{"record":{"id":"603f26670483774b","repo":"kubernetes/kops","slug":"cannot-determine-challenge-endpoint-for-instance-i-603f26","errorCode":null,"errorMessage":"cannot determine challenge endpoint for instance id: %s","messagePattern":"cannot determine challenge endpoint for instance id: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"upup/pkg/fi/cloudup/linode/verifier.go","lineNumber":85,"sourceCode":"\t}\n\n\tinstanceIDString := strings.TrimPrefix(token, linodemetadata.LinodeAuthenticationTokenPrefix)\n\tinstanceID, err := strconv.Atoi(instanceIDString)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"invalid authorization token\")\n\t}\n\n\tinstance, err := v.client.GetInstance(ctx, instanceID)\n\tif err != nil {\n\t\treturn nil, fmt.Errorf(\"failed to get info for Akamai (Linode) instance %q: %w\", instanceIDString, err)\n\t}\n\tif instance == nil {\n\t\treturn nil, fmt.Errorf(\"failed to get info for Akamai (Linode) instance %q: empty response\", instanceIDString)\n\t}\n\n\taddresses, challengeEndpoints := gatherIPv4Addresses(instance.IPv4)\n\tif len(challengeEndpoints) == 0 {\n\t\treturn nil, fmt.Errorf(\"cannot determine challenge endpoint for instance id: %s\", instanceIDString)\n\t}\n\n\tresult := &bootstrap.VerifyResult{\n\t\tNodeName:          instance.Label,\n\t\tInstanceGroupName: instanceGroupNameFromTags(instance.Tags),\n\t\tCertificateNames:  addresses,\n\t\tChallengeEndpoint: challengeEndpoints[0],\n\t}\n\n\treturn result, nil\n}\n\n// gatherIPv4Addresses returns a list of IPv4 addresses and challenge endpoints from the given list of IPs.\nfunc gatherIPv4Addresses(ips []net.IP) ([]string, []string) {\n\taddresses := make([]string, 0, len(ips))\n\tchallengeEndpoints := make([]string, 0, len(ips))\n\n\tfor _, ip := range ips {","sourceCodeStart":67,"sourceCodeEnd":103,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/upup/pkg/fi/cloudup/linode/verifier.go#L67-L103","documentation":"Once instance data is fetched, VerifyToken derives the challenge endpoints from the instance's IPv4 addresses via gatherIPv4Addresses(instance.IPv4). To verify the node actually runs on the claimed Linode, it must challenge at least one routable IPv4 endpoint. If none exist (instance has no public or usable IPv4), verification cannot proceed and this error names the instance ID.","triggerScenarios":"gatherIPv4Addresses returns len(challengeEndpoints) == 0 — the Linode instance has no public IPv4 addresses (IPv4-only disabled / private-only networking), or IPv4 list is empty/nil in the API response. Exercised by TestLinodeVerifierVerifyTokenNoPrivateIP.","commonSituations":"Instances provisioned with only private/VLAN networking and no public IP; Linode configurations where public interface was removed; region/account configs with IPv4 allocation disabled; IPv6-only instances.","solutions":["Attach a public IPv4 address (or at least an address reachable by the verifier) to the Linode instance","If private-only networking is intentional, ensure the verifier can reach the instance's private IPv4 and that gatherIPv4Addresses includes private ranges for your setup","Re-check instance.Networking/IPv4 via the Linode API to confirm what addresses exist","Adjust kOps cluster config to require a public interface for verified instances"],"exampleFix":"// before (instance config)\ninterfaces: [{purpose: \"vlan\"}]\n// after (instance config)\ninterfaces: [{purpose: \"public\"}, {purpose: \"vlan\"}]","handlingStrategy":"validation","validationCode":"addrs, challenges := gatherIPv4Addresses(instance.IPv4)\nif len(challenges) == 0 {\n\treturn fmt.Errorf(\"instance %s has no challengeable IPv4; attach a public interface\", instance.Label)\n}","typeGuard":null,"tryCatchPattern":"result, err := verifier.VerifyToken(ctx, token, certs, challenge)\nif err != nil {\n\tif strings.Contains(err.Error(), \"cannot determine challenge endpoint\") {\n\t\treturn fmt.Errorf(\"ensure the Linode has a public IPv4 before bootstrapping: %w\", err)\n\t}\n\treturn err\n}","preventionTips":["Provision verified instances with at least one public IPv4 interface","Audit cluster specs that disable public interfaces","Check instance.Networking via the Linode API before bootstrapping","Keep private-only instances reachable from the verifier if that topology is required"],"tags":["linode","networking","ipv4","challenge"],"backgroundTag":"no-routable-challenge-endpoint","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"}