{"record":{"id":"ece9630898d7510d","repo":"kubernetes/kops","slug":"error-parsing-target-group-arn-resource-q","errorCode":null,"errorMessage":"error parsing target group ARN resource: %q","messagePattern":"error parsing target group ARN resource: %q","errorType":"exception","errorClass":null,"httpStatus":null,"severity":"error","filePath":"upup/pkg/fi/cloudup/awsup/aws_utils.go","lineNumber":258,"sourceCode":"\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":240,"sourceCodeEnd":270,"githubUrl":"https://github.com/kubernetes/kops/blob/4c8573c808a73d578c5eadc86d410646ea0b0d73/upup/pkg/fi/cloudup/awsup/aws_utils.go#L240-L270","documentation":"After the ARN parses successfully, NameForExternalTargetGroup splits the resource part on '/' and requires exactly three segments starting with 'targetgroup'. If the resource part has a different shape (or a different resource type), this error is returned. It indicates the ARN is valid but is not an ELBV2 target group ARN.","triggerScenarios":"Passing an ARN of a load balancer (resource 'loadbalancer/...'), a listener, a classic ELB, or a hand-edited targetgroup ARN where the '/<name>/<id>' suffix is missing or has extra slashes.","commonSituations":"Users supply a Network Load Balancer or Application Load Balancer ARN instead of a target group ARN in the cluster spec; ARNs truncated when pasting; automation that constructs ARNs by string concatenation drops the trailing ID segment.","solutions":["Confirm the ARN resource segment is 'targetgroup/<name>/<id>' with exactly three slash-separated parts.","Use `aws elbv2 describe-target-groups` to get the correct target group ARN rather than reusing a load balancer or listener ARN.","If constructing the ARN programmatically, include the target group's unique ID suffix."],"exampleFix":"// before\nNameForExternalTargetGroup(\"arn:aws:elasticloadbalancing:us-east-1:123456789012:loadbalancer/net/my-nlb/abc\")\n// after\nNameForExternalTargetGroup(\"arn:aws:elasticloadbalancing:us-east-1:123456789012:targetgroup/my-target-group/abc123\")","handlingStrategy":"validation","validationCode":"parsed, _ := arn.Parse(tgARN)\nparts := strings.Split(parsed.Resource, \"/\")\nif len(parts) != 3 || parts[0] != \"targetgroup\" { return fmt.Errorf(\"not a targetgroup ARN: %s\", parsed.Resource) }","typeGuard":"func isTargetGroupResource(resource string) bool {\n\tparts := strings.Split(resource, \"/\")\n\treturn len(parts) == 3 && parts[0] == \"targetgroup\"\n}","tryCatchPattern":"name, err := NameForExternalTargetGroup(tgARN)\nif err != nil {\n\treturn fmt.Errorf(\"ARN %q is not an ELBV2 target group: %w\", tgARN, err)\n}","preventionTips":["Do not reuse load balancer or listener ARNs where a target group ARN is required","Fetch ARNs via `aws elbv2 describe-target-groups` rather than string construction","Keep the full '<name>/<id>' suffix intact when copying ARNs"],"tags":["aws","elbv2","arn-parsing","validation"],"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"}