grpc/grpc-go · error

grpctransport: ServerURI is not set in ServerIdentifier

Error message

grpctransport: ServerURI is not set in ServerIdentifier

What it means

grpctransport.Builder.Build (grpc_transport.go:90-91) requires that ServerIdentifier.ServerURI is a non-empty string — it is the target the gRPC channel dials. An empty URI means there is no server to connect to, so Build fails immediately before any connection attempt.

Source

Thrown at internal/xds/clients/grpctransport/grpc_transport.go:91

}

// NewBuilder provides a builder for creating gRPC-based Transports using
// the credentials from provided map of credentials names to
// credentials.Bundle.
func NewBuilder(configs map[string]Config) *Builder {
	return &Builder{
		configs:     configs,
		connections: make(map[clients.ServerIdentifier]*grpc.ClientConn),
		refs:        make(map[clients.ServerIdentifier]int),
	}
}

// Build returns a gRPC-based clients.Transport.
//
// The Extension field of the ServerIdentifier must be a ServerIdentifierExtension.
func (b *Builder) Build(si clients.ServerIdentifier) (clients.Transport, error) {
	if si.ServerURI == "" {
		return nil, fmt.Errorf("grpctransport: ServerURI is not set in ServerIdentifier")
	}
	if si.Extensions == nil {
		return nil, fmt.Errorf("grpctransport: Extensions is not set in ServerIdentifier")
	}
	sce, ok := si.Extensions.(ServerIdentifierExtension)
	if !ok {
		return nil, fmt.Errorf("grpctransport: Extensions field is %T, but must be %T in ServerIdentifier", si.Extensions, ServerIdentifierExtension{})
	}

	config, ok := b.configs[sce.ConfigName]
	if !ok {
		return nil, fmt.Errorf("grpctransport: unknown config name %q specified in ServerIdentifierExtension", sce.ConfigName)
	}
	if config.Credentials == nil {
		return nil, fmt.Errorf("grpctransport: config %q has nil credentials bundle", sce.ConfigName)
	}

	b.mu.Lock()

View on GitHub (pinned to 03255a9237)

Solutions

1. Set ServerIdentifier.ServerURI to the xDS/LRS server address (e.g. dns:///xds-server:443) before calling Build.
2. Validate that the config source providing the URI is populated.
3. Add a precondition check in your code that ServerURI is non-empty before invoking Build.

Example fix

// before:
//   si := clients.ServerIdentifier{}
//   tr, err := builder.Build(si)
// after:
//   si := clients.ServerIdentifier{ServerURI: "dns:///xds-server:443"}
//   tr, err := builder.Build(si)

func validateServerIdentifier(si clients.ServerIdentifier) error {
    if si.ServerURI == "" {
        return errors.New("ServerIdentifier.ServerURI must be set")
    }
    return nil
}

When it happens

Trigger: Calling builder.Build(si) where si.ServerURI is empty — the ServerIdentifier was constructed without setting ServerURI, or a templating/config step left it blank.

Common situations: The ServerIdentifier was populated from a config map whose server_uri key was missing; the URI was read from an env var that was unset; a struct literal omitted the field by mistake.

Related errors

• grpctransport: Extensions is not set in ServerIdentifier
• xds: required field `xds_servers` not found in bootstrap con
• jwt_token_file is required in JWT call credentials config
• grpctransport: unknown config name %q specified in ServerIde
• grpctransport: config %q has nil credentials bundle

AI-assisted analysis of grpc/grpc-go@03255a9237 (2026-08-07). Data as JSON: /api/errors/34249a342e6a46fc. Report an issue: GitHub.