Create a Self-Updating Python Desktop App: Detect, Download, and Replace

Desktop GUI Options

Python provides several libraries for creating cross‑platform desktop graphical user interfaces, including the built‑in Tkinter, the powerful PyQt5 and PySide2, as well as wxPython. These modules enable developers to write GUI programs that run on Windows, macOS, and Linux.

Packaging Tools

To distribute a desktop application, third‑party packaging tools such as PyInstaller, Nuitka, and cx_Freeze can bundle the Python code and its dependencies into a single executable file (e.g., a Windows .exe) or a folder containing all required files.

Why an Update Mechanism Is Needed

Unlike web applications, desktop programs are distributed offline. When a new version is released, the developer must re‑package the program, host the new executable, and ask users to download and install the update manually. Without a proper update flow, users may continue using outdated software.

Update Detection

The application should query a remote update server at startup (usually in a background thread) to determine whether a newer version is available.

Downloading Updates

If an update exists, the program can download it in two ways: directly from the main application or by invoking a separate updater program. The latter is preferred because it allows the updater to replace the running executable.

Download using the main program (cannot overwrite itself).

Launch a dedicated updater executable that handles the download and replacement.

The updater can fetch the update package with the requests library. Example code:

def work(self):
    # Create a temporary file for the update package
    temp_file = os.path.join(self.download_path, 'update.zip')
    logger.info("Download temporary file path: {}".format(temp_file))
    with open(temp_file, 'wb') as self.fileobj:
        # Stream the update file from the server
        f = requests.get(self.download_url, stream=True)
        offset = 0
        for chunk in f.iter_content(chunk_size=self.buffer):
            if not chunk:
                break
            self.fileobj.seek(offset)
            self.fileobj.write(chunk)
            offset += len(chunk)
            progress = offset / int(self.filesize) * 100
            self.download_proess_signal.emit(int(progress))

Extracting and Replacing Files

After the new version is downloaded, the updater terminates the running main process, extracts the update archive into the original installation directory, and cleans up temporary files.

def work(self):
    # 1. Kill the main application process
    for proc in psutil.process_iter():
        if proc.name() == 'xxx.exe':
            proc.kill()
    # 2. Get the current program path
    current_path = os.path.dirname(os.path.abspath(__file__))
    logger.info("Current program path: {}".format(current_path))
    # 3. Extract the update zip to the program directory
    update_file_path = os.path.join(self.download_temp_path, 'update.zip')
    shutil.unpack_archive(filename=update_file_path, extract_dir=current_path)
    # 4. Remove temporary files
    os.remove(update_file_path)
    shutil.rmtree(self.download_temp_path)

By following these steps, a Python‑based desktop GUI application can automatically detect updates, download the new version, and replace the old files without requiring manual user intervention.