Passenger: Flask example app
License: MIT License
This is a Flask hello world example app for the Passenger application server.
The master branch contains the code without Passenger installed.
The end_result branch contains the code with Passenger installed.
Run git diff origin/master..origin/end_result to see what's different.
/usr/share/passenger/helper-scripts/wsgi-loader.py:26: DeprecationWarning: the imp module is deprecated in favour of importlib; see the module's documentation for alternative uses
import sys, os, re, imp, threading, signal, traceback, socket, select, struct, logging, errno
Traceback (most recent call last):
File "/usr/share/passenger/helper-scripts/wsgi-loader.py", line 369, in
app_module = load_app()
File "/usr/share/passenger/helper-scripts/wsgi-loader.py", line 76, in load_app
return imp.load_source('passenger_wsgi', startup_file)
File "/usr/lib/python3.9/imp.py", line 171, in load_source
module = _load(spec)
File "", line 711, in _load
File "", line 680, in _load_unlocked
File "", line 855, in exec_module
File "", line 228, in _call_with_frames_removed
File "/var/www/power_flask/powerhome_flask/passenger_wsgi.py", line 1, in
from app import app as application
File "/var/www/power_flask/powerhome_flask/app/init.py", line 3, in
from flask import Flask
ModuleNotFoundError: No module named 'flask'
Question 1: What is the problem?:
I want to install Nginx and Passenger on Ubuntu 16.04 to run python apps e.g. using Flask and I run into issues. When I visit my server http://hXXXXXXX.stratoserver.net/ in the browser I am getting:
We're sorry, but something went wrong.
Question 2: Passenger version and integration mode:
Passenger open source 6.0.4 + Nginx
Question 3: OS or Linux distro, platform (including version):
Ubuntu 16.04 LTS
$ uname -a
Linux hXXXXXXX.stratoserver.net 4.4.0-042stab141.3 phusion/passenger#1 SMP Fri Nov 15 22:45:34 MSK 2019 x86_64 x86_64 x86_64 GNU/Linux
$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description: Ubuntu 16.04.6 LTS
Release: 16.04
Codename: xenial
Question 4: Passenger installation method:
Nginx + Phusion APT repo
Question 5: Your app's programming language (including any version managers) and framework (including versions):
Python 3.7.6 + Flask 1.1.1
Question 6: Are you using a PaaS and/or containerization? If so which one?
NA
Question 7: Anything else about your setup that we should know?
I have a VPS at strato.nl with Ubuntu 16.04 installed, and the host address is: http://hXXXXXXX.stratoserver.net/ and I was following "Deploying a Python app with Passenger to production" tutorial with the following infrastructure:
Linux/Unix
Nginx
Passenger open source
Python installed via LinuxBrew
Passenger installed on Ubuntu 16.04 LTS
Demo Flask app from github
So the demo Flask app was cloned like this:
git clone https://github.com/phusion/passenger-python-flask-demo.git
Running passenger-memory-stats gives:
$ sudo /usr/sbin/passenger-memory-stats
Version: 6.0.4
Date : 2020-01-29 13:12:15 +0100
------------- Apache processes -------------
*** WARNING: The Apache executable cannot be found.
Please set the APXS2 environment variable to your 'apxs2' executable's filename, or set the HTTPD environment variable to your 'httpd' or 'apache2' executable's filename.
---------- Nginx processes -----------
PID PPID VMSize Private Name
--------------------------------------
23320 1 174.9 MB 0.8 MB nginx: master process /usr/sbin/nginx -g daemon on; master_process on;
23325 23320 174.9 MB 0.8 MB nginx: worker process
### Processes: 2
### Total private dirty RSS: 1.54 MB
----- Passenger processes -----
PID VMSize Private Name
-------------------------------
23309 445.7 MB 2.5 MB Passenger watchdog
23312 672.3 MB 7.5 MB Passenger core
### Processes: 2
### Total private dirty RSS: 9.98 MB
When I run the app locally on the server everything works as expected:
$ python app.py
* Serving Flask app "app" (lazy loading)
* Environment: production
WARNING: This is a development server. Do not use it in a production deployment.
Use a production WSGI server instead.
* Debug mode: off
* Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
Then in another terminal:
$ curl localhost:5000
<!DOCTYPE html>
<html>
<head>
<title>Hello</title>
<style>
html, body {
font-family: sans-serif;
background: #f0f0f0;
margin: 4em;
}
.main {
background: white;
border: solid 1px #c0c0c0;
border-radius: 8px;
padding: 2em;
}
</style>
</head>
<body>
<section class="main">
<h1>Hello world!</h1>
<p>Welcome to the Passenger Flask example app.</p>
</section>
</body>
</html>
So it looks like locally all works fine.
However when I visit http://hXXXXXXX.stratoserver.net/ in the browser I got an error page like described above.
The nginx error /var/log/nginx/error.log:
App 29730 output: Traceback (most recent call last):
App 29730 output: File "/usr/share/passenger/helper-scripts/wsgi-loader.py", line 369, in <module>
App 29730 output:
App 29730 output: app_module = load_app()
App 29730 output: File "/usr/share/passenger/helper-scripts/wsgi-loader.py", line 76, in load_app
App 29730 output:
App 29730 output: return imp.load_source('passenger_wsgi', startup_file)
App 29730 output: File "/var/www/demoapp/code/passenger_wsgi.py", line 3, in <module>
App 29730 output:
App 29730 output: from app import MyApp as application
App 29730 output: File "/var/www/demoapp/code/app.py", line 1, in <module>
App 29730 output:
App 29730 output: from flask import Flask, render_template
App 29730 output: ImportError
App 29730 output: :
App 29730 output: No module named flask
It seems the server uses Python2 by default.
I need it to use Python3 where I installed Flask.
How can I setup the Python version and Python libraries in Nginx/Passenger?
My demoapp.conf is:
$ vi /etc/nginx/sites-enabled/demoapp.conf
server {
listen 80;
server_name hXXXXXXX.stratoserver.net;
# Tell Nginx and Passenger where your app's 'public' directory is
root /var/www/demoapp/code/public;
# Turn on Passenger
passenger_enabled on;
passenger_app_env development;
passenger_friendly_error_pages off;
passenger_user demoapp;
}
What are the passenger / Nginx settings that I need to set to successfully run a Flask application?
How can I set Passenger/Nginx to use Python3 and Python3 libraries?
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