{"record":{"id":"13a39cef5b221b08","repo":"kubernetes/kops","slug":"error-from-callback-challenge-w","errorCode":null,"errorMessage":"error from callback challenge: %w","messagePattern":"error from callback challenge: %w","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"pkg/bootstrap/challenge_client.go","lineNumber":122,"sourceCode":"\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":104,"sourceCodeEnd":130,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/pkg/bootstrap/challenge_client.go#L104-L130","documentation":"The gRPC call to the callback server's Challenge RPC returned an error; it is wrapped with this message. This is a server-side or RPC-level failure (unauthenticated TLS client, missing required subject, server rejecting the request, deadline exceeded), not a local validation problem.","triggerScenarios":"Calling DoCallbackChallenge when the server rejects the Challenge RPC: mTLS client cert not accepted, node not registered, context deadline exceeded, or the server returns a gRPC status error.","commonSituations":"Client certificate subject not matching the required kops-controller subject; server-side authorization denying the node; network interruption mid-RPC; server logs containing the matching underlying error.","solutions":["Check kops-controller logs for the corresponding Challenge RPC error","Verify the client certificate subject matches challengeKopsControllerSubject for the cluster","Retry with a longer context deadline if it was a timeout","Re-issue the client certificate from the cluster CA if the subject/CA is wrong"],"exampleFix":"null","handlingStrategy":"retry","validationCode":"// ensure client cert subject matches expected controller subject\nif clientCert.Subject.CommonName != expectedSubject {\n\treturn fmt.Errorf(\"client cert subject %q != required %q\", clientCert.Subject.CommonName, expectedSubject)\n}","typeGuard":null,"tryCatchPattern":"if err := client.DoCallbackChallenge(ctx, clusterName, ch); err != nil {\n\tvar st status.Status\n\tif errors.As(err, &st) && st.Code() == codes.DeadlineExceeded {\n\t\t// retry with longer deadline\n\t}\n\treturn fmt.Errorf(\"challenge RPC failed: %w\", err)\n}","preventionTips":["Issue client certs with the exact required subject for the cluster","Set generous context deadlines for the challenge RPC","Correlate with kops-controller server logs when it fails"],"tags":["grpc","rpc","mtls","challenge"],"backgroundTag":"grpc-call-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"}