{"record":{"id":"9b62540116520e5c","repo":"kubernetes/kops","slug":"error-parsing-target-group-arn-v","errorCode":null,"errorMessage":"error parsing target group ARN: %v","messagePattern":"error parsing target group ARN: (.+?)","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"upup/pkg/fi/cloudup/awsup/aws_utils.go","lineNumber":254,"sourceCode":"// GetResourceName32 will attempt to calculate a meaningful name for a resource given a prefix\n// Will never return a string longer than 32 chars\nfunc GetResourceName32(cluster string, prefix string) string {\n\ts := prefix + \"-\" + strings.ReplaceAll(cluster, \".\", \"-\")\n\n\t// We always compute the hash and add it, lest we trick users into assuming that we never do this\n\topt := truncate.TruncateStringOptions{\n\t\tMaxLength:     32,\n\t\tAlwaysAddHash: true,\n\t\tHashLength:    6,\n\t}\n\treturn truncate.TruncateString(s, opt)\n}\n\n// NameForExternalTargetGroup will attempt to calculate a meaningful name for a target group given an ARN.\nfunc NameForExternalTargetGroup(targetGroupARN string) (string, error) {\n\tparsed, err := arn.Parse(targetGroupARN)\n\tif err != nil {\n\t\treturn \"\", fmt.Errorf(\"error parsing target group ARN: %v\", err)\n\t}\n\tresource := strings.Split(parsed.Resource, \"/\")\n\tif len(resource) != 3 || resource[0] != \"targetgroup\" {\n\t\treturn \"\", fmt.Errorf(\"error parsing target group ARN resource: %q\", parsed.Resource)\n\t}\n\treturn resource[1], nil\n}\n\nfunc IsIAMNoSuchEntityException(err error) bool {\n\tif err == nil {\n\t\treturn false\n\t}\n\tvar nse *iamtypes.NoSuchEntityException\n\treturn errors.As(err, &nse)\n}\n","sourceCodeStart":236,"sourceCodeEnd":270,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/upup/pkg/fi/cloudup/awsup/aws_utils.go#L236-L270","documentation":"NameForExternalTargetGroup derives a target group name from an ELBV2 target group ARN. It first calls arn.Parse on the supplied ARN; if the string is not a valid AWS ARN it returns this wrapped error. It is thrown only for malformed/unparseable ARN strings, before resource-part validation happens.","triggerScenarios":"Calling NameForExternalTargetGroup with an empty string, a target group name instead of a full ARN, a typo-truncated ARN, or any string not matching arn:partition:service:region:account-id:resource syntax.","commonSituations":"Users paste the target group name or URL from the AWS console instead of the ARN; config values read from env vars/cluster spec are empty or stale; copying an ARN from another partition or a legacy ELB (classic) whose ARN format differs.","solutions":["Verify the targetGroupARN string is a complete ARN of the form arn:aws:elasticloadbalancing:<region>:<account>:targetgroup/<name>/<id>.","Copy the ARN directly from `aws elbv2 describe-target-groups --query 'TargetGroups[*].TargetGroupArn'` instead of hand-typing it.","Check the cluster spec / config source feeding the ARN for empty or truncated values before calling the function."],"exampleFix":"// before\nname, err := NameForExternalTargetGroup(\"my-target-group\")\n// after\nname, err := NameForExternalTargetGroup(\"arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/my-target-group/abc123\")","handlingStrategy":"validation","validationCode":"if !strings.HasPrefix(arn, \"arn:\") { return fmt.Errorf(\"not an ARN: %q\", arn) }\nparsed, err := arn.Parse(arn); if err != nil { return err }","typeGuard":"func isTargetGroupARN(s string) bool {\n\tp, err := arn.Parse(s)\n\tif err != nil { return false }\n\tr := strings.Split(p.Resource, \"/\")\n\treturn len(r) == 3 && r[0] == \"targetgroup\"\n}","tryCatchPattern":"name, err := NameForExternalTargetGroup(tgARN)\nif err != nil {\n\treturn fmt.Errorf(\"invalid target group ARN %q: %w\", tgARN, err)\n}","preventionTips":["Store full ARNs copied from AWS CLI/console, never names or URLs","Validate ARNs at config-load time before passing to kOps tasks","Add a preflight isTargetGroupARN check in tooling that feeds ARNs programmatically"],"tags":["aws","elbv2","arn-parsing","config"],"backgroundTag":"invalid-arn-format","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"}