go-kratos/kratos · error

kratos/nacos: ServiceInstance.Name can not be empty

Error message

kratos/nacos: ServiceInstance.Name can not be empty

What it means

ErrServiceInstanceNameEmpty (contrib/registry/nacos/registry.go:20) is returned by the nacos Registry when Register receives a *registry.ServiceInstance whose Name is empty. The instance Name becomes the nacos service name (GroupName/ServiceName) used in the RegisterInstance RPC, so an empty name cannot be registered and is rejected client-side before any nacos call.

Source

Thrown at contrib/registry/nacos/registry.go:20

import (
	"context"
	"errors"
	"fmt"
	"maps"
	"math"
	"net"
	"net/url"
	"strconv"

	"github.com/nacos-group/nacos-sdk-go/v2/clients/naming_client"
	"github.com/nacos-group/nacos-sdk-go/v2/common/constant"
	"github.com/nacos-group/nacos-sdk-go/v2/vo"

	"github.com/go-kratos/kratos/v3/registry"
)

var ErrServiceInstanceNameEmpty = errors.New("kratos/nacos: ServiceInstance.Name can not be empty")

const (
	defaultKind = "grpc"
	kindKey     = "kind"
	versionKey  = "version"
)

var (
	_ registry.Registrar = (*Registry)(nil)
	_ registry.Discovery = (*Registry)(nil)
)

type options struct {
	prefix  string
	weight  float64
	cluster string
	group   string
	kind    string

View on GitHub (pinned to 668db92c2c)

Solutions

1. Set ServiceInstance.Name to the nacos service name before Register, e.g. &registry.ServiceInstance{Name: "user.service", ...}
2. If the name comes from config, fail fast at startup when it is empty rather than passing it through
3. Add a startup assertion/validator over required instance fields (Name, Endpoints)

Example fix

// before
err := reg.Register(ctx, &registry.ServiceInstance{
    Endpoints: []string{"grpc://127.0.0.1:9000"},
}) // kratos/nacos: ServiceInstance.Name can not be empty

// after
err := reg.Register(ctx, &registry.ServiceInstance{
    Name:      "user.service",
    Version:   "v1.0.0",
    Endpoints: []string{"grpc://127.0.0.1:9000"},
})

func validInstance(svc *registry.ServiceInstance) error {
    if svc == nil || svc.Name == "" {
        return errors.New("service name required for nacos registration")
    }
    if len(svc.Endpoints) == 0 {
        return errors.New("at least one endpoint required")
    }
    return nil
}

When it happens

Trigger: reg.Register(ctx, &registry.ServiceInstance{Endpoints: [...], Metadata: [...]}) with Name unset (zero value ""); building the instance from a config field that is empty in this environment; passing a nil-ish or partially initialized struct during tests.

Common situations: Service name meant to come from an env var / config key that is missing in a new deployment; constructor refactoring that stopped populating Name; using the same registrar for multiple services and forgetting to set the name on one of them.

Related errors

• unable to parse repo url
• register failed: instance duplicated:
• Discovery.GetService fetch failed
• iterator closed
• watcher stopped

AI-assisted analysis of go-kratos/kratos@668db92c2c (2026-08-16). Data as JSON: /api/errors/986d904b67b64ab9. Report an issue: GitHub.