Merging JSON structures in go without explicit struct mappings

main.go

package main

import (
	"encoding/json"
	"fmt"
)

func main() {
	inputJSON := `{"environment": "production", "runbook":"http://url","message":"there is a problem"}`
	out := map[string]interface{}{}
	json.Unmarshal([]byte(inputJSON), &out)

	out["name"] = "thomas"
	out["command"] = "sudo make me a sammich"
	out["status"] = "ready"
	out["environment"] = "stage"

	outputJSON, _ := json.Marshal(out)

	fmt.Printf("%s\n", outputJSON)
}