From 268e7127eedca369d7404f9d83c78c643170bee1 Mon Sep 17 00:00:00 2001
From: Karan Sharma <hello@mrkaran.dev>
Date: Mon, 21 Mar 2022 20:56:00 +0530
Subject: [PATCH] fix: dont error out on sample config error

If the user doesn't provide any config file, the program should
still continue and attempt to read config entirely from env vars.

Previous implementation had a flaw where if no config file was present
(not even sample config) then the program would exit (with fatal).
---
 cmd/init.go | 19 +++++++++++--------
 cmd/main.go | 11 +++++++++--
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/cmd/init.go b/cmd/init.go
index ab4cc0e..457acd9 100644
--- a/cmd/init.go
+++ b/cmd/init.go
@@ -18,7 +18,7 @@ import (
 )
 
 // initLogger initializes logger instance.
-func initLogger(ko *koanf.Koanf) *logrus.Logger {
+func initLogger() *logrus.Logger {
 	logger := logrus.New()
 
 	logger.SetFormatter(&logrus.TextFormatter{
@@ -26,16 +26,11 @@ func initLogger(ko *koanf.Koanf) *logrus.Logger {
 		DisableLevelTruncation: true,
 	})
 
-	// Enable debug mode if specified.
-	if ko.String("app.log") == "debug" {
-		logger.SetLevel(logrus.DebugLevel)
-	}
-
 	return logger
 }
 
 // initConfig loads config to `ko` object.
-func initConfig(cfgDefault string, envPrefix string) (*koanf.Koanf, error) {
+func initConfig(lo *logrus.Logger, cfgDefault string, envPrefix string) (*koanf.Koanf, error) {
 	var (
 		ko = koanf.New(".")
 		f  = flag.NewFlagSet("front", flag.ContinueOnError)
@@ -57,11 +52,19 @@ func initConfig(cfgDefault string, envPrefix string) (*koanf.Koanf, error) {
 	}
 
 	// Load the config files from the path provided.
+	lo.WithField("path", *cfgPath).Info("attempting to load config from file")
+
 	err = ko.Load(file.Provider(*cfgPath), toml.Parser())
 	if err != nil {
-		return nil, err
+		// If the default config is not present, print a warning and continue reading the values from env.
+		if *cfgPath == cfgDefault {
+			lo.WithError(err).Warn("unable to open sample config file")
+		} else {
+			return nil, err
+		}
 	}
 
+	lo.Info("attempting to read config from env vars")
 	// Load environment variables if the key is given
 	// and merge into the loaded config.
 	if envPrefix != "" {
diff --git a/cmd/main.go b/cmd/main.go
index 9d14ec5..9f83433 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -25,20 +25,27 @@ type App struct {
 }
 
 func main() {
+	// Initialise logger.
+	lo := initLogger()
+
 	// Initialise and load the config.
-	ko, err := initConfig("config.sample.toml", "CALERT_")
+	ko, err := initConfig(lo, "config.sample.toml", "CALERT_")
 	if err != nil {
 		// Need to `panic` since logger can only be initialised once config is initialised.
 		panic(err.Error())
 	}
 
 	var (
-		lo       = initLogger(ko)
 		metrics  = initMetrics()
 		provs    = initProviders(ko, lo, metrics)
 		notifier = initNotifier(ko, lo, provs)
 	)
 
+	// Enable debug mode if specified.
+	if ko.String("app.log") == "debug" {
+		lo.SetLevel(logrus.DebugLevel)
+	}
+
 	app := &App{
 		lo:       lo,
 		notifier: notifier,