{"record":{"id":"fcfea920d64b2c64","repo":"kubernetes/kops","slug":"cannot-determine-challenge-endpoint-for-server-d","errorCode":null,"errorMessage":"cannot determine challenge endpoint for server %d","messagePattern":"cannot determine challenge endpoint for server (.+?)","errorType":"error_code","errorClass":null,"httpStatus":null,"severity":"error","filePath":"upup/pkg/fi/cloudup/do/verifier.go","lineNumber":107,"sourceCode":"\t\t}\n\t}\n\n\t// Note: we use TLS passthrough, so we lose the client IP address.\n\t// We therefore don't have a great way to verify the request.\n\t// We do at least prevent duplicate node registrations, preventing some attacks here.\n\n\t// The node challenge is important here though, verifying the caller has control of the IP address.\n\n\tnodeName := \"\"\n\tif len(addresses) == 0 {\n\t\t// Name seems a better default than the first IP, but we have to match what other components are expecting\n\t\tnodeName = droplet.Name\n\t} else {\n\t\tnodeName = addresses[0]\n\t}\n\n\tif len(challengeEndpoints) == 0 {\n\t\treturn nil, fmt.Errorf(\"cannot determine challenge endpoint for server %d\", serverID)\n\t}\n\n\tresult := &bootstrap.VerifyResult{\n\t\tNodeName:          nodeName,\n\t\tCertificateNames:  addresses,\n\t\tChallengeEndpoint: challengeEndpoints[0],\n\t}\n\n\tfor _, tag := range droplet.Tags {\n\t\tif strings.HasPrefix(tag, TagKubernetesInstanceGroup+\":\") {\n\t\t\tresult.InstanceGroupName = strings.TrimPrefix(tag, TagKubernetesInstanceGroup+\":\")\n\t\t}\n\t}\n\treturn result, nil\n}\n","sourceCodeStart":89,"sourceCodeEnd":123,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/upup/pkg/fi/cloudup/do/verifier.go#L89-L123","documentation":"Post-collection guard in the DO verifier: no challenge endpoints could be derived from the droplet's addresses, so the node-identity challenge (proving control of the IP) cannot be issued. TLS passthrough means the challenge is the primary verification mechanism here, hence the hard failure.","triggerScenarios":"Thrown at upup/pkg/fi/cloudup/do/verifier.go:107 when the library encounters an invalid state.","commonSituations":"See trigger scenarios.","solutions":["Verify the droplet has private network addresses attached","Ensure the node's challenge server is running and reachable","Re-run the bootstrap registration"],"exampleFix":null,"handlingStrategy":"validation","validationCode":null,"typeGuard":null,"tryCatchPattern":null,"preventionTips":[],"tags":[],"backgroundTag":null,"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"}