move db connection process to seperate file

golang/cmd/frontend/main.go

@@ -2,11 +2,8 @@ package main
 
 import (
 	"crowsnest/internal/model/database"
-	"database/sql"
-	"fmt"
 	"log"
 	"net/http"
-	"os"
 
 	_ "github.com/lib/pq"
 )
@@ -16,35 +13,9 @@ type App struct {
 }
 
 func main() {
-	// collect environement variables
+	db, err := database.DbConnection()
-	dbPass := os.Getenv("DB_PASS")
-	if dbPass == "" {
-		log.Fatal("empty DB_PASS")
-	}
-	dbHost := os.Getenv("DB_HOST")
-	if dbHost == "" {
-		log.Fatal("empty DB_HOST")
-	}
-	dbPort := os.Getenv("DB_PORT")
-	if dbPort == "" {
-		dbPort = "5432"
-	}
-	dbUser := os.Getenv("DB_USER")
-	if dbUser == "" {
-		dbUser = "postgres"
-	}
-	dbName := os.Getenv("DB_NAME")
-
-	// connect to database
-	databaseURL := fmt.Sprintf("user=%s password=%s dbname=%s host=%s port=%s sslmode=disable",
-		dbUser, dbPass, dbName, dbHost, dbPort)
-	db, err := sql.Open("postgres", databaseURL)
 	if err != nil {
-		log.Fatal(err)
+		log.Fatal("failed to connect to database due to", err.Error())
-	}
-	defer db.Close()
-	if err = db.Ping(); err != nil {
-		log.Fatal(err)
 	}
 
 	// define app
@@ -54,10 +25,10 @@ func main() {
 
 	// start web server
 	server := http.Server{
-		Addr:    ":8080",
+		Addr:    ":80",
 		Handler: app.routes(),
 	}
 
-	log.Println("server started, listening on :8080")
+	log.Println("server started, listening on :80")
 	server.ListenAndServe()
 }

golang/internal/model/database/connect.go

@@ -0,0 +1,45 @@
+package database
+
+import (
+	"database/sql"
+	"errors"
+	"fmt"
+	"os"
+)
+
+// Will try to connect to the database defined by the env variables. If the
+// connection fails a error will be returned. Ensure that the returned sql.DB
+// object is closed after use.
+func DbConnection() (*sql.DB, error) {
+	// collect environement variables
+	dbPass := os.Getenv("DB_PASS")
+	if dbPass == "" {
+		return nil, errors.New("empty env. variable DB_PASS")
+	}
+	dbHost := os.Getenv("DB_HOST")
+	if dbHost == "" {
+		return nil, errors.New("empty env. variable DB_HOST")
+	}
+	dbPort := os.Getenv("DB_PORT")
+	if dbPort == "" {
+		dbPort = "5432"
+	}
+	dbUser := os.Getenv("DB_USER")
+	if dbUser == "" {
+		dbUser = "postgres"
+	}
+	dbName := os.Getenv("DB_NAME")
+
+	// connect to database
+	databaseURL := fmt.Sprintf("user=%s password=%s dbname=%s host=%s port=%s sslmode=disable",
+		dbUser, dbPass, dbName, dbHost, dbPort)
+	db, err := sql.Open("postgres", databaseURL)
+	if err != nil {
+		return nil, err
+	}
+	if err = db.Ping(); err != nil {
+		return nil, err
+	}
+
+	return db, nil
+}