with nodeMonitorGracePeriod in nodecontroller. Default: 10s
--oom-score-adj=0: The oom_score_adj value for kubelet process. Values must be within the range [-1000, 1000]
--pod-cidr="": The CIDR to use for pod IP addresses, only used in standalone mode. In cluster mode, this is obtained from the master.
--pod-infra-container-image="": The image whose network/ipc namespaces containers in each pod will use.
--port=0: The port for the Kubelet to serve on. Note that "kubectl logs" will not work if you set this flag.
--read-only-port=0: The read-only port for the Kubelet to serve on (set to 0 to disable)
--really-crash-for-testing=false: If true, when panics occur crash. Intended for testing.
--register-node=false: Register the node with the apiserver (defaults to true if --api-server is set)
--registry-burst=0: Maximum size of a bursty pulls, temporarily allows pulls to burst to this number, while still not exceeding registry_qps. Only used if --registry-qps > 0
--registry-qps=0: If > 0, limit registry pull QPS to this value. If 0, unlimited. [default=0.0]
--resource-container="": Absolute name of the resource-only container to create and run the Kubelet in (Default: /kubelet).
--root-dir="": Directory path for managing kubelet files (volume mounts,etc).
--runonce=false: If true, exit after spawning pods from local manifests or remote urls. Exclusive with --api-servers, and --enable-server
--streaming-connection-idle-timeout=0: Maximum time a streaming connection can be idle before the connection is automatically closed. Example: '5m'
--sync-frequency=0: Max period between synchronizing running containers and config
--system-container="": Optional resource-only container in which to place all non-kernel processes that are not already in a container. Empty for no container. Rolling back the flag requires a reboot. (Default: "").
--tls-cert-file="": File containing x509 Certificate for HTTPS. (CA cert, if any, concatenated after server cert). If --tls-cert-file and --tls-private-key-file are not provided, a self-signed certificate and key are generated for the public address and saved to the directory passed to --cert-dir.
--tls-private-key-file="": File containing x509 private key matching --tls-cert-file.