Config

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Goal

Make the database path configurable via an environment variable and assemble the complete main function. After this page you have the full runnable server.

Prerequisites

• Create handler — all three handlers wired to the mux

Environment variable config

Hard-coding "items.db" in main means tests and production share the same file path. A single environment variable (ITEMS_DB) fixes that: the caller sets a path; the binary defaults to items.db if the variable is absent.

The complete main.go

Replace main.go with the final version:

package main

import (
	"log"
	"net/http"
	"os"
)

func main() {
	path := os.Getenv("ITEMS_DB")
	if path == "" {
		path = "items.db"
	}
	db, err := openDB(path)
	if err != nil {
		log.Fatal(err)
	}
	store := &Store{db: db}
	mux := http.NewServeMux()
	mux.Handle("GET /items", handleList(store))
	mux.Handle("GET /items/{id}", handleGet(store))
	mux.Handle("POST /items", handleCreate(store))
	log.Println("listening on :8080")
	log.Fatal(http.ListenAndServe(":8080", mux))
}

os.Getenv returns an empty string if the variable is not set — the if path == "" guard applies the default. This pattern avoids importing a config library for a single value.

Checkpoint

Run with a custom path:

ITEMS_DB=/tmp/x.db go run .

Expected output (then Ctrl-C):

2024/01/01 00:00:00 listening on :8080

Verify the file was created at the custom path:

ls /tmp/x.db

Expected:

/tmp/x.db

Run without the variable to confirm the default:

go run .

A fresh items.db is created in the current directory.

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