Develop Reference

How to rename Flask WSGI App during development?

I would like to know how can I change the name of the Flask WSGI App during the development stage.
Using the Flask Mega-Tutorial as reference, I was able to successfully setup a "Hello World" app.
Digressions from the tutorial:
Use pipenv as my Python virtual environment manager (instead of venv)
Name of the app is astronomer.py.
Now, I want to build on top of the existing app and customize the code to my requirements; starting with the app name that I have defined in the .flaskenv file as FLASK_APP env var.
Accordingly, I have updated the name of the root level Python script from astronomer.py (in the tutorial) to galielo.py (for my use). After changing the corresponding value of FLASK_APP and restarting the flask server via $ pipenv run flask run, the app crashes with the following error:
$ pipenv run flask run [12:29:33]
* Serving Flask app "astronomer.py" (lazy loading)
* Environment: development
* Debug mode: on
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
* Restarting with stat
* Debugger is active!
* Debugger PIN: 302-012-958
127.0.0.1 - - [09/Oct/2019 12:29:57] "GET / HTTP/1.1" 500 -
Traceback (most recent call last):
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 240, in locate_app
__import__(module_name)
ModuleNotFoundError: No module named 'astronomer'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 338, in __call__
self._flush_bg_loading_exception()
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 326, in _flush_bg_loading_exception
reraise(*exc_info)
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/_compat.py", line 39, in reraise
raise value
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 314, in _load_app
self._load_unlocked()
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 330, in _load_unlocked
self._app = rv = self.loader()
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 388, in load_app
app = locate_app(self, import_name, name)
File "/Users/kshitij10496/.local/share/virtualenvs/galileo-iQPdbs28/lib/python3.7/site-packages/flask/cli.py", line 250, in locate_app
raise NoAppException('Could not import "{name}".'.format(name=module_name))
flask.cli.NoAppException: Could not import "astronomer".
Debugging
After logging into the virtual env and checking for the value of the env var FLASK_APP, I get the old value of astronomer.py. This explains why the application is not starting. However, I'm not able to understand why this is happening?
I even tried using "eager-loading" the app using: $ pipenv run flask run --eager-loading
Still, the app does not start with the same error message ofcourse.
I was able to solve this manually by unsetting the env var FLASK_APP from within the virtual env and restarting the flask server. I'm curious to know about why the app is not loading the file .flaskenv at initialization and if there is an automated way to do this?

With Pipenv, I think things are a little bit different when it comes to environment variables. As per the documentation, there is a builtin mechanism for loading a .env file:
If a .env file is present in your project, $ pipenv shell and $ pipenv run will automatically load it, for you
So I guess you should rename your file from .flaskenv to .env and then safely remove the python-dotenv dependency.

App Engine + Django: ImportError: No module named django.core.wsgi

I'm deploying a simple Django app to Google App Engine. How can I fix the following?
Traceback (most recent call last):
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 240, in Handle
handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
handler, path, err = LoadObject(self._handler)
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 96, in LoadObject
__import__(cumulative_path)
File "/base/data/home/apps/.../20171104t152156.405293023907909181/mysite/wsgi.py", line 12, in <module>
from django.core.wsgi import get_wsgi_application
ImportError: No module named django.core.wsgi

You're getting the ImportError because Django is not in your sys.path.
If you want to use one of the built-in Django versions from the App Engine SDK, simply add this to your app.yaml (it's not necessary to install the Django library separately):
libraries:
- name: django
version: "1.4"
Update:
If you want to include your own Django version with your app (eg. to use a recent version > 1.5), don't add the above line and instead install the library directly into your project's root directory:
$ cd myapp/
$ pip install django -t .

Google App Engine: No module named google.api

I have installed the latest version of google cloud sdk, google-cloud-sdk-app-engine-python on my Ubuntu PC as mentioned in the docs in-order to test google-cloud-endpoints-framework sample app.
But on invoking an api request, I got the below traceback. Seems like there is a conflict between google package inside GAE sdk and the google package installed automatically to the lib folder because of google-endpoints package.
$ dev_appserver.py app.yaml
INFO 2017-03-14 07:51:36,173 devappserver2.py:764] Skipping SDK update check.
INFO 2017-03-14 07:51:36,199 api_server.py:268] Starting API server at: http://localhost:44561
INFO 2017-03-14 07:51:36,213 dispatcher.py:199] Starting module "default" running at: http://localhost:8080
INFO 2017-03-14 07:51:36,213 admin_server.py:116] Starting admin server at: http://localhost:8000
INFO 2017-03-14 07:51:45,811 module.py:806] default: "GET /_ah/start HTTP/1.1" 404 -
ERROR 2017-03-14 07:51:45,877 wsgi.py:263]
Traceback (most recent call last):
File "/usr/lib/google-cloud-sdk/platform/google_appengine/google/appengine/runtime/wsgi.py", line 240, in Handle
handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
File "/usr/lib/google-cloud-sdk/platform/google_appengine/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
handler, path, err = LoadObject(self._handler)
File "/usr/lib/google-cloud-sdk/platform/google_appengine/google/appengine/runtime/wsgi.py", line 85, in LoadObject
obj = __import__(path[0])
File "/home/gemini/gae projects/python-docs-samples/appengine/standard/endpoints-frameworks-v2/echo/main.py", line 19, in <module>
import endpoints
File "/home/gemini/gae projects/python-docs-samples/appengine/standard/endpoints-frameworks-v2/echo/lib/endpoints/__init__.py", line 29, in <module>
from apiserving import *
File "/home/gemini/gae projects/python-docs-samples/appengine/standard/endpoints-frameworks-v2/echo/lib/endpoints/apiserving.py", line 74, in <module>
from google.api.control import client as control_client
File "/usr/lib/google-cloud-sdk/platform/google_appengine/google/appengine/tools/devappserver2/python/sandbox.py", line 1001, in load_module
raise ImportError('No module named %s' % fullname)
ImportError: No module named google.api
I tried creating a seperate virtualenv but the problem still exists.

Here is the reply from a google guy..
Local development with endpoints framework v2 isn't currently supported, you'll need to deploy the app.
https://github.com/GoogleCloudPlatform/python-docs-samples/issues/853

Your error :
ImportError: No module named google.api
So you need first to install gcloud python module and google-api-python-client module with:
pip install --upgrade gcloud
pip install --upgrade google-api-python-client
from here

I had a similar issue with other Google packages in my lib directory.
I solved/monkey patched it using the following code in my appengine_config.py file:
import sys
import os
import google
from google.appengine.ext import vendor
lib_directory = os.path.dirname(__file__) + "<relative path to lib dir>"
google.__path__.append(os.path.join(lib_directory, 'google'))
logging.info("importing lib %s" % (lib_directory))
vendor.add(lib_directory)

Adding Google Analytics API Library to Google App Engine

I am trying to run a simple python script on Google App Engine. How do I install the Google Analytics API library?
Library: https://developers.google.com/api-client-library/python/apis/analytics/v3
Instructions: https://cloud.google.com/appengine/docs/python/tools/libraries27#vendoring
I've tried everything and can't get this to run, even though it works on my pc. What I have right now is:
The python scripts in the root folder,
In the /lib folder I copied the folders that were installed from my PC (/googleapiclient and /google_api_python_client-1.4.0-py2.7.egg-info)
And I have appengine_config.py in /lib folder which contains:
from google.appengine.ext import vendor
# Add any libraries installed in the "lib" folder.
vendor.add('lib')
vendor.add('google-api-client')
app.yaml file:
application: psyched-cab-861
version: 1
runtime: python27
api_version: 1
threadsafe: true
handlers:
- url: /.*
script: hello_analytics_api_v3.app
Traceback:
Traceback (most recent call last):
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 240, in Handle
handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 299, in _LoadHandler
handler, path, err = LoadObject(self._handler)
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 85, in LoadObject
obj = __import__(path[0])
ImportError: No module named helloworld
New Log:
Traceback (most recent call last):
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/runtime/wsgi.py", line 240, in Handle
handler = _config_handle.add_wsgi_middleware(self._LoadHandler())
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/lib_config.py", line 354, in __getattr__
self._update_configs()
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/lib_config.py", line 290, in _update_configs
self._registry.initialize()
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/api/lib_config.py", line 165, in initialize
import_func(self._modname)
File "/base/data/home/apps/s~just-terminus-94303/1.384249106864280829/appengine_config.py", line 5, in <module>
vendor.add('google-api-python-client')
File "/base/data/home/runtimes/python27/python27_lib/versions/1/google/appengine/ext/vendor/__init__.py", line 44, in add
'No such virtualenv or site directory' % path)
ValueError: virtualenv: cannot access google-api-python-client: No such virtualenv or site directory
I tried editing the appengine_config.py file to
vendor.add('googleapiclient') #The name of the file
I edit it in GAE, and click commit, it saves, but I get the same error as above with the vendor.add('google-api-python-client') error. Why is the file not updating?

As the docs say: put the appengine_config.py in your root folder of the application (and not in the /lib folder).
By the way, the name of the library is google-api-python-client and not google-api-client.
Then you have to install google-python-api-client in your /lib folder:
$ pip install -t lib google-api-python-client

ImportError: No module named config on Travis-CI build

I'm having an import error on Travis builds, the error is related to the configuration of flask:
from flask import Flask
app = Flask(__name__)
app.config.from_object('config')
On local machine, the flask app run correctly. But on travis here is the error trace
$ nosetests --with-coverage --cover-package=core
E.........................
======================================================================
ERROR: Failure: ImportStringError (import_string() failed for 'config'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
Debugged import:
- 'config' not found.
Original exception:
ImportError: No module named config)
----------------------------------------------------------------------
Traceback (most recent call last):
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/nose/loader.py", line 414, in loadTestsFromName
addr.filename, addr.module)
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/nose/importer.py", line 47, in importFromPath
return self.importFromDir(dir_path, fqname)
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/nose/importer.py", line 94, in importFromDir
mod = load_module(part_fqname, fh, filename, desc)
File "/home/travis/build/dzlab/sentimentpy/webapp/app/__init__.py", line 6, in <module>
app.config.from_object('config')
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/flask/config.py", line 162, in from_object
obj = import_string(obj)
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/werkzeug/utils.py", line 426, in import_string
sys.exc_info()[2])
File "/home/travis/virtualenv/python2.7_with_system_site_packages/local/lib/python2.7/site-packages/werkzeug/utils.py", line 408, in import_string
return __import__(import_name)
ImportStringError: import_string() failed for 'config'. Possible reasons are:
- missing __init__.py in a package;
- package or module path not included in sys.path;
- duplicated package or module name taking precedence in sys.path;
- missing module, class, function or variable;
What's wrong with my configuration?

import_string only takes absolute module imports. Since config is not a top-level module, but part of webapp, you need to specify webapp.config. See http://flask.pocoo.org/docs/0.10/config/#configuring-from-files:
app = Flask(__name__)
app.config.from_object('yourapplication.default_settings')
app.config.from_envvar('YOURAPPLICATION_SETTINGS')

I came across this issue recently and could not figure it out until I had an epiphany after 2nd days by reading Markus's answer.
Just in-case someone out there is looking for a solution to load the configuration from config.py and the flask app is using a package structure then ensure to provide the full classpath to the config class file in app.config.from_object().
For e.g., I had a configuration myproj/app/config.py in my flask project myproj and the class file with the configuration was DevelopmentConfig. You need to provide it as follows:
app.config.from_object('app.config.DevelopmentConfig')
Another example would be if you put the same file under myproj/instance/config.py then, you call it as:
app.config.from_object('instance.config.DevelopmentConfig')
During the development of your app, the easiest way to change your settings would be to put an environment variable in myapp/.env file like so:
FLASK_APP=app
APP_SETTINGS="app.config.DevelopmentConfig"
and use the variable in your app.config.from_object() call:
app.config.from_object(os.environ['APP_SETTINGS'])
But do remember that for the .env to take effect, you need to start your app with flask run instead of running the app directly.