panic() is not the best way to show error in entrypoints

Author: joonas-fi

cmd/ubackup/encryption.go

@@ -75,9 +75,7 @@ func decryptEntry() *cobra.Command {
 		Short: "Decrypts an encrypted backup file (from stdin) with your private key",
 		Args:  cobra.ExactArgs(1),
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := decryptAndDecompress(args[0], os.Stdin, os.Stdout); err != nil {
-				panic(err)
-			}
+			exitIfError(decryptAndDecompress(args[0], os.Stdin, os.Stdout))
 		},
 	}
 }
@@ -88,9 +86,7 @@ func decryptionKeyGenerateEntry() *cobra.Command {
 		Short: "Generate RSA private key for backup decryption",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := decryptionKeyGenerate(os.Stdout); err != nil {
-				panic(err)
-			}
+			exitIfError(decryptionKeyGenerate(os.Stdout))
 		},
 	}
 }
@@ -101,9 +97,7 @@ func decryptionKeyToEncryptionKeyEntry() *cobra.Command {
 		Short: "Prints encryption key (= public key) of decryption key (= private key)",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := decryptionKeyToEncryptionKey(os.Stdin, os.Stdout); err != nil {
-				panic(err)
-			}
+			exitIfError(decryptionKeyToEncryptionKey(os.Stdin, os.Stdout))
 		},
 	}
 }

cmd/ubackup/main.go

@@ -30,12 +30,10 @@ func main() {
 		Run: func(cmd *cobra.Command, args []string) {
 			rootLogger := logex.StandardLogger()
 
-			if err := runBackup(
+			exitIfError(runBackup(
 				ossignal.InterruptOrTerminateBackgroundCtx(logex.Prefix("main", rootLogger)),
 				rootLogger,
-			); err != nil {
-				panic(err)
-			}
+			))
 		},
 	})
 
@@ -47,10 +45,7 @@ func main() {
 	app.AddCommand(decryptionKeyGenerateEntry())
 	app.AddCommand(decryptionKeyToEncryptionKeyEntry())
 
-	if err := app.Execute(); err != nil {
-		fmt.Fprintln(os.Stderr, err)
-		os.Exit(1)
-	}
+	exitIfError(app.Execute())
 }
 
 func manualEntry() *cobra.Command {
@@ -84,11 +79,12 @@ func manualEntry() *cobra.Command {
 		Run: func(cmd *cobra.Command, args []string) {
 			rootLogger := logex.StandardLogger()
 
-			ctx := ossignal.InterruptOrTerminateBackgroundCtx(logex.Prefix("main", rootLogger))
-
-			if err := manual(ctx, args[0], args[1], os.Stdin, rootLogger); err != nil {
-				panic(err)
-			}
+			exitIfError(manual(
+				ossignal.InterruptOrTerminateBackgroundCtx(rootLogger),
+				args[0],
+				args[1],
+				os.Stdin,
+				rootLogger))
 		},
 	}
 }
@@ -112,9 +108,7 @@ func configValidateEntry() *cobra.Command {
 		Short: "Validates your config file (from stdin)",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := jsonfile.Unmarshal(os.Stdin, &ubconfig.Config{}, true); err != nil {
-				panic(err)
-			}
+			exitIfError(jsonfile.Unmarshal(os.Stdin, &ubconfig.Config{}, true))
 		},
 	}
 }
@@ -128,9 +122,7 @@ func configExampleEntry() *cobra.Command {
 		Short: "Shows you an example config file",
 		Args:  cobra.NoArgs,
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := jsonfile.Marshal(os.Stdout, ubconfig.DefaultConfig(pubkeyFilePath, kitchenSink)); err != nil {
-				panic(err)
-			}
+			exitIfError(jsonfile.Marshal(os.Stdout, ubconfig.DefaultConfig(pubkeyFilePath, kitchenSink)))
 		},
 	}
 
@@ -139,3 +131,9 @@ func configExampleEntry() *cobra.Command {
 
 	return cmd
 }
+
+func exitIfError(err error) {
+	if err != nil {
+		fmt.Fprintln(os.Stderr, err)
+	}
+}

cmd/ubackup/scheduler.go

@@ -79,9 +79,10 @@ func schedulerEntry() *cobra.Command {
 				return nil
 			}
 
-			if err := runScheduler(ctx, backupTime, logex.Prefix("scheduler", rootLogger)); err != nil {
-				panic(err)
-			}
+			exitIfError(runScheduler(
+				ctx,
+				backupTime,
+				logex.Prefix("scheduler", rootLogger)))
 		},
 	})
 
@@ -95,9 +96,8 @@ func schedulerEntry() *cobra.Command {
 				"µbackup",
 				systemdinstaller.Args("scheduler", "run"),
 				systemdinstaller.Docs("https://function61.com/"))
-			if err := systemdinstaller.Install(service); err != nil {
-				panic(err)
-			}
+
+			exitIfError(systemdinstaller.Install(service))
 
 			fmt.Println(systemdinstaller.GetHints(service))
 		},

cmd/ubackup/storage.go

@@ -65,9 +65,7 @@ func storageEntry() *cobra.Command {
 		Short: "List backups from storage for a service",
 		Args:  cobra.ExactArgs(1),
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := ls(args[0]); err != nil {
-				panic(err)
-			}
+			exitIfError(ls(args[0]))
 		},
 	})
 
@@ -76,9 +74,7 @@ func storageEntry() *cobra.Command {
 		Short: "Get backup from storage",
 		Args:  cobra.ExactArgs(1),
 		Run: func(cmd *cobra.Command, args []string) {
-			if err := get(args[0]); err != nil {
-				panic(err)
-			}
+			exitIfError(get(args[0]))
 		},
 	})