Refactor environment variable handling to use value types and add validation for listen host and port

Author: eduardolat

cmd/app/main.go

@@ -13,7 +13,10 @@ import (
 )
 
 func main() {
-	env := config.GetEnv()
+	env, err := config.GetEnv()
+	if err != nil {
+		logger.FatalError("error getting environment variables", logger.KV{"error": err})
+	}
 
 	cr, err := cron.New()
 	if err != nil {
@@ -43,8 +46,12 @@ func main() {
 	app.HidePort = true
 	view.MountRouter(app, servs)
 
-	logger.Info("server started at http://localhost:8085")
-	if err := app.Start(":8085"); err != nil {
+	address := env.PBW_LISTEN_HOST + ":" + env.PBW_LISTEN_PORT
+	logger.Info("server started at http://localhost:"+env.PBW_LISTEN_PORT, logger.KV{
+		"listenHost": env.PBW_LISTEN_HOST,
+		"listenPort": env.PBW_LISTEN_PORT,
+	})
+	if err := app.Start(address); err != nil {
 		logger.FatalError("error starting server", logger.KV{"error": err})
 	}
 }

cmd/changepw/main.go

@@ -14,7 +14,10 @@ import (
 )
 
 func main() {
-	env := config.GetEnv()
+	env, err := config.GetEnv()
+	if err != nil {
+		panic(err)
+	}
 
 	db := database.Connect(env)
 	defer db.Close()

cmd/resetdb/main.go

@@ -28,19 +28,23 @@ func main() {
 		log.Println("Please enter 'yes' or 'no'")
 	}
 
-	env := config.GetEnv()
+	env, err := config.GetEnv()
+	if err != nil {
+		panic(err)
+	}
+
 	db := connectDB(env)
 
-	_, err := db.Exec("DROP SCHEMA public CASCADE; CREATE SCHEMA public;")
+	_, err = db.Exec("DROP SCHEMA public CASCADE; CREATE SCHEMA public;")
 	if err != nil {
 		panic(fmt.Errorf("❌ Could not reset DB: %w", err))
 	}
 
 	log.Println("✅ Database reset")
 }
 
-func connectDB(env *config.Env) *sql.DB {
-	db, err := sql.Open("postgres", *env.PBW_POSTGRES_CONN_STRING)
+func connectDB(env config.Env) *sql.DB {
+	db, err := sql.Open("postgres", env.PBW_POSTGRES_CONN_STRING)
 	if err != nil {
 		panic(fmt.Errorf("❌ Could not connect to DB: %w", err))
 	}

internal/config/env.go

@@ -1,37 +1,45 @@
 package config
 
 import (
-	"github.com/eduardolat/pgbackweb/internal/logger"
+	"sync"
+
+	"github.com/caarlos0/env/v11"
 	"github.com/joho/godotenv"
 )
 
 type Env struct {
-	PBW_ENCRYPTION_KEY       *string
-	PBW_POSTGRES_CONN_STRING *string
+	PBW_ENCRYPTION_KEY       string `env:"PBW_ENCRYPTION_KEY,required"`
+	PBW_POSTGRES_CONN_STRING string `env:"PBW_POSTGRES_CONN_STRING,required"`
+	PBW_LISTEN_HOST          string `env:"PBW_LISTEN_HOST" envDefault:"0.0.0.0"`
+	PBW_LISTEN_PORT          string `env:"PBW_LISTEN_PORT" envDefault:"8085"`
 }
 
+var (
+	getEnvRes  Env
+	getEnvErr  error
+	getEnvOnce sync.Once
+)
+
 // GetEnv returns the environment variables.
 //
 // If there is an error, it will log it and exit the program.
-func GetEnv(disableLogs ...bool) *Env {
-	pickedDisableLogs := len(disableLogs) > 0 && disableLogs[0]
-
-	err := godotenv.Load()
-	if err == nil && !pickedDisableLogs {
-		logger.Info("using .env file")
-	}
-
-	env := &Env{
-		PBW_ENCRYPTION_KEY: getEnvAsString(getEnvAsStringParams{
-			name:       "PBW_ENCRYPTION_KEY",
-			isRequired: true,
-		}),
-		PBW_POSTGRES_CONN_STRING: getEnvAsString(getEnvAsStringParams{
-			name:       "PBW_POSTGRES_CONN_STRING",
-			isRequired: true,
-		}),
-	}
-
-	validateEnv(env)
-	return env
+func GetEnv(disableLogs ...bool) (Env, error) {
+	getEnvOnce.Do(func() {
+		_ = godotenv.Load()
+
+		parsedEnv, err := env.ParseAs[Env]()
+		if err != nil {
+			getEnvErr = err
+			return
+		}
+
+		if err := validateEnv(parsedEnv); err != nil {
+			getEnvErr = err
+			return
+		}
+
+		getEnvRes = parsedEnv
+	})
+
+	return getEnvRes, getEnvErr
 }

internal/config/env_validate.go

@@ -1,4 +1,20 @@
 package config
 
+import (
+	"fmt"
+
+	"github.com/eduardolat/pgbackweb/internal/validate"
+)
+
 // validateEnv runs additional validations on the environment variables.
-func validateEnv(env *Env) {}
+func validateEnv(env Env) error {
+	if !validate.ListenHost(env.PBW_LISTEN_HOST) {
+		return fmt.Errorf("invalid listen address %s", env.PBW_LISTEN_HOST)
+	}
+
+	if !validate.Port(env.PBW_LISTEN_PORT) {
+		return fmt.Errorf("invalid listen port %s, valid values are 1-65535", env.PBW_LISTEN_PORT)
+	}
+
+	return nil
+}