from flask import Flask app = Flask(__name__) @app.route('/crash') def main(): raise Exception() # bad app.run(debug=True) app.run('host', 8080, True) # okay app.run() app.run(debug=False) # also okay run(debug=True) app.notrun(debug=True) # a slightly more involved example using flow and truthy values DEBUG = True app.run(debug=DEBUG) # NOT OK DEBUG = 1 app.run(debug=DEBUG) # NOT OK if False: app.run(debug=True) runapp = app.run runapp(debug=True) # NOT OK # imports from other module import settings app.run(debug=settings.ALWAYS_TRUE) # NOT OK # depending on environment values import os DEPENDS_ON_ENV = os.environ["ENV"] == "dev" app.run(debug=DEPENDS_ON_ENV) # OK