[[["わかりやすい","easyToUnderstand","thumb-up"],["問題の解決に役立った","solvedMyProblem","thumb-up"],["その他","otherUp","thumb-up"]],[["わかりにくい","hardToUnderstand","thumb-down"],["情報またはサンプルコードが不正確","incorrectInformationOrSampleCode","thumb-down"],["必要な情報 / サンプルがない","missingTheInformationSamplesINeed","thumb-down"],["翻訳に関する問題","translationIssue","thumb-down"],["その他","otherDown","thumb-down"]],["最終更新日 2025-05-08 UTC。"],[],[],null,["# Reserved hostPorts\n\n[Autopilot](/kubernetes-engine/docs/concepts/autopilot-overview) [Standard](/kubernetes-engine/docs/concepts/choose-cluster-mode)\n\n*** ** * ** ***\n\nThis page describes the list of reserved hostPorts within\nGoogle Kubernetes Engine (GKE).\n| **Note:** Always refer to the latest GKE release notes for any updates or changes to GKE's reserved hostPort ranges. When in doubt, avoid using hostPorts and rely on Kubernetes service abstractions.\n\nGKE System reserved hostPorts\n-----------------------------\n\nGKE reserves specific `hostPort` ranges for its internal system\nprocesses and services. These reservations are crucial for maintaining the\nstability and functionality of GKE clusters. Although\nGKE generally discourages the use of `hostPort` for user\napplications due to potential conflicts and security risks, it relies on them\nfor internal operations.\n| **Warning:** Attempting to use hostPorts within GKE's reserved ranges might result in Pod deployment failures or unexpected cluster behavior. GKE reserves the right to change these ranges without prior notice.\n\n### Purpose of reserved hostPorts\n\n- **Control plane communication**: certain GKE components, such as the kubelet and metrics-server, might use specific hostPorts for communication with the control plane or other internal services.\n- **System daemons**: GKE system daemons and agents might require access to specific ports on the nodes for monitoring, logging, or other operational tasks.\n- **Internal services**: GKE's internal services, responsible for cluster management and health checks, might use reserved hostPorts.\n\n### Understanding reserved ranges\n\nAlthough the exact ranges can vary based on GKE version and\nconfiguration, GKE\nreserves a portion of the available port space. These reserved ranges are\ntypically not documented for external user usage, as they are subject to change.\nIt is very important to avoid using low-numbered ports, as these are commonly\nreserved by operating systems.\n\n### Best practices\n\n**Best practices**:\n\n- **Avoid hostPort usage**: minimize the use of hostPort in your application deployments to reduce the risk of conflicts with GKE's reserved ports.\n- **Service abstractions**: use Kubernetes service types (NodePort, LoadBalancer, Ingress) as preferred alternatives to hostPort.\n- **Security scrutiny**: if hostPort is unavoidable, carefully review and implement firewall rules to restrict access to the exposed ports.\n- **Autopilot considerations**: when you use GKE Autopilot, be aware that you are unable to specify exact hostPorts.\n\n### List of reserved hostPorts\n\n### List of reserved hostPorts that are specific to Autopilot\n\nWhat's next\n-----------\n\n- Read an overview of [networking in\n GKE](/kubernetes-engine/docs/concepts/network-overview).\n- Learn about [Kubernetes Services](/kubernetes-engine/docs/concepts/service).\n- Learn about [exposing\n applications](/kubernetes-engine/docs/how-to/exposing-apps)."]]
