tsenart/vegeta · error

ErrNoMethod

ErrNoMethod

Error message

target: required method is missing

What it means

ErrNoMethod is returned by the JSONTargeter when a decoded Target has no HTTP method set. A vegeta target must specify the request method to build a valid http.Request.

Source

Thrown at lib/targets.go:96

			for i := range left {
				if left[i] != right[i] {
					return false
				}
			}
		}

		return true
	}
}

var (
	// ErrNoTargets is returned when not enough Targets are available.
	ErrNoTargets = errors.New("no targets to attack")
	// ErrNilTarget is returned when the passed Target pointer is nil.
	ErrNilTarget = errors.New("nil target")
	// ErrNoMethod is returned by JSONTargeter when a parsed Target has
	// no method.
	ErrNoMethod = errors.New("target: required method is missing")
	// ErrNoURL is returned by JSONTargeter when a parsed Target has no
	// URL.
	ErrNoURL = errors.New("target: required url is missing")
	// TargetFormats contains the canonical list of the valid target
	// format identifiers.
	TargetFormats = []string{HTTPTargetFormat, JSONTargetFormat}
)

const (
	// HTTPTargetFormat is the human readable identifier for the HTTP target format.
	HTTPTargetFormat = "http"
	// JSONTargetFormat is the human readable identifier for the JSON target format.
	JSONTargetFormat = "json"
)

// A Targeter decodes a Target or returns an error in case of failure.
// Implementations must be safe for concurrent use.
type Targeter func(*Target) error

View on GitHub (pinned to cf58112690)

Solutions

1. Add a "method" field to each JSON target: {"method":"GET","url":"http://host/"}.
2. Configure JSONTargeter with a non-empty default method so missing methods are filled in.
3. Validate target JSON against the expected schema before feeding it to vegeta.

Example fix

// before
{"url": "http://localhost:8080/"}
// after
{"method": "GET", "url": "http://localhost:8080/"}

var t vegeta.Target
if err := json.Unmarshal(raw, &t); err != nil { return err }
if t.Method == "" { return vegeta.ErrNoMethod }

if err := vegeta.ReadAllTargets(f, vegeta.JSONTargetFormat, &targets); err != nil {
    if errors.Is(err, vegeta.ErrNoMethod) {
        log.Fatal("each JSON target needs a \"method\" field")
    }
    return err
}

When it happens

Trigger: A JSON targets entry without a "method" field (and no default method configured on the JSONTargeter) passed to vegeta attack with -format=json.

Common situations: Hand-written JSON target files missing the method key, an empty method string after decoding, or JSONTargeter created without a default method while targets omit it.

Understand the failure class

Background: "Missing required field" and "field is required" errors: why libraries reject payloads that omit mandatory fields — this error's family across 20 libraries.

Related errors

• ErrNoURL
• ErrNoTargets
• rate frequency and time unit must be bigger than zero
• must specify at least resolver address
• lttb: min threshold is 3

AI-assisted analysis of tsenart/vegeta@cf58112690 (2026-08-31). Data as JSON: /api/errors/cc1e5acc9ba74c06. Report an issue: GitHub.