stocklet/internal/pkg/config/config.go

// Copyright (C) 2024 Declan Teevan
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package config

import (
	"os"

	"github.com/hexolan/stocklet/internal/pkg/errors"
)

// Load an option from an environment variable
func loadFromEnv(name string) *string {
	value, exists := os.LookupEnv(name)
	if !exists || value == "" {
		return nil
	}

	return &value
}

// Require an option from an environment variable
func RequireFromEnv(name string) (string, error) {
	value := loadFromEnv(name)
	if value == nil {
		return "", errors.NewServiceErrorf(errors.ErrCodeService, "failed to load required cfg option (%s)", name)
	}

	return *value, nil
}

// Shared configuration implemented by all services
type SharedConfig struct {
	// Env Var: "MODE" (optional)
	// 'dev' or 'development' -> true
	// Defaults to false
	DevMode bool

	Otel OtelConfig
}

// Load the options in the shared config
func (cfg *SharedConfig) Load() error {
	// Determine application mode
	cfg.DevMode = false
	if mode, err := RequireFromEnv("MODE"); err == nil && (mode == "dev" || mode == "development") {
		cfg.DevMode = true
	}

	// load the Open Telemetry config
	cfg.Otel = OtelConfig{}
	if err := cfg.Otel.Load(); err != nil {
		return err
	}

	// Config successfully loaded
	return nil
}