Using initQgis() on headless installation of QGIS 3?

Question

When running PyQGIS testing 2.99 the following coredumps:

from qgis.core import *
QgsApplication.setPrefixPath("/usr", False)
qgs = QgsApplication([], False)
qgs.initQgis()

How to start migrating PyQGIS scripts to the upcoming QGIS 3?

Answer 1

See http://doc.qt.io/qt-5/embedded-linux.html :

Since the Qt 5.0 release, Qt no longer contains its own window system (QWS) implementation.

One solution (apart from e.g. setting the DISPLAY environment variable to some X-over-ssh value) is:

export  QT_QPA_PLATFORM=offscreen

The programmatical way in Python is:

import os
from qgis.core import *
os.environ["QT_QPA_PLATFORM"] = "offscreen"
QgsApplication.setPrefixPath("/usr", False)
qgs = QgsApplication([], False)
qgs.initQgis()