Worker: blender-render command, make the blendfile parameter optional

Only include the `blendfile` parameter if it is not empty. This makes it
possible to pass a Python script that loads/constructs the blend file,
instead of loading one directly.

CHANGELOG.md

@@ -8,6 +8,7 @@ bugs in actually-released versions.
 
 - Add MQTT support. Flamenco Manager can now send internal events to an MQTT broker.
 - Simplify the preview video filename when a complex set of frames rendered ([#104285](https://projects.blender.org/studio/flamenco/issues/104285)). Instead of `video-1, 4, 10.mp4` it is now simply `video-1-10.mp4`.
+- Make the `blendfile` parameter of a `blender-render` command optional. This makes it possible to pass, for example, a Python file that loads/constructs the blend file, instead of loading one straight from disk.
 
 ## 3.4 - released 2024-01-12
 

internal/worker/command_blender.go

@@ -101,7 +101,12 @@ func (ce *CommandExecutor) cmdBlenderRenderCommand(
 
 	cliArgs := make([]string, 0)
 	cliArgs = append(cliArgs, parameters.argsBefore...)
-	cliArgs = append(cliArgs, parameters.blendfile)
+	if parameters.blendfile != "" {
+		// Only include the blendfile if the parameter is not empty. This makes it
+		// possible to pass a Python script that loads/constructs the blend file,
+		// instead of loading one explicitly here.
+		cliArgs = append(cliArgs, parameters.blendfile)
+	}
 	cliArgs = append(cliArgs, parameters.args...)
 	execCmd := ce.cli.CommandContext(ctx, parameters.exe, cliArgs...)
 	if execCmd == nil {
@@ -132,9 +137,9 @@ func cmdBlenderRenderParams(logger zerolog.Logger, cmd api.Command) (BlenderPara
 		logger.Warn().Interface("command", cmd).Msg("invalid 'argsBefore' parameter")
 		return parameters, NewParameterInvalidError("argsBefore", cmd, "cannot convert to list of strings")
 	}
-	if parameters.blendfile, ok = cmdParameter[string](cmd, "blendfile"); !ok || parameters.blendfile == "" {
+	if parameters.blendfile, ok = cmdParameter[string](cmd, "blendfile"); !ok {
-		logger.Warn().Interface("command", cmd).Msg("missing 'blendfile' parameter")
+		logger.Warn().Interface("command", cmd).Msg("invalid 'blendfile' parameter")
-		return parameters, NewParameterMissingError("blendfile", cmd)
+		return parameters, NewParameterInvalidError("blendfile", cmd, "cannot convert to string")
 	}
 	if parameters.args, ok = cmdParameterAsStrings(cmd, "args"); !ok {
 		logger.Warn().Interface("command", cmd).Msg("invalid 'args' parameter")

internal/worker/command_blender_test.go

@@ -79,6 +79,30 @@ func TestCmdBlenderCliArgsInExeParameter(t *testing.T) {
 	assert.Equal(t, ErrNoExecCmd, err, "nil *exec.Cmd should result in ErrNoExecCmd")
 }
 
+func TestCmdBlenderNoBlendfile(t *testing.T) {
+	mockCtrl := gomock.NewController(t)
+	defer mockCtrl.Finish()
+
+	ce, mocks := testCommandExecutor(t, mockCtrl)
+
+	taskID := "1d54c6fe-1242-4c8f-bd63-5a09e358d7b6"
+	cmd := api.Command{
+		Name: "blender",
+		Parameters: map[string]interface{}{
+			"exe":        "/path/to/blender",
+			"argsBefore": []string{"--background"},
+			"blendfile":  "", // Empty blendfile should be skipped.
+			"args":       []string{"--render-output", "/frames"},
+		},
+	}
+
+	cliArgs := []string{"--background", "--render-output", "/frames"}
+	mocks.cli.EXPECT().CommandContext(gomock.Any(), "/path/to/blender", cliArgs).Return(nil)
+
+	err := ce.cmdBlenderRender(context.Background(), zerolog.Nop(), taskID, cmd)
+	assert.Equal(t, ErrNoExecCmd, err, "nil *exec.Cmd should result in ErrNoExecCmd")
+}
+
 func TestProcessLineBlender(t *testing.T) {
 	ctx := context.Background()
 	mockCtrl := gomock.NewController(t)