Configuration

Weaver uses Viper for configuration management and supports multiple formats:

• YAML
• TOML
• JSON
• Environment variables

Injecting Component Configuration

Use the weaver.WithConfig[T] generic type together with a struct tag to inject configuration into components. The tags conf, config and weaver are all supported; conf is recommended:

type options struct {
    Host string
    Port int
    Auth struct {
        Username string
        Password string
    }
}

type service struct {
    weaver.Implements[Service]
    weaver.WithConfig[options] `conf:"service"` // loaded from the "service" key
}

// Access the config
func (s *service) Init(ctx context.Context) error {
    cfg := s.Config()
    s.Logger(ctx).Info("Service config", "host", cfg.Host, "port", cfg.Port)
    return nil
}

The matching config file:

service:
  host: 0.0.0.0
  port: 8080
  auth:
    username: admin
    password: secret

System Configuration

The weaver key is reserved for framework settings, currently logging:

weaver:
  logger:
    level: info
    type: json
    addsource: true

See Logging.

Hot Reload

Weaver watches the config file via Viper's WatchConfig:

• When the file changes, the configuration of all registered components is reloaded automatically (UnmarshalKey is re-run).
• The framework then shuts down all components (Shutdown) and starts them again (Start), so new config takes effect without restarting the process.

This means saving an updated weaver.yaml is enough — no process restart required (as long as the config file was passed via -conf).

Specifying the Config File

Pass it via flag or environment variable:

go run main.go -conf weaver.yaml
# or
SERVICE_CONFIG=weaver.yaml go run main.go

When no config file is specified, WithConfig injects nothing.