Programmatically running `npm run build` does not generate `index.html` for Angular 8 app

Question

I want to build my Angular 8 application programmatically for an automated process and using following C# method.

private bool RunBuildProd(string angularAppFolder)
{
            try
            {
                ProcessStartInfo objPI = new ProcessStartInfo(@"C:\Program Files\Nodejs\npm.cmd", $"run build");
                // ProcessStartInfo objPI = new ProcessStartInfo(@"cmd.exe", $"/c npm run build"); // Also tried this one
                objPI.WorkingDirectory = angularAppFolder;
                objPI.RedirectStandardError = true;
                objPI.RedirectStandardOutput = true;
                objPI.UseShellExecute = false;
                objPI.CreateNoWindow = true;
                objPI.WindowStyle = ProcessWindowStyle.Hidden;

                Process objProcess = Process.Start(objPI);
                string error = objProcess.StandardError.ReadToEnd();
                string output = objProcess.StandardOutput.ReadToEnd();

                objProcess.WaitForExit();
                return (objProcess.ExitCode == 0);
            }
            catch (Exception ex)
            {
                return false;
            }
}

When executing above method, I am facing 2 issues:

1. It does not generate index.html file under dist folder when running below method. Note: if I run "npm run build" command on cmd.exe directly, it generates index.html.
2. It does not exit the process for long time and I have to kill it.

What am I missing and How do I resolve it?

Note: I have already ran "npm install" prior to running above method.

UPDATE: Below is the updated code based on answer from Serg, for Avoiding deadlock on read/write of stdout & stderr...

private bool RunBuildProd(string angularAppFolder)
{
    try
    {
        // ProcessStartInfo objPI = new ProcessStartInfo(@"cmd.exe", $"/c npm run build"); // Also tried this one
        ProcessStartInfo objPI = new ProcessStartInfo(@"C:\Program Files\Nodejs\npm.cmd", $"run build");
        objPI.WorkingDirectory = angularAppFolder;
        objPI.RedirectStandardError = true;
        objPI.RedirectStandardOutput = true;
        objPI.UseShellExecute = false;
        objPI.CreateNoWindow = true;
        objPI.WindowStyle = ProcessWindowStyle.Hidden;

        StringBuilder sbOutput = new StringBuilder();
        StringBuilder sbError = new StringBuilder();

        using (AutoResetEvent outputWaitHandle = new AutoResetEvent(false))
        using (AutoResetEvent errorWaitHandle = new AutoResetEvent(false))
        {
            Process objProcess = Process.Start(objPI);

            objProcess.OutputDataReceived += (sender, e) => {
                if (e.Data == null)
                {
                    outputWaitHandle.Set();
                }
                else
                {
                    sbOutput.AppendLine(e.Data);
                }
            };
            objProcess.ErrorDataReceived += (sender, e) =>
            {
                if (e.Data == null)
                {
                    errorWaitHandle.Set();
                }
                else
                {
                    sbError.AppendLine(e.Data);
                }
            };

            objProcess.BeginOutputReadLine();
            objProcess.BeginErrorReadLine();
            objProcess.WaitForExit();
            int timeout = 42000;
            if (outputWaitHandle.WaitOne(timeout) &&
                errorWaitHandle.WaitOne(timeout))
            {
                // Process completed. Check process.ExitCode here.
                return (objProcess.ExitCode == 0);
            }
            else
            {
                // Timed out.
                return (objProcess.ExitCode == 0);
            }
        }
    }
    catch (Exception ex)
    {
        return false;
    }
}

Answer 1

Looks like deadlock due to redirection of both stdout & stderr. Possible solutions may be found here

• Started process hangs when redirected output is relatively big
• ProcessStartInfo hanging on "WaitForExit"? Why?
• http://msdn.microsoft.com/en-us/library/system.diagnostics.processstartinfo.redirectstandardoutput.aspx (remarks section)