Simple example how to merge JSON files.

config.go

package main

import (
	"log"
	"fmt"
	"encoding/json"
)

var conf1 = `
{
 	"name": "my-app"
}
`

var conf2 = `
{
	"port": ":3000"
}
`

type Config struct {
	Name	string
	Port	string
}

func main() {
	c := &Config{}
	
	if err := json.Unmarshal([]byte(conf1), c); err != nil {
		log.Fatal(err)
	}
	if err := json.Unmarshal([]byte(conf2), c); err != nil {
		log.Fatal(err)	
	}
	
	fmt.Printf("%#v", c)	
}