printLoadedConf modified to only print explicitly set config values (via env or config file)

internal/config/load.go

@@ -3,12 +3,35 @@ package config
 import (
 	"fmt"
 	"log/slog"
+	"os"
 	"strings"
 
 	"github.com/joho/godotenv"
 	"github.com/spf13/viper"
 )
 
+// envKeyReplacer turns a dotted key into its environment variable's suffix
+// (logging.level to LOGGING_LEVEL, once upper-cased).
+var envKeyReplacer = strings.NewReplacer(".", "_")
+
+// envVarName returns the environment variable that sets key, e.g.
+// JOBSEARCH_LOGGING_LEVEL for logging.level.
+func envVarName(key string) string {
+	return EnvPrefix + "_" + strings.ToUpper(envKeyReplacer.Replace(key))
+}
+
+// isExplicitlySet reports whether key's value in Viper was set by the config
+// file or by its environment variable, rather than coming from its default.
+// As Viper does, it ignores an empty environment variable. Values set with
+// viper.Set (e.g. by StoreValue) are not counted.
+func isExplicitlySet(key string) bool {
+	if viper.InConfig(key) {
+		return true
+	}
+	value, ok := os.LookupEnv(envVarName(key))
+	return ok && value != ""
+}
+
 // loadEnv loads environment variables from a .env file in the working
 // directory.
 func loadEnv() error {
@@ -37,7 +60,7 @@ func loadConfig(cfgFile string) error {
 	LoadDefaultConfig()
 
 	viper.SetEnvPrefix(EnvPrefix)
-	viper.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
+	viper.SetEnvKeyReplacer(envKeyReplacer)
 	viper.AutomaticEnv() // read in environment variables that match
 
 	err := viper.ReadInConfig()