clipper/backend/config/config.go

package config

import (
	"errors"
	"fmt"
	"os"
)

type Environment int

const (
	EnvDevelopment Environment = iota
	EnvProduction
)

type Config struct {
	Environment        Environment
	BindAddr           string
	TLSCertFile        string
	TLSKeyFile         string
	DatabaseURL        string
	AWSAccessKeyID     string
	AWSSecretAccessKey string
	AWSRegion          string
	S3Bucket           string
	AssetsHTTPBasePath string
}

func NewFromEnv() (Config, error) {
	envString := os.Getenv("ENV")
	var env Environment
	switch envString {
	case "production":
		env = EnvProduction
	case "development":
		env = EnvDevelopment
	case "":
		return Config{}, errors.New("ENV not set")
	default:
		return Config{}, fmt.Errorf("invalid ENV value: %s", envString)
	}

	bindAddr := os.Getenv("BIND_ADDR")
	if bindAddr == "" {
		bindAddr = "localhost:8888"
	}

	tlsCertFile := os.Getenv("TLS_CERT_FILE")
	tlsKeyFile := os.Getenv("TLS_KEY_FILE")
	if (tlsCertFile == "" && tlsKeyFile != "") || (tlsCertFile != "" && tlsKeyFile == "") {
		return Config{}, errors.New("Both TLS_CERT_FILE and TLS_KEY_FILE must be set")
	}

	databaseURL := os.Getenv("DATABASE_URL")
	if databaseURL == "" {
		return Config{}, errors.New("DATABASE_URL not set")
	}

	awsAccessKeyID := os.Getenv("AWS_ACCESS_KEY_ID")
	if awsAccessKeyID == "" {
		return Config{}, errors.New("AWS_ACCESS_KEY_ID not set")
	}

	awsSecretAccessKey := os.Getenv("AWS_SECRET_ACCESS_KEY")
	if awsSecretAccessKey == "" {
		return Config{}, errors.New("AWS_SECRET_ACCESS_KEY not set")
	}

	awsRegion := os.Getenv("AWS_REGION")
	if awsRegion == "" {
		return Config{}, errors.New("AWS_REGION not set")
	}

	s3Bucket := os.Getenv("S3_BUCKET")
	if s3Bucket == "" {
		return Config{}, errors.New("S3_BUCKET not set")
	}

	assetsHTTPBasePath := os.Getenv("ASSETS_HTTP_BASE_PATH")

	return Config{
		Environment:        env,
		BindAddr:           bindAddr,
		TLSCertFile:        tlsCertFile,
		TLSKeyFile:         tlsKeyFile,
		DatabaseURL:        databaseURL,
		AWSAccessKeyID:     awsAccessKeyID,
		AWSSecretAccessKey: awsSecretAccessKey,
		AWSRegion:          awsRegion,
		S3Bucket:           s3Bucket,
		AssetsHTTPBasePath: assetsHTTPBasePath,
	}, nil
}