Code maintenance: OS package for file system

- OS custom internal package for file system interaction
- Remove fileManager external dependency
- Closer API to Go's native API on the OS
- Create directories at startup
- Better testability
- Move Unsetenv to os interface

internal/cli/cli.go

@@ -4,29 +4,40 @@ import (
 	"context"
 	"flag"
 	"fmt"
+	"io/ioutil"
 	"net/http"
 	"strings"
 	"time"
 
 	"github.com/qdm12/gluetun/internal/constants"
 	"github.com/qdm12/gluetun/internal/healthcheck"
+	"github.com/qdm12/gluetun/internal/os"
 	"github.com/qdm12/gluetun/internal/params"
 	"github.com/qdm12/gluetun/internal/provider"
 	"github.com/qdm12/gluetun/internal/settings"
 	"github.com/qdm12/gluetun/internal/storage"
 	"github.com/qdm12/gluetun/internal/updater"
-	"github.com/qdm12/golibs/files"
 	"github.com/qdm12/golibs/logging"
 )
 
-func ClientKey(args []string) error {
+func ClientKey(args []string, openFile os.OpenFileFunc) error {
 	flagSet := flag.NewFlagSet("clientkey", flag.ExitOnError)
 	filepath := flagSet.String("path", string(constants.ClientKey), "file path to the client.key file")
 	if err := flagSet.Parse(args); err != nil {
 		return err
 	}
-	fileManager := files.NewFileManager()
-	data, err := fileManager.ReadFile(*filepath)
+	file, err := openFile(*filepath, os.O_RDONLY, 0)
+	if err != nil {
+		return err
+	}
+	data, err := ioutil.ReadAll(file)
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+	if err := file.Close(); err != nil {
+		return err
+	}
 	if err != nil {
 		return err
 	}
@@ -49,17 +60,17 @@ func HealthCheck(ctx context.Context) error {
 	return healthchecker.Check(ctx, url)
 }
 
-func OpenvpnConfig() error {
+func OpenvpnConfig(os os.OS) error {
 	logger, err := logging.NewLogger(logging.ConsoleEncoding, logging.InfoLevel)
 	if err != nil {
 		return err
 	}
-	paramsReader := params.NewReader(logger, files.NewFileManager())
+	paramsReader := params.NewReader(logger, os)
 	allSettings, err := settings.GetAllSettings(paramsReader)
 	if err != nil {
 		return err
 	}
-	allServers, err := storage.New(logger).SyncServers(constants.GetAllServers(), false)
+	allServers, err := storage.New(logger, os).SyncServers(constants.GetAllServers(), false)
 	if err != nil {
 		return err
 	}
@@ -81,7 +92,7 @@ func OpenvpnConfig() error {
 	return nil
 }
 
-func Update(args []string) error {
+func Update(args []string, os os.OS) error {
 	options := settings.Updater{CLI: true}
 	var flushToFile bool
 	flagSet := flag.NewFlagSet("update", flag.ExitOnError)
@@ -110,7 +121,7 @@ func Update(args []string) error {
 	ctx := context.Background()
 	const clientTimeout = 10 * time.Second
 	httpClient := &http.Client{Timeout: clientTimeout}
-	storage := storage.New(logger)
+	storage := storage.New(logger, os)
 	const writeSync = false
 	currentServers, err := storage.SyncServers(constants.GetAllServers(), writeSync)
 	if err != nil {