Function NewConfigFromToml

config.go:281–422

NewConfigFromToml creates a Config from a reader reading from a TOML configuration. comp describes all the existing components.

(f io.Reader, comp Components)

// NewConfigFromToml creates a Config from a reader reading from a TOML
// configuration. comp describes all the existing components.
func NewConfigFromToml(f io.Reader, comp Components) (*Config, error) {
	f, err := replaceEnvVars(f, os.Getenv)
	if err != nil {
		return nil, fmt.Errorf("can't replace config with env vars: %v", err)
	}

	// Parse che configuration. Part of the configuration will be
	// captured as toml.Primitive for deferred parsing (see comment
	// at top of the file)
	cfg := Config{}
	md, err := toml.DecodeReader(f, &cfg)
	if err != nil {
		return nil, fmt.Errorf("error parsing topology: %v", err)
	}

	// We now go through inputs, filters and outputs, and match the names
	// to the actual object descriptions provided by each respective package.
	// Through the description, we also acquire an instance to the actual
	// custom configuration structure, that will be filled later.
	for _, inp := range comp.Inputs {
		if strings.EqualFold(inp.Name, cfg.Input.Name) {
			cfg.Input.desc = &inp
			break
		}
	}
	if cfg.Input.desc == nil {
		return nil, fmt.Errorf("input does not exist: %q", cfg.Input.Name)
	}

	for idx := range cfg.Filter {
		cfgfil := &cfg.Filter[idx]
		for _, fil := range comp.Filters {
			if strings.EqualFold(fil.Name, cfgfil.Name) {
				cfgfil.desc = &fil
				break
			}
		}
		if cfgfil.desc == nil {
			return nil, fmt.Errorf("filter does not exist: %q", cfgfil.Name)
		}
	}

	for _, out := range comp.Outputs {
		if strings.EqualFold(out.Name, cfg.Output.Name) {
			cfg.Output.desc = &out
			break
		}
	}
	if cfg.Output.desc == nil {
		return nil, fmt.Errorf("output does not exist: %q", cfg.Output.Name)
	}

	// Upload can be empty
	for _, upl := range comp.Uploads {
		if strings.EqualFold(upl.Name, cfg.Upload.Name) {
			cfg.Upload.desc = &upl
			break
		}