flask running in mod_wsgi cannot write to /tmp
I think is related to this answer:https://unix.stackexchange.com/questions/167835/where-apaches-tmp-located
Apache might be using private-tmp which causes /tmp to be redirected to /var/tmp/systemd-private--httpd.service-/
Try setting the app logger level to DEBUG (and adding a Handler):
import loggingfrom logging.handlers import RotatingFileHandlerimport flaskapp = flask.Flask(__name__)@app.before_first_requestdef initstuff(): test_file = '/tmp/test' with open(test_file, 'w') as f: f.write('test')@app.route('/', methods=['GET'])def rootdir(): return 'Hello world'if __name__ == '__main__': handler = RotatingFileHandler('app.log', maxBytes=10000, backupCount=1) handler.setLevel(logging.DEBUG) app.logger.addHandler(handler) app.run(host='0.0.0.0', port=8056, debug=True, use_reloader=False)Then look in app.log to see what the problem is.