func (v *Viper) findConfigFile() (string, error) {
	finder := finder{
		paths:            v.configPaths,
		fileNames:        []string{v.configName},
		extensions:       SupportedExts,
		withoutExtension: v.configType != "",
	}
	file, err := finder.Find(afero.NewIOFS(v.fs))
	if err != nil {
		return "", err
	}
	if file == "" {
		return "", ConfigFileNotFoundError{v.configName, fmt.Sprintf("%s", v.configPaths)}
	}
	return file, nil
}
Search all configPaths for any config file.
Returns the first path that exists (and is a config file).
package viper
import (
	"fmt"
	"github.com/spf13/afero"
)