qgis-check-platform

#!/usr/bin/env python3

import os
import sys
import logging

from time import sleep

qgis_application = None


def start_qgis_application(enable_gui=False, enable_processing=False, verbose=False, cleanup=True):

    global qgis_application
    from qgis.core import QgsApplication, QgsMessageLog, QgsProviderRegistry

    # In python3 we need to convert to a bytes object (or should
    # QgsApplication accept a QString instead of const char* ?)
    try:
        argvb = list(map(os.fsencode, sys.argv))
    except AttributeError:
        argvb = sys.argv

    qgis_application = QgsApplication(argvb, enable_gui )
    qgis_application.setPrefixPath('/usr', True)
    qgis_application.initQgis()

    if cleanup:
        import atexit
        print("Installing cleanup hook")
    
        @atexit.register
        def exitQgis():
            if qgis_application:
                qgis_application.exitQgis()    

    if verbose:
        print(qgis_application.showSettings())

    # Add a hook to qgis  message log 
    def writelogmessage(message, tag, level):
        print('Qgis: {}({}): {}'.format( tag, level, message ), file=sys.stderr)

    QgsApplication.instance().messageLog().messageReceived.connect( writelogmessage )

    print("QGIS initialized......")

    if enable_processing:
        sys.path.append("/usr/share/qgis/python/plugins/")
        from processing.core.Processing import Processing
        from qgis.analysis import QgsNativeAlgorithms
        QgsApplication.processingRegistry().addProvider(QgsNativeAlgorithms())
        Processing.initialize()
        print("QGis processing initialized")


def stop_qgis_application():
    """ Cleans up and exits QGIS
    """
    global qgis_application
    
    qgis_application.exitQgis()
    del qgis_application


def print_processing_algs_tree():
    """ Print all processing providers/modules
    """
    for provider in qgis_application.processingRegistry().providers():
        if provider.isActive:
            print('* |--- ', provider.name() )
        else:
            print('  |--- ', provider.name() )
        for alg in provider.algorithms():
            print('    |---', alg.name())
    
def print_processing_algs_list():
    """ Print all processing providers/modules
    """
    for provider in qgis_application.processingRegistry().providers():
        for alg in provider.algorithms():
            print('%s/%s' % (provider.name(),alg.name()))
 

if __name__ == '__main__':

    import argparse

    parser = argparse.ArgumentParser(description='Run headless qgis app and exit')
    parser.add_argument('--verbose', action='store_true', default=False )
    parser.add_argument('--disable-exit-hook', action='store_true', default=False)
    parser.add_argument('--list-processing-algs', choices=['tree','list'], default='tree')

    args = parser.parse_args()

    #  We MUST set the QT_QPA_PLATFORM to prevent
    #  Qt trying to connect to display
    os.environ['QT_QPA_PLATFORM'] = 'offscreen'

    start_qgis_application(verbose = args.verbose, 
                           enable_processing = True,
                           cleanup = not args.disable_exit_hook)

    if args.list_processing_algs == 'tree':
        print_processing_algs_tree()
    else:
        print_processing_algs_list()