How to Validate Configuration at Startup in Go

Validate configuration at startup by checking required environment variables or flags and exiting immediately if they are missing or invalid. This ensures the application fails fast with a clear error message rather than crashing later during execution.

package main

import (
	"fmt"
	"os"
)

func main() {
	if port := os.Getenv("PORT"); port == "" {
		fmt.Fprintln(os.Stderr, "error: PORT environment variable is required")
		os.Exit(1)
	}
	// Application logic continues here
	fmt.Println("Configuration validated, starting server...")
}

Validating configuration at startup in Go checks your app's settings before it runs to ensure everything is correct. If a required setting is missing, the app stops immediately and tells you exactly what is wrong. It is like checking your car's oil and gas before driving to avoid breaking down on the highway.