Ok. I have properly debug the app and found out that QProcess, QStandardPaths::writableLocation and qgetenv are not working when app is a service. It seems that service functionality is limited. So, I decided to set my app to run at OS startup instead of a service. Now, it works well. The issue is resolved. Thanks.

I will debug it again because it seems some code is skipped when running it as a service. Thank you.

In the Event Viewer it reports: The start method executing....
But for some reason everything below logMessage() does not execute.

logFile->open(QIODevice::WriteOnly | QIODevice::Append);

Why don't you test this result? At the moment you would not know whether anything is executing after logMessage(). That is all I am saying.

It only executes the QtServiceBase methods. I can show you the example, you will see it one moment.

When I hardcoded the file path to: "C:\\Users\\cobra\\AppData\\Local\\InsuranceService\\Log\\text.txt" it successfully created the file. It seems the issue is with: QStandardPaths::writableLocation(QStandardPaths::DataLocation) but I need to debug it again. Thanks.

I already tried to log every step, anything after myCustomMessage("C:\\Users\\cobra\\AppData\\Local\\InsuranceService\\Log\\Test.txt"); will NOT execute. At this moment I do not know what is the reason for such behaviour. The app runs just fine but when it is the service it does nothing.

I just run InsuranceService.exe -exec in cmd and it works beause I see the file is created and data is written there as well. When I run NET START InsuranceService command, the service is started and running but no file is created.

Also, I add my test method to QtServiceBase class and call it, then the file automatically creates when I start my service. Additionally, the program has the admin privileges.

I think the issue could be with the static Qt build, which could take some internal files and override them. I had some similar issues with QFtp class. I will try to use Qt shared build and provide all dlls components.

But for some reason everything below logMessage() does not execute

logFile->open(QIODevice::WriteOnly | QIODevice::Append);

How do you know this does not execute? The very first thing I would do is check the return result and report details of any failure.

Could you have a file permission issue? You have to be careful about the paths you pass to open and the permissions you are currently executing under.

void QtServiceBase::myCustomMessage(QString path)
{
    QFile *file = new QFile(path);
    file->open(QIODevice::WriteOnly);
    file->write("This is just a test example....");
    file->close();
    file->deleteLater();
}

And in InsuranceService class I call my myCustomMessage() test method.

void InsuranceService::start()
{
    logMessage("The start method executing....", QtServiceBase::Success, 0, 0);
    myCustomMessage("C:\\Users\\cobra\\AppData\\Local\\InsuranceService\\Log\\Test.txt");
}

Now it creates the .txt file in the service! So, I was right. The issue is with the wrong instance.
Have anyone tried the QtService to share some details about this issue? Thanks.

void InsuranceService::start()
{
    logMessage("The start method executing....", QtServiceBase::Success, 0, 0);
    QFile *logFile = new QFile(ServiceLogger::getLogPath());
    logFile->open(QIODevice::WriteOnly | QIODevice::Append);
    ServiceLogger::writeLog(logFile, QString("Test...").toUtf8());
    logFile->close();
    logFile->deleteLater();
}

In the Event Viewer it reports: The start method executing....
But for some reason everything below logMessage() does not execute. The log file does not exists which should be created. It could be the issue that logMessage() runs on one instance and QFile creates/runs on another instance. I need somehow to connect to the right instance.

Additionally, I will create the logger to check what exectly executes in the start method.

I already tried node-windows but it fails for me. That's why I decided to write my own service.

I think, I know what is wrong. I found a similar issue: https://stackoverflow.com/questions/10027306/windows-service-doesnt-execute-onstart

All you should really do in the start event is fire up a worker thread that will run as long as your service is active and do the actual processing. You can use a BackgroundWorker component to simplify this. When the service is stopped you do any necessary cleanup, and terminate the background thread.

I should create the worker class and a thread and do all processing there. start() method should call Worker class with QThread, stop() method should stop the thread and clear all resources. I think, the app event loop goes out of scope or something else occurs when in a service mode. Thanks.

Yes, you are right. So, how to provide to this service the access to all these things: environment variables (PATH etc), console IO, etc?

There are a lot of other services which do something, for example Google Update service etc.

Thanks.

What can be going wrong is very dependent on exactly what your npm and app instance needs.