{"record":{"id":"102249c0914d7f2e","repo":"ahmetb/kubectx","slug":"failed-to-parse-server-url-q-w","errorCode":null,"errorMessage":"failed to parse server URL %q: %w","messagePattern":"failed to parse server URL %q: %w","errorType":"console","errorClass":null,"httpStatus":null,"severity":"error","filePath":"internal/proxy/readonly.go","lineNumber":73,"sourceCode":"\tContextName    string\n}\n\n// Start creates and starts a readonly reverse proxy on a random localhost port.\n// The proxy loads TLS/auth config from the kubeconfig and forwards only\n// GET, HEAD, and OPTIONS requests (without protocol upgrades) to the real API server.\nfunc Start(cfg Config) (*ReadonlyProxy, error) {\n\tloadingRules := &clientcmd.ClientConfigLoadingRules{ExplicitPath: cfg.KubeconfigPath}\n\toverrides := &clientcmd.ConfigOverrides{CurrentContext: cfg.ContextName}\n\tclientConfig := clientcmd.NewNonInteractiveDeferredLoadingClientConfig(loadingRules, overrides)\n\n\trestCfg, err := clientConfig.ClientConfig()\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to load kubeconfig: %w\", err)\n\t}\n\n\ttargetURL, err := url.Parse(restCfg.Host)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to parse server URL %q: %w\", restCfg.Host, err)\n\t}\n\n\ttransport, err := rest.TransportFor(restCfg)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to create transport: %w\", err)\n\t}\n\n\thandler := NewHandler(targetURL, transport)\n\n\tlistener, err := net.Listen(\"tcp\", \"127.0.0.1:0\")\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to listen: %w\", err)\n\t}\n\n\tsrv := &http.Server{Handler: handler}\n\tgo srv.Serve(listener)\n\n\tdebugLog.Printf(\"started on %s, proxying to %s\", listener.Addr(), targetURL)","sourceCodeStart":55,"sourceCodeEnd":91,"githubUrl":"https://github.com/ahmetb/kubectx/blob/12ad6fb22e8c546ee2b54e7de38aa51c906832f7/internal/proxy/readonly.go#L55-L91","documentation":"After loading the rest config, Start parses restCfg.Host (the API server address taken from the kubeconfig's cluster server field) with url.Parse. This error wraps a url.Parse failure and quotes the offending host string. It indicates the server address stored in the kubeconfig is not a parseable URL.","triggerScenarios":"Calling Start when the selected cluster's server field contains a malformed URL — e.g. missing scheme with invalid characters, whitespace, control characters, or other strings that violate RFC 3986 parsing rules.","commonSituations":"Hand-edited kubeconfig with a typo'd server value (stray space, unescaped characters); a cluster entry generated by tooling with an empty or placeholder server; shell interpolation mangling the value (unexpanded variable, truncated IPv6 address without brackets).","solutions":["Inspect the quoted host in the error message and fix the cluster's server field: kubectl config set-cluster <name> --server=https://<host>:6443","Ensure the server URL includes a scheme (https://) and a valid host; wrap bare IPv6 addresses in brackets","Re-generate the kubeconfig from the cluster (kubeadm/minikube/kind) if it was hand-edited badly","Pre-validate in code: parse the server field yourself before Start to produce a clearer failure"],"exampleFix":"// before\n// kubeconfig cluster:\n//   server: 10.0.0 5:6443\n// after\n//   server: https://10.0.0.5:6443","handlingStrategy":"validation","validationCode":"// Go\n// Pre-validate the cluster server URL before Start\nraw, _ := os.ReadFile(cfg.KubeconfigPath)\nparsed, err := clientcmd.Load(raw)\nif err != nil { return err }\nctxName := cfg.ContextName\nif ctxName == \"\" { ctxName = parsed.CurrentContext }\ncl := parsed.Contexts[ctxName].Cluster\nsrv := parsed.Clusters[cl].Server\nif u, err := url.Parse(srv); err != nil || u.Host == \"\" {\n    return fmt.Errorf(\"cluster %q has invalid server %q\", cl, srv)\n}","typeGuard":null,"tryCatchPattern":"if err := start(); err != nil {\n    if strings.Contains(err.Error(), \"failed to parse server URL\") {\n        var uerr *url.Error\n        if errors.As(err, &uerr) {\n            return fmt.Errorf(\"fix cluster server field (%v): %w\", uerr.URL, err)\n        }\n    }\n    return err\n}","preventionTips":["Always set the server field with kubectl config set-cluster instead of hand-editing","Ensure https:// scheme and a valid host:port; bracket bare IPv6 addresses","Avoid shell interpolation in kubeconfig values (unexpanded $VAR stays literal)","Re-generate kubeconfigs from the cluster after accidental manual edits"],"tags":["kubeconfig","url-parsing","configuration","go"],"backgroundTag":"invalid-server-url","analyzedSha":"12ad6fb22e8c546ee2b54e7de38aa51c906832f7","analyzedAt":"2026-09-02T12:23:10.107Z","contentChangedAt":null,"schemaVersion":2},"datasetVersion":"2026-09-09T16:17:10.729Z"}