Add gRPC interface function to write settings to file (#1144)

* Add gRPC interface function to write settings to file

* Add example of gRPC config write

client_example/main.go

@@ -90,6 +90,10 @@ func main() {
 	log.Println("calling GetValue(foo)")
 	callGetValue(settingsClient)
 
+	// Write settings to file.
+	log.Println("calling Write()")
+	callWrite(settingsClient)
+
 	// Before we can do anything with the CLI, an "instance" must be created.
 	// We keep a reference to the created instance because we will need it to
 	// run subsequent commands.
@@ -256,6 +260,17 @@ func callGetAll(client settings.SettingsClient) {
 	log.Printf("Settings: %s", getAllResp.GetJsonData())
 }
 
+func callWrite(client settings.SettingsClient) {
+	_, err := client.Write(context.Background(),
+		&settings.WriteRequest{
+			FilePath: path.Join(dataDir, "written-settings.yml"),
+		})
+
+	if err != nil {
+		log.Fatalf("Error writing settings: %s", err)
+	}
+}
+
 func initInstance(client rpc.ArduinoCoreClient) *rpc.Instance {
 	// The configuration for this example client only contains the path to
 	// the data folder.

commands/daemon/settings.go

@@ -86,3 +86,14 @@ func (s *SettingsService) SetValue(ctx context.Context, val *rpc.Value) (*rpc.Se
 
 	return &rpc.SetValueResponse{}, err
 }
+
+// Write to file set in request the settings currently stored in memory.
+// We don't have a Read() function, that's not necessary since we only want one config file to be used
+// and that's picked up when the CLI is run as daemon, either using the default path or a custom one
+// set with the --config-file flag.
+func (s *SettingsService) Write(ctx context.Context, req *rpc.WriteRequest) (*rpc.WriteResponse, error) {
+	if err := configuration.Settings.WriteConfigAs(req.FilePath); err != nil {
+		return nil, err
+	}
+	return &rpc.WriteResponse{}, nil
+}

commands/daemon/settings_test.go

@@ -23,6 +23,7 @@ import (
 
 	"github.com/arduino/arduino-cli/configuration"
 	rpc "github.com/arduino/arduino-cli/rpc/settings"
+	"github.com/arduino/go-paths-helper"
 	"github.com/stretchr/testify/require"
 )
 
@@ -80,3 +81,29 @@ func TestSetValue(t *testing.T) {
 	require.Nil(t, err)
 	require.Equal(t, "bar", configuration.Settings.GetString("foo"))
 }
+
+func TestWrite(t *testing.T) {
+	// Writes some settings
+	val := &rpc.Value{
+		Key:      "foo",
+		JsonData: `"bar"`,
+	}
+	_, err := svc.SetValue(context.Background(), val)
+	require.NoError(t, err)
+
+	tempDir := paths.TempDir()
+	testFolder, _ := tempDir.MkTempDir("testdata")
+
+	// Verifies config files doesn't exist
+	configFile := testFolder.Join("arduino-cli.yml")
+	require.True(t, configFile.NotExist())
+
+	_, err = svc.Write(context.Background(), &rpc.WriteRequest{
+		FilePath: configFile.String(),
+	})
+	require.NoError(t, err)
+
+	// Verifies config file is created.
+	// We don't verify the content since we expect config library, Viper, to work
+	require.True(t, configFile.Exist())
+}

rpc/settings/settings.proto

@@ -30,6 +30,8 @@ service Settings {
   rpc GetValue(GetValueRequest) returns (Value);
   // Set the value of a specific setting.
   rpc SetValue(Value) returns (SetValueResponse);
+  // Writes to file settings currently stored in memory
+  rpc Write(WriteRequest) returns (WriteResponse);
 }
 
 message RawData {
@@ -51,3 +53,12 @@ message GetValueRequest {
 }
 message MergeResponse {}
 message SetValueResponse {}
+
+message WriteRequest {
+  // Path to settings file (e.g. /path/to/arduino-cli.yaml)
+  string filePath = 1;
+}
+
+message WriteResponse {
+  // TODO
+}
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