Fix viper config parsing (#19)

This fixes viper's config parsing to properly read the settings config
and fixes precedence of CLI flags -> config settings -> defaults.

Author: udpatil

config/settings.go

@@ -1,6 +1,8 @@
 package config
 
 import (
+	"bytes"
+	"encoding/json"
 	"fmt"
 	"time"
 
@@ -10,18 +12,18 @@ import (
 
 // Settings holds all CLI-configurable parameters
 type Settings struct {
-	Workers          int           `json:"workers"`
-	TPS              float64       `json:"tps"`
-	StatsInterval    Duration `json:"statsInterval"`
-	BufferSize       int           `json:"bufferSize"`
-	DryRun           bool          `json:"dryRun"`
-	Debug            bool          `json:"debug"`
-	TrackReceipts    bool          `json:"trackReceipts"`
-	TrackBlocks      bool          `json:"trackBlocks"`
-	TrackUserLatency bool          `json:"trackUserLatency"`
-	Prewarm          bool          `json:"prewarm"`
-	RampUp           bool          `json:"rampUp"`
-	ReportPath       string        `json:"reportPath"`
+	Workers          int      `json:"workers,omitempty"`
+	TPS              float64  `json:"tps,omitempty"`
+	StatsInterval    Duration `json:"statsInterval,omitempty"`
+	BufferSize       int      `json:"bufferSize,omitempty"`
+	DryRun           bool     `json:"dryRun,omitempty"`
+	Debug            bool     `json:"debug,omitempty"`
+	TrackReceipts    bool     `json:"trackReceipts,omitempty"`
+	TrackBlocks      bool     `json:"trackBlocks,omitempty"`
+	TrackUserLatency bool     `json:"trackUserLatency,omitempty"`
+	Prewarm          bool     `json:"prewarm,omitempty"`
+	RampUp           bool     `json:"rampUp,omitempty"`
+	ReportPath       string   `json:"reportPath,omitempty"`
 }
 
 // DefaultSettings returns the default configuration values
@@ -83,15 +85,21 @@ func InitializeViper(cmd *cobra.Command) error {
 	return nil
 }
 
-// LoadConfigFile reads and merges the config file into Viper
-func LoadConfigFile(configFile string) error {
-	if configFile == "" {
-		return fmt.Errorf("config file path is required")
+// LoadSettings reads and merges the config file into Viper
+func LoadSettings(settings *Settings) error {
+	if settings == nil {
+		return fmt.Errorf("config settings are required")
 	}
 
-	viper.SetConfigFile(configFile)
-	if err := viper.ReadInConfig(); err != nil {
-		return fmt.Errorf("failed to read config file %s: %w", configFile, err)
+	// settings converted to JSON bytes
+	settingsJSON, err := json.Marshal(settings)
+	if err != nil {
+		return fmt.Errorf("failed to marshal settings: %w", err)
+	}
+
+	viper.SetConfigType("json")
+	if err := viper.ReadConfig(bytes.NewBuffer(settingsJSON)); err != nil {
+		return fmt.Errorf("failed to read config: %w", err)
 	}
 
 	return nil

config/settings_test.go

@@ -1,8 +1,7 @@
 package config
 
 import (
-	"os"
-	"path/filepath"
+	"encoding/json"
 	"testing"
 	"time"
 
@@ -71,8 +70,10 @@ func TestArgumentPrecedence(t *testing.T) {
 			// Reset viper for each test
 			viper.Reset()
 
-			// Create temporary config file
-			configFile := createTempConfigFile(t, tt.configContent)
+			// create Settings struct
+			configSettings := &Settings{}
+			err := json.Unmarshal([]byte(tt.configContent), configSettings)
+			require.NoError(t, err, "Failed to unmarshal config file")
 
 			// Create test command with flags
 			cmd := &cobra.Command{
@@ -102,8 +103,8 @@ func TestArgumentPrecedence(t *testing.T) {
 			// Initialize Viper
 			require.NoError(t, InitializeViper(cmd), "Failed to initialize Viper")
 
-			// Load config file
-			require.NoError(t, LoadConfigFile(configFile), "Failed to load config file")
+			// Load settings
+			require.NoError(t, LoadSettings(configSettings), "Failed to load settings")
 
 			// Resolve settings
 			settings := ResolveSettings()
@@ -138,12 +139,3 @@ func TestDefaultSettings(t *testing.T) {
 		t.Errorf("DefaultSettings mismatch.\nExpected: %+v\nGot: %+v", expected, defaults)
 	}
 }
-
-// Helper function to create temporary config files for testing
-func createTempConfigFile(t *testing.T, content string) string {
-	t.Helper()
-	destination := filepath.Join(t.TempDir(), "test-config.json")
-	err := os.WriteFile(destination, []byte(content), 0644)
-	require.NoError(t, err, "Failed to create temp config file: %v", err)
-	return destination
-}

main.go

@@ -87,17 +87,17 @@ func main() {
 }
 
 func runLoadTest(ctx context.Context, cmd *cobra.Command, args []string) error {
-	// Load config file into Viper
-	if err := config.LoadConfigFile(configFile); err != nil {
-		return fmt.Errorf("failed to load config file: %w", err)
-	}
-
 	// Parse the config file into a config.LoadConfig struct
 	cfg, err := loadConfig(configFile)
 	if err != nil {
 		return fmt.Errorf("failed to load config: %w", err)
 	}
 
+	// Load settings into Viper
+	if err := config.LoadSettings(cfg.Settings); err != nil {
+		return fmt.Errorf("failed to load config file: %w", err)
+	}
+
 	// Get resolved settings from the config package
 	settings := config.ResolveSettings()
 

profiles/autobake_evm_transfer.json

@@ -25,6 +25,7 @@
       "trackBlocks": false,
       "trackUserLatency": false,
       "prewarm": false,
+      "rampUp": false,
       "reportPath": "/home/ubuntu/evm_transfer_report.txt"
     }
   }