{"record":{"id":"aabaafe67e509f96","repo":"kubernetes/kubernetes","slug":"unable-to-get-hostname-v","errorCode":null,"errorMessage":"unable to get hostname: %v","messagePattern":"unable to get hostname: (.+?)","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"cmd/kube-scheduler/app/options/options.go","lineNumber":356,"sourceCode":"\t\t}\n\t}\n\n\tc.Client = client\n\tc.InformerFactory = scheduler.NewInformerFactory(client, 0, o.InformerName)\n\tdynClient := dynamic.NewForConfigOrDie(c.KubeConfig)\n\tc.DynInformerFactory = dynamicinformer.NewFilteredDynamicSharedInformerFactory(dynClient, 0, corev1.NamespaceAll, nil)\n\tc.LeaderElection = leaderElectionConfig\n\tc.ComponentGlobalsRegistry = o.ComponentGlobalsRegistry\n\n\treturn c, nil\n}\n\n// makeLeaderElectionConfig builds a leader election configuration. It will\n// create a new resource lock associated with the configuration.\nfunc makeLeaderElectionConfig(config componentbaseconfig.LeaderElectionConfiguration, kubeConfig *restclient.Config, recorder record.EventRecorder) (*leaderelection.LeaderElectionConfig, error) {\n\thostname, err := os.Hostname()\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"unable to get hostname: %v\", err)\n\t}\n\t// add a uniquifier so that two processes on the same host don't accidentally both become active\n\tid := hostname + \"_\" + string(uuid.NewUUID())\n\n\trl, err := resourcelock.NewFromKubeconfig(config.ResourceLock,\n\t\tconfig.ResourceNamespace,\n\t\tconfig.ResourceName,\n\t\tresourcelock.ResourceLockConfig{\n\t\t\tIdentity:      id,\n\t\t\tEventRecorder: recorder,\n\t\t},\n\t\tkubeConfig,\n\t\tconfig.RenewDeadline.Duration)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"couldn't create resource lock: %v\", err)\n\t}\n\n\treturn &leaderelection.LeaderElectionConfig{","sourceCodeStart":338,"sourceCodeEnd":374,"githubUrl":"https://github.com/kubernetes/kubernetes/blob/b882c60b4023bdf09264c2d5d30a2cadebc240fb/cmd/kube-scheduler/app/options/options.go#L338-L374","documentation":"In makeLeaderElectionConfig, the scheduler obtains the OS hostname via os.Hostname() to build a unique leader election identity (hostname + UUID). If the kernel returns an error from the hostname syscall, the function wraps it with this message and returns.","triggerScenarios":"Calling makeLeaderElectionConfig when the OS hostname is unreadable. os.Hostname() can fail on systems where the hostname is not set, the node is in an invalid state, or the syscall is denied by a security policy (e.g., seccomp).","commonSituations":"Container with a restricted seccomp profile that blocks the uname/gethostname syscall, a broken /proc or hostname configuration, or a node that has not yet been assigned a hostname during early boot.","solutions":["Set a hostname explicitly on the node/container: `hostnamectl set-hostname <name>` or set the `HOSTNAME` env / `--hostname-override` in the container runtime.","Relax the seccomp/security profile to allow hostname syscalls.","Investigate the underlying os.Hostname() error to determine if it is a filesystem, kernel, or policy issue."],"exampleFix":"// before — os.Hostname() fails in restricted container\nhostname, err := os.Hostname()\nif err != nil {\n    return nil, fmt.Errorf(\"unable to get hostname: %v\", err)\n}\n\n// after — allow override from env for restricted environments\nhostname := os.Getenv(\"HOSTNAME\")\nif hostname == \"\" {\n    hostname, err = os.Hostname()\n    if err != nil {\n        return nil, fmt.Errorf(\"unable to get hostname: %v\", err)\n    }\n}","handlingStrategy":"try-catch","validationCode":"// Pre-check hostname availability\nfunc validateHostname() error {\n    _, err := os.Hostname()\n    if err != nil {\n        // Try env fallback\n        if os.Getenv(\"HOSTNAME\") == \"\" {\n            return fmt.Errorf(\"hostname unavailable and HOSTNAME env not set: %w\", err)\n        }\n    }\n    return nil\n}","typeGuard":null,"tryCatchPattern":"hostname, err := os.Hostname()\nif err != nil {\n    // Fallback: use env var or node name from kubelet\n    hostname = os.Getenv(\"HOSTNAME\")\n    if hostname == \"\" {\n        return nil, fmt.Errorf(\"unable to get hostname: %v\", err)\n    }\n    klog.Warningf(\"os.Hostname() failed, using HOSTNAME env: %s\", hostname)\n}","preventionTips":["Set HOSTNAME environment variable in container specs as a fallback.","Allow seccomp profiles to permit hostname syscalls in scheduler pods.","Use --hostname-override or equivalent to provide a deterministic identity."],"tags":["kube-scheduler","hostname","leader-election","os","container"],"analyzedSha":"b882c60b4023bdf09264c2d5d30a2cadebc240fb","analyzedAt":"2026-08-07T04:07:48.144Z","schemaVersion":2},"datasetVersion":"2026-08-07T07:17:06.508Z"}