{"record":{"id":"6763d04ac27a870a","repo":"kubernetes/kops","slug":"error-dialing-target-q-w","errorCode":null,"errorMessage":"error dialing target %q: %w","messagePattern":"error dialing target %q: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/bootstrap/challenge_client.go","lineNumber":115,"sourceCode":"\ttlsConfig := &tls.Config{\n\t\tRootCAs:      serverCAs,\n\t\tCertificates: []tls.Certificate{*clientCertificate},\n\t\tServerName:   serverName,\n\t}\n\n\tkospControllerNonce := randomBytes(16)\n\treq := &pb.ChallengeRequest{\n\t\tChallengeId:     challenge.ChallengeID,\n\t\tChallengeRandom: kospControllerNonce,\n\t}\n\n\texpectedChallengeResponse := buildChallengeResponse(challenge.ChallengeSecret, kospControllerNonce)\n\n\tvar opts []grpc.DialOption\n\topts = append(opts, grpc.WithTransportCredentials(credentials.NewTLS(tlsConfig)))\n\tconn, err := grpc.DialContext(ctx, targetEndpoint, opts...)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"error dialing target %q: %w\", targetEndpoint, err)\n\t}\n\tdefer conn.Close()\n\tclient := pb.NewCallbackServiceClient(conn)\n\n\tresponse, err := client.Challenge(ctx, req)\n\tif err != nil {\n\t\treturn fmt.Errorf(\"error from callback challenge: %w\", err)\n\t}\n\n\tif subtle.ConstantTimeCompare(response.GetChallengeResponse(), expectedChallengeResponse) != 1 {\n\t\treturn fmt.Errorf(\"callback challenge returned wrong result\")\n\t}\n\treturn nil\n}\n","sourceCodeStart":97,"sourceCodeEnd":130,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/pkg/bootstrap/challenge_client.go#L97-L130","documentation":"This wraps any failure from grpc.DialContext when establishing the gRPC connection to the kops-controller callback endpoint. Because the TLS config uses a custom RootCAs and client certificate, failures include DNS resolution errors, TCP connection refused/timeout, and TLS handshake failures — all reported under this single wrapper with the target address quoted.","triggerScenarios":"Calling DoCallbackChallenge when the endpoint host is unresolvable, the kops-controller service is not listening on the target port, a firewall/security group blocks the port, or the client certificate/server CA mismatch causes a TLS handshake abort.","commonSituations":"Wrong endpoint host:port in challenge config; kops-controller not running or scaling down; NetworkPolicy/security-group rules blocking node-to-controller traffic; clock skew or CA mismatch breaking the TLS handshake.","solutions":["Verify the endpoint host resolves and the kops-controller port is reachable from the node (nc/test connection)","Confirm kops-controller pods are running and the service is exposed","Check network policies and cloud security groups allow node -> controller traffic on the callback port","Confirm Challenge.ServerCA actually signed the controller's serving cert"],"exampleFix":"null","handlingStrategy":"retry","validationCode":"host, port, _ := net.SplitHostPort(strings.TrimPrefix(ch.Endpoint, \"https://\"))\nif _, err := net.LookupHost(host); err != nil {\n\treturn fmt.Errorf(\"endpoint host %q does not resolve\", host)\n}\nif conn, err := net.DialTimeout(\"tcp\", net.JoinHostPort(host, port), 5*time.Second); err != nil {\n\treturn fmt.Errorf(\"endpoint %s not reachable: %w\", ch.Endpoint, err)\n} else { conn.Close() }","typeGuard":null,"tryCatchPattern":"err := backoff.Retry(func() error {\n\treturn client.DoCallbackChallenge(ctx, clusterName, ch)\n}, backoff.WithMaxRetries(backoff.NewExponentialBackOff(), 5)) // transient dial/RPC failures","preventionTips":["Verify kops-controller endpoint and port in DNS before bootstrap","Open firewall/security-group paths for node->controller traffic","Keep client cert and ServerCA from the same cluster CA"],"tags":["grpc","network","tls","dial"],"backgroundTag":"connection-refused","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"}