guesstimate/server/internal/config/config.go

package config

import (
	"io"
	"io/ioutil"

	"github.com/caarlos0/env/v6"
	"github.com/pkg/errors"

	"gopkg.in/yaml.v2"
)

// Config is the configuration struct
type Config struct {
	HTTP   HTTPConfig   `yaml:"http"`
	Client ClientConfig `yaml:"client"`
	Data   DataConfig   `ymal:"data"`
}

// HTTPConfig is the configuration part which defines HTTP related params
type HTTPConfig struct {
	Address   string `yaml:"address" env:"GUESSTIMATE_HTTP_ADDRESS"`
	PublicDir string `yaml:"publicDir" env:"GUESSTIMATE_PUBLIC_DIR"`
}

// ClientConfig is the configuration part which defines the client app related params
type ClientConfig struct {
	PublicBaseURL string `yaml:"publicbaseurl" env:"GUESSTIMATE_CLIENT_PUBLIC_BASE_URL"`
}

// DataConfig is the configuration part which defines data related params
type DataConfig struct {
	Path string `yaml:"path" env:"GUESSTIMATE_DATA_PATH"`
}

// NewFromFile retrieves the configuration from the given file
func NewFromFile(filepath string) (*Config, error) {
	config := NewDefault()

	data, err := ioutil.ReadFile(filepath)
	if err != nil {
		return nil, errors.Wrapf(err, "could not read file '%s'", filepath)
	}

	if err := yaml.Unmarshal(data, config); err != nil {
		return nil, errors.Wrapf(err, "could not unmarshal configuration")
	}

	return config, nil
}

// WithEnvironment retrieves the configuration from env vars
func WithEnvironment(conf *Config) error {
	if err := env.Parse(conf); err != nil {
		return err
	}

	return nil
}

// NewDumpDefault retrieves the default configuration
func NewDumpDefault() *Config {
	config := NewDefault()
	return config
}

// NewDefault creates and returns a new default configuration
func NewDefault() *Config {
	return &Config{
		HTTP: HTTPConfig{
			Address:   ":8081",
			PublicDir: "public",
		},
		Client: ClientConfig{
			PublicBaseURL: "http://localhost:8080",
		},
		Data: DataConfig{
			Path: "guesstimate.db",
		},
	}
}

// Dump writes a given config to a config file
func Dump(config *Config, w io.Writer) error {
	data, err := yaml.Marshal(config)
	if err != nil {
		return errors.Wrap(err, "could not dump config")
	}

	if _, err := w.Write(data); err != nil {
		return err
	}

	return nil
}