Configuration

Contents

1. Configuration
2. Running from Default values
3. Running from Flags
4. Running from Environment variables
5. Running from config file
6. Manually adding Viper

Configuration

Generated atlas projects use viper, a complete configuration solution that allows an application to run from different environments. Viper also provides precedence order which is in the order as below.

Running from Default Values

By default if you don't change anything your application will run with the values in config.go

Running from Flags

go run cmd/server/*.go --database.port 5432

Running from Environment Variables

export DATABASE_PORT=5432
go run cmd/server/*.go

Running from Config file

Change the configuration for defaultConfigDirectory and defaultConfigFile to point to your configuration file. You can either change it in config.go, passing it as environment variables, or flags.

go run cmd/server/*.go --config.source "some/path/" --config.file "config_file.yaml" 

Manually adding Viper

1. Copy config.go and add it to your project under cmd/server/config.go
2. Update config.go by setting all your default values
3. Import following packages inside main.go:

import (
	"github.com/spf13/pflag"
	"github.com/spf13/viper"
)

4. Add the following snippet of code inside your main.go to initialize all the viper configuration.

func init() {
	pflag.Parse()
	viper.BindPFlags(pflag.CommandLine)
	viper.AutomaticEnv()
	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	viper.AddConfigPath(viper.GetString("config.source"))
	if viper.GetString("config.file") != "" {
		log.Printf("Serving from configuration file: %s", viper.GetString("config.file"))
		viper.SetConfigName(viper.GetString("config.file"))
		if err := viper.ReadInConfig(); err != nil {
			log.Fatalf("cannot load configuration: %v", err)
		}
	} else {
		log.Printf("Serving from default values, environment variables, and/or flags")
	}
	resource.RegisterApplication(viper.GetString("app.id"))
	resource.SetPlural()
}

5. To get or set viper configuration inside your code use the following methods:

// Retrieving a string
viper.GetString("database.address")
// Retrieving a bool 
viper.GetBool("database.enable")