Added simple configuration options

cmd/api-server/main.go

@@ -3,10 +3,13 @@ package main
 import (
 	"context"
 	"errors"
+	"flag"
+	"fmt"
 	"log/slog"
 	"net/http"
 	"os"
 	"os/signal"
+	"strconv"
 	"syscall"
 	"time"
 
@@ -16,6 +19,9 @@ import (
 )
 
 type Config struct {
+	Environment  string
+	Port         int
+	OTLPEndpoint string
 }
 
 func main() {
@@ -30,21 +36,17 @@ func main() {
 
 func run(serviceName string, serviceVersion string) error {
 	_ = godotenv.Load(".env")
-
+	setupLogging()
-	baseHandler := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
-		Level: slog.LevelInfo,
-	})
-	traceHandler := &telemetry.TraceHandler{Handler: baseHandler}
-	logger := slog.New(traceHandler)
-	slog.SetDefault(logger)
 
 	slog.Info("Starting service", slog.String("service", serviceName), slog.String("version", serviceVersion))
 
+	cfg := loadConfig()
+
 	telCfg := telemetry.Config{
 		ServiceName:    serviceName,
 		ServiceVersion: serviceVersion,
-		Endpoint:       "localhost:4317",
+		Endpoint:       cfg.OTLPEndpoint,
-		Environment:    "development",
+		Environment:    cfg.Environment,
 	}
 	shutdownTelemetry, err := telemetry.Init(context.Background(), telCfg)
 	if err != nil {
@@ -60,17 +62,7 @@ func run(serviceName string, serviceVersion string) error {
 		}
 	}()
 
-	cfg := router.Config{}
+	srv := makeServer(cfg)
-	mux := router.NewMux(cfg)
-
-	srv := &http.Server{
-		Addr:         ":8080",
-		Handler:      mux,
-		ReadTimeout:  5 * time.Second,
-		WriteTimeout: 10 * time.Second,
-		IdleTimeout:  120 * time.Second,
-	}
-
 	go func() {
 		slog.Info("Starting http server", "addr", srv.Addr)
 		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
@@ -95,3 +87,66 @@ func run(serviceName string, serviceVersion string) error {
 	slog.Info("Service shutdown successful!")
 	return nil
 }
+
+func setupLogging() {
+	baseHandler := slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
+		Level: slog.LevelInfo,
+	})
+
+	traceHandler := &telemetry.TraceHandler{Handler: baseHandler}
+
+	logger := slog.New(traceHandler)
+	slog.SetDefault(logger)
+}
+
+func loadConfig() *Config {
+	envFlag := flag.String("env", "development", "environment to use")
+	portFlag := flag.Int("port", 8080, "port to listen on")
+	otlpEndpointFlag := flag.String("otlp-endpoint", "localhost:4317", "otlp endpoint")
+
+	flag.Parse()
+
+	cfg := &Config{
+		Environment:  *envFlag,
+		Port:         *portFlag,
+		OTLPEndpoint: *otlpEndpointFlag,
+	}
+
+	assignStringFromEnv("DTTMR_ENVIRONMENT", &cfg.Environment)
+	assignIntFromEnv("DTTMR_PORT", &cfg.Port)
+	assignStringFromEnv("DTTMR_OTLP_ENDPOINT", &cfg.OTLPEndpoint)
+
+	return cfg
+}
+
+func assignStringFromEnv(key string, target *string) {
+	if val, exists := os.LookupEnv(key); exists {
+		*target = val
+	}
+}
+
+func assignIntFromEnv(key string, target *int) {
+	if val, exists := os.LookupEnv(key); exists {
+		parsed, err := strconv.Atoi(val)
+		if err != nil {
+			slog.Error("Failed to parse environment variable", slog.String("var", key), slog.Any("error", err))
+		} else {
+			*target = parsed
+		}
+	}
+}
+
+func makeServer(cfg *Config) *http.Server {
+	routerConfig := router.Config{}
+	mux := router.NewMux(routerConfig)
+
+	srv := &http.Server{
+		Addr:         fmt.Sprintf(":%d", cfg.Port),
+		Handler:      mux,
+		ReadTimeout:  5 * time.Second,
+		WriteTimeout: 10 * time.Second,
+		IdleTimeout:  120 * time.Second,
+	}
+
+	return srv
+}