A Simple Go Configuration

I use this same configuration structure and supporting functions in most every Go program I work on. It is pretty simple but makes it easy to keep global variables orgranized and configurable.

Here is what I do:

1. Create a type config struct

2. Every configurable variable for the program becomes a Member field of the Configuration structure.

3. Register every field of the Configuration Structure with go’s builtin flags package such that the flags are parsed when the program starts we can use our configuration variable.

import (
    "flags"
)

typedef Configuration struct {
    Broker string           `json:"broker"`
}

var (
    config Configuration
)

func init() {
    flags.StringVar(&config.Broker, "broker", "localhost", "Set the MQTT Broker")
}

func main() {
    flags.Parse()
    
    mqtt_init(config.Broker)
}

func (c *Configuration) Save(fname string) error {
    // encode configuration into a JSON struct

    // save json string to file
}

func (c *Configuration) Read(fname string) error {
    // Read json string from file

    // decode configuration from the JSON struct.
}

Adding the Save() and Read() functions now allow us to read and write our configuration to and from a file.