move db connection process to seperate file

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
+}