{"record":{"id":"6af8c1fbc387fa4d","repo":"kubernetes/kops","slug":"encoding-kubelet-component-config-w","errorCode":null,"errorMessage":"encoding kubelet component config: %w","messagePattern":"encoding kubelet component config: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"nodeup/pkg/model/kubelet.go","lineNumber":292,"sourceCode":"\t\t\tc.EnsureTask(b.buildCgroupService(cgroup))\n\t\t}\n\t}\n\t*/\n\n\tc.AddTask(b.buildSystemdService())\n\n\treturn nil\n}\n\nfunc (b *KubeletBuilder) buildKubeletComponentConfig(kubeletConfig *kops.KubeletConfigSpec, providerID string) (*nodetasks.File, error) {\n\tcomponentConfig, err := b.kubeletConfiguration(kubeletConfig, providerID)\n\tif err != nil {\n\t\treturn nil, err\n\t}\n\n\tvar buf bytes.Buffer\n\tif err := kubeletV1Beta1Encoder.Encode(componentConfig, &buf); err != nil {\n\t\treturn nil, fmt.Errorf(\"encoding kubelet component config: %w\", err)\n\t}\n\n\treturn &nodetasks.File{\n\t\tPath:           kubeletConfigFilePath,\n\t\tContents:       fi.NewBytesResource(buf.Bytes()),\n\t\tType:           nodetasks.FileType_File,\n\t\tBeforeServices: []string{kubeletService},\n\t}, nil\n}\n\n// kubeletConfiguration translates a kops.KubeletConfigSpec into the upstream\n// kubelet.KubeletConfiguration written to /var/lib/kubelet/kubelet.conf.\n// Most kubelet CLI flags are deprecated upstream in favor of this config\n// file; fields that have flag:\"-\" in the kops API land here.\nfunc (b *KubeletBuilder) kubeletConfiguration(kubeletConfig *kops.KubeletConfigSpec, providerID string) (*kubelet.KubeletConfiguration, error) {\n\tcc := &kubelet.KubeletConfiguration{\n\t\tCgroupDriver:                     kubeletConfig.CgroupDriver,\n\t\tCgroupRoot:                       kubeletConfig.CgroupRoot,","sourceCodeStart":274,"sourceCodeEnd":310,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/nodeup/pkg/model/kubelet.go#L274-L310","documentation":"This error wraps any failure from the kubelet v1beta1 config encoder while serializing the KubeletConfigSpec into the kubelet component config YAML that nodeup writes to kubeletConfigFilePath. The kubelet configuration must be valid kubescheduler-style v1beta1 YAML; if any field in the assembled componentConfig cannot be encoded (schema mismatch, invalid value type), the encode call fails and the underlying encoder error is wrapped with this message.","triggerScenarios":"buildKubeletComponentConfig -> kubeletV1Beta1Encoder.Encode(componentConfig, &buf) returns an error, typically because a field set on the KubeletComponentConfiguration is not representable in the v1beta1 kubelet config schema.","commonSituations":"Using a kops feature that sets a kubelet config field unsupported by the installed Kubernetes version's v1beta1 schema; nil/invalid nested config values assembled in kubeletConfiguration; kops code drift where a field was populated that the encoder cannot marshal.","solutions":["Read the wrapped underlying error (%w) to find which config field failed to encode","Compare the offending field against the kubelet v1beta1 KubeletConfiguration schema for your Kubernetes version","Remove or correct the unsupported field in the cluster spec (kops edit cluster / instancegroup)","Upgrade or align the kops version with the target Kubernetes version and rebuild nodeup"],"exampleFix":"// before (spec with unsupported field)\nkubeletConfig.CpuManagerPolicy = \"static\"\n// after (remove or guard field unsupported by the encoder/schema)\nkops delete cluster --yes # then recreate spec without the invalid field, or:\nkops edit cluster # remove kubelet.cpuManagerPolicy","handlingStrategy":"try-catch","validationCode":"// Marshal a dry-run copy with the same encoder before applying\nvar buf bytes.Buffer\nif err := kubeletV1Beta1Encoder.Encode(componentConfig, &buf); err != nil {\n    return fmt.Errorf(\"kubelet component config would fail to encode: %w\", err)\n}","typeGuard":null,"tryCatchPattern":"if err := buildKubeletComponentConfig(...); err != nil {\n    var encErr *encodingError\n    if errors.As(err, &encErr) { log.Errorf(\"kubelet config encode failed: %v\", encErr) }\n    return err\n}","preventionTips":["Keep kops and Kubernetes versions aligned so all populated fields exist in the v1beta1 schema","Dry-run encode the component config in CI before shipping nodeup changes","Avoid populating experimental kubelet fields unsupported by your target version"],"tags":["kubelet","config-encoding","nodeup"],"backgroundTag":"kubelet-config-encode-failed","analyzedSha":"4c8573c808a73d578c5eadc86d410646ea0b0d73","analyzedAt":"2026-09-05T04:13:19.212Z","contentChangedAt":"2026-09-05T04:13:19.212Z","schemaVersion":2},"datasetVersion":"2026-09-12T07:17:12.445Z"}