hyperledger/fabric · error

too few arguments

Error message

too few arguments

What it means

In Hyperledger Fabric's statecouchdb package, GetDatabaseSecurity() fetches a database's _security document from CouchDB and decodes it into a databaseSecurity struct. If the raw HTTP response body is not valid JSON or does not match the expected struct (e.g. non-string members where []string are expected), json.Unmarshal fails and the error is wrapped as 'error unmarshalling json data'. This aborts the security-read operation.

Source

Thrown at ccaas_builder/cmd/detect/main.go:39

func main() {
	logger.Println("::Detect")

	if err := run(); err != nil {
		logger.Printf("::Error: %v\n", err)
		os.Exit(1)
	}

	logger.Printf("::Type detected as ccaas")
}

type chaincodeMetadata struct {
	Type string `json:"type"`
}

func run() error {
	if len(os.Args) < 3 {
		return errors.New("too few arguments")
	}

	chaincodeMetaData := os.Args[2]

	// Check metadata file's existence
	metadataFile := filepath.Join(chaincodeMetaData, "metadata.json")
	if _, err := os.Stat(metadataFile); err != nil {
		return errors.WithMessagef(err, "%s not found ", metadataFile)
	}

	// Read the metadata file
	mdbytes, err := os.ReadFile(metadataFile)
	if err != nil {
		return errors.WithMessagef(err, "%s not readable", metadataFile)
	}

	var metadata chaincodeMetadata
	err = json.Unmarshal(mdbytes, &metadata)

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Verify CouchDB is reachable directly and the URL/credentials are correct so it returns real JSON, not a proxy error page
2. curl the _security endpoint (GET http://<couchdb>:5984/<db>/_security) and confirm the body is valid JSON matching {admins:{names:[],roles:[]},members:{...}}
3. Check for a proxy/middleware rewriting the response; bypass it for the CouchDB host
4. Check Fabric and CouchDB version compatibility
5. Enable debug logging (couchdbLogger) to inspect the raw response

Example fix

// before
resp, err := http.Get("http://proxy:80/couchdb/db/_security") // proxy returns HTML
json.Unmarshal(raw, jsonResponse) // fails
// after
client := &http.Client{} // point directly at CouchDB, or check Content-Type first
resp, err := client.Get("http://couchdb:5984/db/_security")
if ct := resp.Header.Get("Content-Type"); !strings.HasPrefix(ct, "application/json") {
    return nil, errors.New("non-JSON response from CouchDB")
}

raw, _ := io.ReadAll(resp.Body)
if !json.Valid(raw) {
    return fmt.Errorf("non-JSON _security response: %.200s", raw)
}

func isJSON(b []byte) bool {
    var v any
    return json.Unmarshal(b, &v) == nil
}

sec, err := db.GetDatabaseSecurity()
if err != nil {
    if strings.Contains(err.Error(), "error unmarshalling json data") {
        // log raw response, check CouchDB reachability/auth, retry
        return fmt.Errorf("couchdb returned non-JSON security doc: %w", err)
    }
    return err
}

When it happens

Trigger: Calling GetDatabaseSecurity() when the CouchDB server returns a body that is not valid JSON (e.g. an HTML error page from a proxy, or a malformed/truncated _security response), or JSON whose shape does not fit databaseSecurity (admins/members names/roles fields of unexpected types).

Common situations: A reverse proxy or load balancer intercepting CouchDB traffic and returning HTML; CouchDB returning an error body for an unauthorized request that the client still tries to decode; corrupted or non-JSON response due to network interruption.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

Related errors

• Failed opening file %s: %v
• config isn't valid
• incorrect number of arguments
• connection.json not found in source folder: %s
• failed to marshal config

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/26b0bbdb81bbff45. Report an issue: GitHub.