webhooker/internal/config/config.go

// Package config loads application configuration from environment variables.
package config

import (
	"errors"
	"fmt"
	"log/slog"
	"os"
	"strconv"
	"strings"

	"go.uber.org/fx"
	"sneak.berlin/go/webhooker/internal/globals"
	"sneak.berlin/go/webhooker/internal/logger"

	// Populates the environment from a ./.env file automatically for
	// development configuration. Kept in one place only (here).
	_ "github.com/joho/godotenv/autoload"
)

const (
	// EnvironmentDev represents development environment.
	EnvironmentDev = "dev"
	// EnvironmentProd represents production environment.
	EnvironmentProd = "prod"

	// defaultPort is the default HTTP listen port.
	defaultPort = 8080
)

// ErrInvalidEnvironment is returned when WEBHOOKER_ENVIRONMENT
// contains an unrecognised value.
var ErrInvalidEnvironment = errors.New("invalid environment")

//nolint:revive // ConfigParams is a standard fx naming convention.
type ConfigParams struct {
	fx.In

	Globals *globals.Globals
	Logger  *logger.Logger
}

// Config holds all application configuration loaded from
// environment variables.
type Config struct {
	DataDir         string
	Debug           bool
	MaintenanceMode bool
	Environment     string
	MetricsPassword string
	MetricsUsername string
	Port            int
	SentryDSN       string
	params          *ConfigParams
	log             *slog.Logger
}

// IsDev returns true if running in development environment.
func (c *Config) IsDev() bool {
	return c.Environment == EnvironmentDev
}

// IsProd returns true if running in production environment.
func (c *Config) IsProd() bool {
	return c.Environment == EnvironmentProd
}

// envString returns the value of the named environment variable,
// or an empty string if not set.
func envString(key string) string {
	return os.Getenv(key)
}

// envBool returns the value of the named environment variable
// parsed as a boolean. Returns defaultValue if not set.
func envBool(key string, defaultValue bool) bool {
	if v := os.Getenv(key); v != "" {
		return strings.EqualFold(v, "true") || v == "1"
	}

	return defaultValue
}

// envInt returns the value of the named environment variable
// parsed as an integer. Returns defaultValue if not set or
// unparseable.
func envInt(key string, defaultValue int) int {
	if v := os.Getenv(key); v != "" {
		i, err := strconv.Atoi(v)
		if err == nil {
			return i
		}
	}

	return defaultValue
}

// New creates a Config by reading environment variables.
//
//nolint:revive // lc parameter is required by fx even if unused.
func New(lc fx.Lifecycle, params ConfigParams) (*Config, error) {
	log := params.Logger.Get()

	// Determine environment from WEBHOOKER_ENVIRONMENT env var,
	// default to dev
	environment := os.Getenv("WEBHOOKER_ENVIRONMENT")
	if environment == "" {
		environment = EnvironmentDev
	}

	// Validate environment
	if environment != EnvironmentDev &&
		environment != EnvironmentProd {
		return nil, fmt.Errorf(
			"%w: WEBHOOKER_ENVIRONMENT must be '%s' or '%s', got '%s'",
			ErrInvalidEnvironment,
			EnvironmentDev, EnvironmentProd, environment,
		)
	}

	// Load configuration values from environment variables
	s := &Config{
		DataDir:         envString("DATA_DIR"),
		Debug:           envBool("DEBUG", false),
		MaintenanceMode: envBool("MAINTENANCE_MODE", false),
		Environment:     environment,
		MetricsUsername: envString("METRICS_USERNAME"),
		MetricsPassword: envString("METRICS_PASSWORD"),
		Port:            envInt("PORT", defaultPort),
		SentryDSN:       envString("SENTRY_DSN"),
		log:             log,
		params:          &params,
	}

	// Set default DataDir. All SQLite databases (main application
	// DB and per-webhook event DBs) live here. The same default is
	// used regardless of environment; override with DATA_DIR if
	// needed.
	if s.DataDir == "" {
		s.DataDir = "/var/lib/webhooker"
	}

	if s.Debug {
		params.Logger.EnableDebugLogging()
	}

	// Log configuration summary (without secrets)
	log.Info("Configuration loaded",
		"environment", s.Environment,
		"port", s.Port,
		"debug", s.Debug,
		"maintenanceMode", s.MaintenanceMode,
		"dataDir", s.DataDir,
		"hasSentryDSN", s.SentryDSN != "",
		"hasMetricsAuth",
		s.MetricsUsername != "" && s.MetricsPassword != "",
	)

	return s, nil
}