Add the executable dir to the config load path

In adwatchd we would like to use the executable directory as the default
config path.

Update the config API to add the executable path to the config search
path, after all the other paths.

internal/config/config.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"os"
+	"path/filepath"
 
 	"github.com/fsnotify/fsnotify"
 	"github.com/sirupsen/logrus"
@@ -54,6 +56,14 @@ func Init(name string, rootCmd cobra.Command, vip *viper.Viper, configChanged fu
 		vip.AddConfigPath("./")
 		vip.AddConfigPath("$HOME/")
 		vip.AddConfigPath("/etc/")
+
+		// Add the executable path to the config search path.
+		binPath, err := os.Executable()
+		if err != nil {
+			log.Warningf(context.Background(), i18n.G("Failed to get current executable path, not adding it as a config dir: %v"), err)
+		} else {
+			vip.AddConfigPath(filepath.Dir(binPath))
+		}
 	}
 
 	if err := vip.ReadInConfig(); err != nil {

internal/config/config_test.go

@@ -86,14 +86,15 @@ func TestSetVerboseMode(t *testing.T) {
 
 func TestInit(t *testing.T) {
 	tests := map[string]struct {
-		withValueFlagSet  bool
-		noVerboseFlag     bool
-		noConfigFlag      bool
-		withConfigFlagSet string
-		withConfigEnv     bool
-		configFileContent string
-		notInConfigDir    bool
-		changeConfigWith  string
+		withValueFlagSet   bool
+		noVerboseFlag      bool
+		noConfigFlag       bool
+		withConfigFlagSet  string
+		withConfigEnv      bool
+		withConfigInExeDir bool
+		configFileContent  string
+		notInConfigDir     bool
+		changeConfigWith   string
 
 		errFromCallbackOn int
 
@@ -108,6 +109,12 @@ func TestInit(t *testing.T) {
 			configFileContent: "value: filecontentvalue",
 			want:              "filecontentvalue", wantCallbackCalled: 1,
 		},
+		"Load configuration from executable dir": {
+			configFileContent:  "value: filecontentvalue",
+			withConfigInExeDir: true,
+			notInConfigDir:     true,
+			want:               "filecontentvalue", wantCallbackCalled: 1,
+		},
 		"No config flag set before Init is call is ignored": {
 			noConfigFlag:       true,
 			wantCallbackCalled: 1,
@@ -170,6 +177,13 @@ func TestInit(t *testing.T) {
 		tc := tc
 		t.Run(name, func(t *testing.T) {
 			configDir := t.TempDir()
+
+			if tc.withConfigInExeDir {
+				exePath, err := os.Executable()
+				require.NoError(t, err, "Setup: can't get executable path")
+				configDir = filepath.Dir(exePath)
+			}
+
 			if !tc.notInConfigDir {
 				chDir(t, configDir)
 			}