Go generate configuration

A convenient configuration generator based on an yaml template with env support and the possibility of a hot reload

Install

GOPATH=./bin go install github.com/evald24/go-gen-config/cmd/go-gen-config

Usage:

At the beginning, create a file with a configuration template (e.g. config.template.yaml)

Then execute the generation command:

./bin/go-gen-config -t ./example/config.template.yaml -o ./example/config/config.gen.go -c ./example/config.yaml

Args	Description
-t	required The path to the yaml template file
-o	required The path where the code will be generated
-c	optional The path where the configuration file will be generated. If the file already exists, it only adds new default values.

Schema

Template

appName: # The name will be converted to CamelCase
  description: Application Name # Its description
  type: string # The type in which the parameter is specified
  env: APP_NAME # A unique value that is set from the environment
  value: Hello World # The value in the specified data type

logLevel:
  type: enum
  env: LOG_LEVEL
  value: DEBUG
  enum:
    - DEBUG
    - INFO
    - WARNING
    - ERROR

project:
  type: struct
  description: Project information
  value:
    name:
      type: string
      value: example-service-api
      description: Name of the project
    title:
      type: string
      value: Example of a service API
      description: Title of the project
    description:
      type: string
      value: Description for an example of a service API
      description: Description of the project
    environment:
      type: enum
      value: DEV
      env: PROJECT_ENV
      enum: [DEV, STG, PROD]
      description: Project environment

Outputs

Generated configuration file

If the -c argument was specified

appName: Hello World
logLevel: DEBUG
project:
  description: Description for an example of a service API
  environment: DEV
  name: example-service-api
  title: Example of a service API

Code generated

// Code generated by "go-gen-config"; DO NOT EDIT.

package config

...

// Conifg - Basic structure with configuration
type Config struct {
	// Debug - Debug mode
	Debug bool `yaml:"debug" env:"DEBUG" default:"true"`
	// LogLevel - Description of the variable
	LogLevel EnumLogLevel `yaml:"logLevel" env:"LOG_LEVEL" default:"DEBUG"`
	// Project - Project information
	Project StructProject `yaml:"project"`
}

// EnumLogLevel - Description of the variable
type EnumLogLevel = string

const (
	// LogLevelDebug - Description of the variable
	LogLevelDebug EnumLogLevel = "DEBUG"
	// LogLevelInfo - Description of the variable
	LogLevelInfo = "INFO"
	// LogLevelWarning - Description of the variable
	LogLevelWarning = "WARNING"
	// LogLevelError - Description of the variable
	LogLevelError = "ERROR"
)

// StructProject - Project information
type StructProject struct {
	// Description - Description of the project
	Description string `yaml:"description" default:"Description for an example of a service API"`
	// Name - Name of the project
	Name string `yaml:"name" default:"example-service-api"`
	// Title - Title of the project
	Title string `yaml:"title" default:"Example of a service API"`
	// Environment - Project environment
	Environment EnumProjectEnvironment `yaml:"environment" env:"PROJECT_ENV" default:"DEV"`
}

// EnumProjectEnvironment - Project environment
type EnumProjectEnvironment = string

const (
	// ProjectEnvironmentDev - Project environment
	ProjectEnvironmentDev EnumProjectEnvironment = "DEV"
	// ProjectEnvironmentStg - Project environment
	ProjectEnvironmentStg = "STG"
	// ProjectEnvironmentProd - Project environment
	ProjectEnvironmentProd = "PROD"
)

// GetConfig - get the configuration
func GetConfig() *Config {
	return cfg
}

var fileConfig string
var cfg *Config

// Init - initializing the configuration
func Init(configPath string) (*Config, error) {
	...
}

// UpdateConfig - Updates the configuration by rereading
func UpdateConfig() error {
	...
}

Usage Example

package main

import (
	"fmt"
	"log"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/evald24/go-gen-config/example/config" // The path to the package in your project
)

func main() {
	cfg, err := config.Init("example/config.yaml");
	if err != nil {
		log.Fatal(err)
	}

	go hotReloadConfig()

	fmt.Printf("config: %+v\n", cfg)
	fmt.Printf("project name: %s", cfg.Project.Name)
}

// Example of a hot reload configuration
func hotReloadConfig() {
	signalHotReload := make(chan os.Signal, 1)
	signal.Notify(signalHotReload, syscall.SIGHUP)

	for {
		<-signalHotReload
		if err := config.UpdateConfig(); err != nil {
			log.Fatal(err)
		}
		fmt.Printf("hot reloaded config: %+v\n", time.Now())
	}
}

If you need to update the configuration on the fly, you can send a `SIGHUP' signal to the process.

kill -SIGHUP [PID]

The configuration file and the environment will be read again

Types

You can see the full example of the template here: example/config.template.yaml

Attribute	Description
type	required The type in which the parameter is specified
value	optional Default value
env	optional The value in the specified data type
description	optional Description, will be converted to a comment in the code
enum	optional Array of enumerations

Support types

Attribute	Description
bool	Boolean values are those which can be assigned true or false
string	Text, the type will be specified in the code similarly
enum	Define an enumeration as a list of enumeration elements in the enum field
int, int8, int16, int32, int64, rune	Integer, the type will be specified in the code similarly
uint, uint8, uint16, uint32, uint64, byte	A unsigned integer, the type will be specified in the code similarly
float32, float64	Single precision floating point format, the type will be specified in the code similarly
struct	The structure in which the fields are specified in value can be used for grouping. Can recursively contain structures