kubelet man page
kubelet — Processes a container manifest so the containers are launched according to how they are described. 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. The kubelet doesn't manage containers which were not created by Kubernetes. 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. kubelet /usr/bin/kubelet --logtostderr=true --v=0 --api_servers= ⟨http://127.0.0.1:8080⟩ --address=127.0.0.1 --port=10250 --hostname_override=127.0.0.1 --allow-privileged=false
--address ip The IP address for the Kubelet to serve on (set to 0.0.0.0 for all interfaces) (default 0.0.0.0)
--allow-privileged If true, allow containers to request privileged mode. [default=false]
--authentication-token-webhook Use the TokenReview API to determine authentication for bearer tokens.
--authentication-token-webhook-cache-ttl duration The duration to cache responses from the webhook token authenticator. (default 2m0s)
--authorization-mode string Authorization mode for Kubelet server. Valid options are AlwaysAllow or Webhook. Webhook mode uses the SubjectAccessReview API to determine authorization. (default "AlwaysAllow")
--authorization-webhook-cache-authorized-ttl duration The duration to cache 'authorized' responses from the webhook authorizer. (default 5m0s)
--authorization-webhook-cache-unauthorized-ttl duration The duration to cache 'unauthorized' responses from the webhook authorizer. (default 30s)
--azure-container-registry-config string Path to the file container Azure container registry configuration information.
--cadvisor-port int32 The port of the localhost cAdvisor endpoint (default 4194)
--cert-dir string 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. (default "/var/run/kubernetes")
--chaos-chance float If > 0.0, introduce random client errors and latency. Intended for testing. [default=0.0]
--client-ca-file string If set, any request presenting a client certificate signed by one of the authorities in the client-ca-file is authenticated with an identity corresponding to the CommonName of the client certificate.
--cloud-config string The path to the cloud provider configuration file. Empty string for no configuration file.
--cloud-provider string The provider for cloud services. By default, kubelet will attempt to auto-detect the cloud provider. Specify empty string for running with no cloud provider. [default=auto-detect] (default "auto-detect")
--cluster-dns string IP address for a cluster DNS server. This value is used for containers' DNS server in case of Pods with "dnsPolicy=ClusterFirst"
--cluster-domain string Domain for this cluster. If set, kubelet will configure all containers to search this domain in addition to the host's search domains
--container-runtime-endpoint string [Experimental] The unix socket endpoint of remote runtime service. The endpoint is used only when CRI integration is enabled (--experimental-cri)
--containerized Experimental support for running kubelet in a container. Intended for testing. [default=false]
--cpu-cfs-quota Enable CPU CFS quota enforcement for containers that specify CPU limits (default true)
--docker-endpoint string Use this for the docker endpoint to communicate with (default "unix:///var/run/docker.sock")
--docker-exec-handler string Handler to use when executing a command in a container. Valid values are 'native' and 'nsenter'. Defaults to 'native'. (default "native")
--enable-controller-attach-detach Enables the Attach/Detach controller to manage attachment/detachment of volumes scheduled to this node, and disables kubelet from executing any attach/detach operations (default true)
--enable-custom-metrics Support for gathering custom metrics.
--enable-debugging-handlers Enables server endpoints for log collection and local running of containers and commands (default true)
--enable-server Enable the Kubelet's server (default true)
--event-burst int32 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 (default 10)
--event-qps int32 If > 0, limit event creations per second to this value. If 0, unlimited. (default 5)
--eviction-hard string A set of eviction thresholds (e.g. memory.available<1Gi) that if met would trigger a pod eviction. (default "memory.available<100Mi")
--eviction-max-pod-grace-period int32 Maximum allowed grace period (in seconds) to use when terminating pods in response to a soft eviction threshold being met. If negative, defer to pod specified value.
--eviction-minimum-reclaim string A set of minimum reclaims (e.g. imagefs.available=2Gi) that describes the minimum amount of resource the kubelet will reclaim when performing a pod eviction if that resource is under pressure.
--eviction-pressure-transition-period duration Duration for which the kubelet has to wait before transitioning out of an eviction pressure condition. (default 5m0s)
--eviction-soft string A set of eviction thresholds (e.g. memory.available<1.5Gi) that if met over a corresponding grace period would trigger a pod eviction.
--eviction-soft-grace-period string A set of eviction grace periods (e.g. memory.available=1m30s) that correspond to how long a soft eviction threshold must hold before triggering a pod eviction.
--exit-on-lock-contention Whether kubelet should exit upon lock-file contention.
--experimental-allowed-unsafe-sysctls stringSlice Comma-separated whitelist of unsafe sysctls or unsafe sysctl patterns (ending in *). Use these at your own risk.
--experimental-cgroups-per-qos Enable creation of QoS cgroup hierarchy, if true top level QoS and pod cgroups are created.
--experimental-check-node-capabilities-before-mount [Experimental] if set true, the kubelet will check the underlying node for required componenets (binaries, etc.) before performing the mount
--experimental-cri [Experimental] Enable the Container Runtime Interface (CRI) integration. If --container-runtime is set to "remote", Kubelet will communicate with the runtime/image CRI server listening on the endpoint specified by --remote-runtime-endpoint/--remote-image-endpoint. If --container-runtime is set to "docker", Kubelet will launch a in-process CRI server on behalf of docker, and communicate over a default endpoint.
--experimental-fail-swap-on Makes the Kubelet fail to start if swap is enabled on the node. This is a temporary opton to maintain legacy behavior, failing due to swap enabled will happen by default in v1.6.
--experimental-kernel-memcg-notification If enabled, the kubelet will integrate with the kernel memcg notification to determine if memory eviction thresholds are crossed rather than polling.
--experimental-mounter-path string [Experimental] Path of mounter binary. Leave empty to use the default mount.
--experimental-nvidia-gpus int32 Number of NVIDIA GPU devices on this node. Only 0 (default) and 1 are currently supported.
--file-check-frequency duration Duration between checking config files for new data (default 20s)
--google-json-key string The Google Cloud Platform Service Account JSON Key to use for authentication.
--hairpin-mode string 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". (default "promiscuous-bridge")
--healthz-bind-address ip 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) (default 127.0.0.1)
--healthz-port int32 The port of the localhost healthz endpoint (default 10248)
--host-ipc-sources stringSlice Comma-separated list of sources from which the Kubelet allows pods to use the host ipc namespace. ⟨default [*]⟩
--host-network-sources stringSlice Comma-separated list of sources from which the Kubelet allows pods to use of host network. ⟨default [*]⟩
--host-pid-sources stringSlice Comma-separated list of sources from which the Kubelet allows pods to use the host pid namespace. ⟨default [*]⟩
--hostname-override string If non-empty, will use this string as identification instead of the actual hostname.
--http-check-frequency duration Duration between checking http for new data (default 20s) --image-gc-high-threshold int32 The percent of disk usage after which image garbage collection is always run. Default
90% (default 90)
--image-service-endpoint string [Experimental] The unix socket endpoint of remote image service. If not specified, it will be the same with container-runtime-endpoint by default. The endpoint is used only when CRI integration is enabled (--experimental-cri)
--iptables-drop-bit int32 The bit of the fwmark space to mark packets for dropping. Must be within the range [0, 31]. (default 15)
--iptables-masquerade-bit int32 The bit of the fwmark space to mark packets for SNAT. Must be within the range [0, 31]. Please match this parameter with corresponding parameter in kube-proxy. (default 14)
--kube-api-burst int32 Burst to use while talking with kubernetes apiserver (default 10)
--kube-api-content-type string Content type of requests sent to apiserver. (default "application/vnd.kubernetes.protobuf")
--kube-api-qps int32 QPS to use while talking with kubernetes apiserver (default 5)
--kubeconfig string Path to a kubeconfig file, specifying how to connect to the API server. --api-servers will be used for the location unless --require-kubeconfig is set. (default "/var/lib/kubelet/kubeconfig")
--kubelet-cgroups string Optional absolute name of cgroups to create and run the Kubelet in.
--make-iptables-util-chains If true, kubelet will ensure iptables utility rules are present on host. (default true)
--manifest-url string URL for accessing the container manifest
--master-service-namespace string The namespace from which the kubernetes master services should be injected into pods (default "default")
--max-open-files int Number of files that can be opened by Kubelet process. [default=1000000] (default 1000000)
--max-pods int32 Number of Pods that can run on this Kubelet. (default 110)
--node-ip string IP address of the node. If set, kubelet will use this IP address for the node
--non-masquerade-cidr string Traffic to IPs outside this range will use IP masquerade. (default "10.0.0.0/8")
--oom-score-adj int32 The oom-score-adj value for kubelet process. Values must be within the range [-1000, 1000] (default -999)
--pod-cidr string 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 string The image whose network/ipc namespaces containers in each pod will use. (default "gcr.io/google_containers/pause-amd64:3.0")
--pod-manifest-path string Path to to the directory containing pod manifest files to run, or the path to a single pod manifest file.
--pods-per-core int32 Number of Pods per core that can run on this Kubelet. The total number of Pods on this Kubelet cannot exceed max-pods, so max-pods will be used if this calculation results in a larger number of Pods allowed on the Kubelet. A value of 0 disables this limit.
--port int32 The port for the Kubelet to serve on. (default 10250)
--protect-kernel-defaults Default kubelet behaviour for kernel tuning. If set, kubelet errors if any of kernel tunables is different than kubelet defaults.
--read-only-port int32 The read-only port for the Kubelet to serve on with no authentication/authorization (set to 0 to disable) (default 10255)
--really-crash-for-testing If true, when panics occur crash. Intended for testing.
--register-node Register the node with the apiserver (defaults to true if --api-servers is set) (default true)
--register-schedulable Register the node as schedulable. Won't have any effect if register-node is false. [default=true] (default true)
--registry-burst int32 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 (default 10)
--registry-qps int32 If > 0, limit registry pull QPS to this value. If 0, unlimited. [default=5.0] (default 5)
--require-kubeconfig If true the Kubelet will exit if there are configuration errors, and will ignore the value of --api-servers in favor of the server defined in the kubeconfig file.
--resolv-conf string Resolver configuration file used as the basis for the container DNS resolution configuration. (default "/etc/resolv.conf")
--rkt-api-endpoint string The endpoint of the rkt API service to communicate with. Only used if --container-runtime='rkt'. (default "localhost:15441")
--rkt-path string Path of rkt binary. Leave empty to use the first rkt in $PATH. Only used if --container-runtime='rkt'.
--root-dir string Directory path for managing kubelet files (volume mounts,etc). (default "/var/lib/kubelet")
--runonce If true, exit after spawning pods from local manifests or remote urls. Exclusive with --api-servers, and --enable-server
--runtime-cgroups string Optional absolute name of cgroups to create and run the runtime in.
--seccomp-profile-root string Directory path for seccomp profiles. (default "/var/lib/kubelet/seccomp")
--serialize-image-pulls 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] (default true)
--sync-frequency duration Max period between synchronizing running containers and config (default 1m0s)
--tls-cert-file string 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 string File containing x509 private key matching --tls-cert-file.
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. The kubelet doesn't manage containers which were not created by Kubernetes.
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.
/usr/bin/kubelet --logtostderr=true --v=0 --api_servers= ⟨http://127.0.0.1:8080⟩ --address=127.0.0.1 --port=10250 --hostname_override=127.0.0.1 --allow-privileged=false