13 KiB
13 KiB
kubelet
Synopsis
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 a 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.
kubelet
Options
--address=0.0.0.0: 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=4194: The port of the localhost cAdvisor endpoint
--cert-dir="/var/run/kubernetes": 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="": 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="docker": 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]
--cpu-cfs-quota[=true]: Enable CPU CFS quota enforcement for containers that specify CPU limits
--docker-endpoint="": If non-empty, use this for the docker endpoint to communicate with
--docker-exec-handler="native": Handler to use when executing a command in a container. Valid values are 'native' and 'nsenter'. Defaults to 'native'.
--enable-custom-metrics[=false]: Support for gathering custom metrics.
--enable-debugging-handlers[=true]: Enables server endpoints for log collection and local running of containers and commands
--enable-server[=true]: Enable the Kubelet's server
--event-burst=10: Maximum size of a bursty event records, temporarily allows event records to burst to this number, while still not exceeding event-qps. Only used if --event-qps > 0
--event-qps=5: If > 0, limit event creations per second to this value. If 0, unlimited.
--experimental-flannel-overlay[=false]: Experimental support for starting the kubelet with the default overlay network (flannel). Assumes flanneld is already running in client mode. [default=false]
--file-check-frequency=20s: Duration between checking config files for new data
--google-json-key="": The Google Cloud Platform Service Account JSON Key to use for authentication.
--hairpin-mode="promiscuous-bridge": How should the kubelet setup hairpin NAT. This allows endpoints of a Service to loadbalance back to themselves if they should try to access their own Service. Valid values are "promiscuous-bridge", "hairpin-veth" and "none".
--healthz-bind-address=127.0.0.1: 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=10248: The port of the localhost healthz endpoint
--host-ipc-sources="*": Comma-separated list of sources from which the Kubelet allows pods to use the host ipc namespace. [default="*"]
--host-network-sources="*": Comma-separated list of sources from which the Kubelet allows pods to use of host network. [default="*"]
--host-pid-sources="*": Comma-separated list of sources from which the Kubelet allows pods to use the host pid namespace. [default="*"]
--hostname-override="": If non-empty, will use this string as identification instead of the actual hostname.
--http-check-frequency=20s: Duration between checking http for new data
--image-gc-high-threshold=90: The percent of disk usage after which image garbage collection is always run. Default: 90%
--image-gc-low-threshold=80: The percent of disk usage before which image garbage collection is never run. Lowest disk usage to garbage collect to. Default: 80%
--kube-api-burst=10: Burst to use while talking with kubernetes apiserver
--kube-api-qps=5: QPS to use while talking with kubernetes apiserver
--kube-reserved=: A set of ResourceName=ResourceQuantity (e.g. cpu=200m,memory=150G) pairs that describe resources reserved for kubernetes system components. Currently only cpu and memory are supported. See http://releases.k8s.io/HEAD/docs/user-guide/compute-resources.md for more detail. [default=none]
--kubeconfig="/var/lib/kubelet/kubeconfig": Path to a kubeconfig file, specifying how to authenticate to API server (the master location is set by the api-servers flag).
--kubelet-cgroups="": Optional absolute name of cgroups to create and run the Kubelet in.
--lock-file="": <Warning: Alpha feature> The path to file for kubelet to use as a lock file.
--log-flush-frequency=5s: Maximum number of seconds between log flushes
--low-diskspace-threshold-mb=256: 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
--manifest-url-header="": HTTP header to use when accessing the manifest URL, with the key separated from the value with a ':', as in 'key:value'
--master-service-namespace="default": The namespace from which the kubernetes master services should be injected into pods
--max-open-files=1000000: Number of files that can be opened by Kubelet process. [default=1000000]
--max-pods=110: Number of Pods that can run on this Kubelet.
--maximum-dead-containers=240: Maximum number of old instances of containers to retain globally. Each container takes up some disk space. Default: 100.
--maximum-dead-containers-per-container=2: Maximum number of old instances to retain per container. Each container takes up some disk space. Default: 2.
--minimum-container-ttl-duration=1m0s: Minimum age for a finished container before it is garbage collected. Examples: '300ms', '10s' or '2h45m'
--minimum-image-ttl-duration=2m0s: Minimum age for a unused image before it is garbage collected. Examples: '300ms', '10s' or '2h45m'. Default: '2m'
--network-plugin="": <Warning: Alpha feature> The name of the network plugin to be invoked for various events in kubelet/pod lifecycle
--network-plugin-dir="/usr/libexec/kubernetes/kubelet-plugins/net/exec/": <Warning: Alpha feature> The full path of the directory in which to search for network plugins
--node-ip="": IP address of the node. If set, kubelet will use this IP address for the node
--node-labels=: <Warning: Alpha feature> Labels to add when registering the node in the cluster. Labels must be key=value pairs separated by ','.
--node-status-update-frequency=10s: 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
--non-masquerade-cidr="10.0.0.0/8": Traffic to IPs outside this range will use IP masquerade.
--oom-score-adj=-999: The oom-score-adj value for kubelet process. Values must be within the range [-1000, 1000]
--outofdisk-transition-frequency=5m0s: Duration for which the kubelet has to wait before transitioning out of out-of-disk node condition status. Default: 5m0s
--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="gcr.io/google_containers/pause:2.0": The image whose network/ipc namespaces containers in each pod will use.
--port=10250: The port for the Kubelet to serve on.
--read-only-port=10255: The read-only port for the Kubelet to serve on with no authentication/authorization (set to 0 to disable)
--really-crash-for-testing[=false]: If true, when panics occur crash. Intended for testing.
--reconcile-cidr[=true]: Reconcile node CIDR with the CIDR specified by the API server. No-op if register-node or configure-cbr0 is false. [default=true]
--register-node[=true]: Register the node with the apiserver (defaults to true if --api-servers is set)
--register-schedulable[=true]: Register the node as schedulable. No-op if register-node is false. [default=true]
--registry-burst=10: 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=5: If > 0, limit registry pull QPS to this value. If 0, unlimited. [default=5.0]
--resolv-conf="/etc/resolv.conf": Resolver configuration file used as the basis for the container DNS resolution configuration.
--rkt-path="": Path of rkt binary. Leave empty to use the first rkt in $PATH. Only used if --container-runtime='rkt'
--rkt-stage1-image="": image to use as stage1. Local paths and http/https URLs are supported. If empty, the 'stage1.aci' in the same directory as '--rkt-path' will be used
--root-dir="/var/lib/kubelet": 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
--runtime-cgroups="": Optional absolute name of cgroups to create and run the runtime in.
--serialize-image-pulls[=true]: Pull images one at a time. We recommend *not* changing the default value on nodes that run docker daemon with version < 1.9 or an Aufs storage backend. Issue #10959 has more details. [default=true]
--streaming-connection-idle-timeout=4h0m0s: Maximum time a streaming connection can be idle before the connection is automatically closed. 0 indicates no timeout. Example: '5m'
--sync-frequency=1m0s: Max period between synchronizing running containers and config
--system-cgroups="": Optional absolute name of cgroups in which to place all non-kernel processes that are not already inside a cgroup under `/`. Empty for no container. Rolling back the flag requires a reboot. (Default: "").
--system-reserved=: A set of ResourceName=ResourceQuantity (e.g. cpu=200m,memory=150G) pairs that describe resources reserved for non-kubernetes components. Currently only cpu and memory are supported. See http://releases.k8s.io/HEAD/docs/user-guide/compute-resources.md for more detail. [default=none]
--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.
--volume-plugin-dir="/usr/libexec/kubernetes/kubelet-plugins/volume/exec/": <Warning: Alpha feature> The full path of the directory in which to search for additional third party volume plugins
--volume-stats-agg-period=1m0s: Specifies interval for kubelet to calculate and cache the volume disk usage for all pods and volumes. To disable volume calculations, set to 0. Default: '1m'