Add support for init with custom config file (#45)

config/config.go

@@ -21,13 +21,15 @@ import (
 // Parameters:
 //   - viperEnvPrefix : The prefix used for environment variables that `Viper` should consider
 //     while initializing configurations.
+//   - configPath : The path to the configuration file. If not provided, search for the default
+//     config file under current directory or `config` subfolder.
 //
 // Panics:
 //   - If any part of the initialization fails, this function will panic, causing the application
 //     to terminate abruptly.
-func MustInit(viperEnvPrefix string) {
+func MustInit(viperEnvPrefix string, configPath ...string) {
 	// Delegates to the shared initialization logic with no context for graceful shutdown.
-	mustInit(viperEnvPrefix, nil, nil)
+	mustInit(viperEnvPrefix, nil, nil, configPath...)
 }
 
 // MustInitWithCtx carries out the same initializations as `MustInit` except for support for
@@ -38,8 +40,11 @@ func MustInit(viperEnvPrefix string) {
 //   - wg: The wait group to track goroutines for shutdown synchronization.
 //   - viperEnvPrefix : The prefix used for environment variables that `Viper` should consider
 //     while initializing configurations.
-func MustInitWithCtx(ctx context.Context, wg *sync.WaitGroup, viperEnvPrefix string) {
-	mustInit(viperEnvPrefix, ctx, wg)
+//   - configPath : The path to the configuration file. If not provided, search for the default
+//     config file under current directory or `config` subfolder.
+func MustInitWithCtx(
+	ctx context.Context, wg *sync.WaitGroup, viperEnvPrefix string, configPath ...string) {
+	mustInit(viperEnvPrefix, ctx, wg, configPath...)
 }
 
 // mustInit is the internal function responsible for the core initialization steps.
@@ -48,10 +53,11 @@ func MustInitWithCtx(ctx context.Context, wg *sync.WaitGroup, viperEnvPrefix str
 //
 // Important: The order in which initializations are performed is critical due to
 // dependencies between components.
-func mustInit(viperEnvPrefix string, ctx context.Context, wg *sync.WaitGroup) {
+func mustInit(
+	viperEnvPrefix string, ctx context.Context, wg *sync.WaitGroup, configPath ...string) {
 	// Initialize `Viper` to read configurations from a file or environment variables.
 	// The provided prefix is used to match and bind environment variables to config keys.
-	viper.MustInit(viperEnvPrefix)
+	viper.MustInit(viperEnvPrefix, configPath...)
 
 	// Initialize metrics collection based on the configurations loaded into `Viper`.
 	// Metrics are typically used for monitoring application performance.

viper/viper.go

@@ -7,7 +7,9 @@ import (
 	"github.com/spf13/viper"
 )
 
-var envKeyPrefix string // environment variable prefix
+var (
+	envKeyPrefix string // environment variable prefix
+)
 
 func initEnv(envPrefix string) {
 	envKeyPrefix = strings.ToUpper(envPrefix + "_")
@@ -22,17 +24,23 @@ func initEnv(envPrefix string) {
 // MustInit inits viper with provided env var prefix.
 //
 // Note that it will panic and exit if any error happens.
-func MustInit(envPrefix string) {
+func MustInit(envPrefix string, configPath ...string) {
+	logger := logrus.WithField("envPrefix", envPrefix)
 	initEnv(envPrefix)
 
-	// Read config file from current directory or under config folder.
-	viper.SetConfigName("config")
-	viper.AddConfigPath(".")
-	viper.AddConfigPath("./config")
+	if len(configPath) > 0 {
+		logger = logger.WithField("customConfig", configPath[0])
+		viper.SetConfigFile(configPath[0])
+	} else {
+		// Read config file from current directory or under config folder.
+		viper.SetConfigName("config")
+		viper.AddConfigPath(".")
+		viper.AddConfigPath("./config")
+	}
 
 	if err := viper.ReadInConfig(); err != nil {
-		logrus.WithError(err).Fatal("Failed to read config to initialize viper")
+		logger.WithError(err).Fatal("Failed to read config to initialize viper")
 	}
 
-	logrus.Info("Viper initialized")
+	logger.Info("Viper initialized")
 }