TUN-3558: cloudflared allows empty config files

cmd/cloudflared/config/configuration.go

@@ -2,6 +2,7 @@ package config
 
 import (
 	"fmt"
+	"io"
 	"net/url"
 	"os"
 	"path/filepath"
@@ -392,6 +393,10 @@ func ReadConfigFile(c *cli.Context, log logger.Service) (*configFileSettings, er
 	}
 	defer file.Close()
 	if err := yaml.NewDecoder(file).Decode(&configuration); err != nil {
+		if err == io.EOF {
+			log.Errorf("Configuration file %s was empty", configFile)
+			return &configuration, nil
+		}
 		return nil, errors.Wrap(err, "error parsing YAML in config file at "+configFile)
 	}
 	configuration.sourceFile = configFile

cmd/cloudflared/config/manager.go

@@ -1,6 +1,7 @@
 package config
 
 import (
+	"io"
 	"os"
 
 	"github.com/cloudflare/cloudflared/logger"
@@ -27,7 +28,7 @@ type FileManager struct {
 	notifier   Notifier
 	configPath string
 	logger     logger.Service
-	ReadConfig func(string) (Root, error)
+	ReadConfig func(string, logger.Service) (Root, error)
 }
 
 // NewFileManager creates a config manager
@@ -59,7 +60,7 @@ func (m *FileManager) Start(notifier Notifier) error {
 
 // GetConfig reads the yaml file from the disk
 func (m *FileManager) GetConfig() (Root, error) {
-	return m.ReadConfig(m.configPath)
+	return m.ReadConfig(m.configPath, m.logger)
 }
 
 // Shutdown stops the watcher
@@ -67,7 +68,7 @@ func (m *FileManager) Shutdown() {
 	m.watcher.Shutdown()
 }
 
-func readConfigFromPath(configPath string) (Root, error) {
+func readConfigFromPath(configPath string, log logger.Service) (Root, error) {
 	if configPath == "" {
 		return Root{}, errors.New("unable to find config file")
 	}
@@ -80,6 +81,10 @@ func readConfigFromPath(configPath string) (Root, error) {
 
 	var config Root
 	if err := yaml.NewDecoder(file).Decode(&config); err != nil {
+		if err == io.EOF {
+			log.Errorf("Configuration file %s was empty", configPath)
+			return Root{}, nil
+		}
 		return Root{}, errors.Wrap(err, "error parsing YAML in config file at "+configPath)
 	}
 

cmd/cloudflared/config/manager_test.go

@@ -57,7 +57,7 @@ func TestConfigChanged(t *testing.T) {
 			},
 		},
 	}
-	configRead := func(configPath string) (Root, error) {
+	configRead := func(configPath string, log logger.Service) (Root, error) {
 		return *c, nil
 	}
 	wait := make(chan struct{})