Create a web application execution environment of Python3.4 + Nginx + uWSGI + Flask with haste using venv on Ubuntu 14.04 LTS

Create a Python3.4 + Nginx + uWSGI + Flask Web application execution environment with haste using pyenv on Ubuntu 12.04 http://qiita.com/5t111111/items/e170fead91261621b054

In this 14.04 version, pyenv dependency is stopped and only venv is used.

Character

――I An ordinary high school student who attends a private high school that was a girls' school until last year. I hate humans. It will not appear after this.

• Ubuntu
  It seems to be Linux, but I'm not familiar with it.
• venv
  The one that switches the Python execution environment. It seems that it comes as standard, but I'm not familiar with it.
• Nginx
  It seems to be a web server, but I'm not familiar with it.
• uWSGI
  It seems to be a WSGI server, but I don't know what it is. I don't know WSGI in the first place.
• Flask
  It seems to be a lightweight framework that makes it easy to create web applications, but I'm not familiar with it.

Nginx installation

Added Nginx stable repository

$ sudo add-apt-repository ppa:nginx/stable

Usual update / upgrade

$ sudo apt-get update
$ sudo apt-get upgrade

Install and launch Nginx

$ sudo apt-get install nginx
$ sudo /etc/init.d/nginx start

Connect with your browser and check that the Nginx greetings page is displayed.

building flask sample application

Create application directory

Create an application directory. All application related files, including the venv virtual environment, are stored in this.

$ sudo mkdir -p /var/www/demoapp

If the user authority remains root, change it to the user you are using

$ sudo chown -R username:username /var/www/demoapp/

Creating a venv for a sample application

Unfortunately, it seems that creating venv with Python 3.4 doesn't work right now. http://qiita.com/5t111111/items/1643ba04104e75589ad4

So you need to create venv with the --without-pip option and then manually install pip.

$ pyvenv-3.4 --without-pip /var/www/demoapp/venv
$ source /var/www/demoapp/venv/bin/activate
$ mkdir ~/src
$ cd ~/src
$ curl -O https://pypi.python.org/packages/source/s/setuptools/setuptools-3.4.4.tar.gz
$ tar xvfz setuptools-3.4.4.tar.gz
$ cd setuptools-3.4.4/
$ python setup.py install
$ cd ..
$ curl -O https://pypi.python.org/packages/source/p/pip/pip-1.5.4.tar.gz
$ tar xvfz pip-1.5.4.tar.gz
$ cd pip-1.5.4/
$ python setup.py install

Flask installation

Enable venv

$ source /var/www/demoapp/venv/bin/activate

Flask installation

$ pip install flask

Creating a Flask application

Create /var/www/demoapp/hello.py.

from flask import Flask
app = Flask(__name__)

@app.route("/")
def hello():
    return "Hello World!"

if __name__ == "__main__":
    app.run(host='0.0.0.0', port=8080)

Flask application launch test

With venv enabled.

$ python /var/www/demoapp/hello.py

Check by connecting to server port: 8080 with a web browser.

Nginx settings

Removed default site settings (symlinks)

$ sudo rm /etc/nginx/sites-enabled/default

Create a configuration file for the sample application

Create /var/www/demoapp/demoapp_nginx.conf

server {
    listen      80;
    server_name localhost;
    charset     utf-8;
    client_max_body_size 75M;

    location / { try_files $uri @yourapplication; }
    location @yourapplication {
        include uwsgi_params;
        uwsgi_pass unix:/var/www/demoapp/demoapp_uwsgi.sock;
    }
}

The uWSGI server communicates with the web server Nginx via UNIX sockets or TCP. The above settings specify communication on UNIX sockets. uwsgi_pass unix:/var/www/demoapp/demoapp_uwsgi.sock;

Put a symbolic link in the Nginx config file directory

$ sudo ln -s /var/www/demoapp/demoapp_nginx.conf /etc/nginx/sites-enabled/

Nginx restart

$ sudo /etc/init.d/nginx restart

Connect to the server with a web browser and check. ** At this point, the uWSGI server is not started, so you should get a "502 Bad Gateway" error like this. ** **

uWSGI installation

Building a venv environment for uWSGI

uWSGI can also be installed from apt, but since the version is a little old, install the latest one with pip.

I think that uWSGI will be shared by multiple applications in the future, so I will prepare it separately instead of installing it in venv for the application, but since I do not want to play with the Python environment of the system, here again uWSGI with venv under / opt Create an environment for.

If you have enabled demoapp venv for your application, deactivate it.

$ deactivate

Installation of packages required to build uWSGI

You will need the following, so install it.

--C compiler --Python3 header

$ sudo apt-get install build-essential python3-dev

Create venv for uWSGI

Since it is created under / opt, work is done as root, but if you are concerned, you can change another location or authority. In that case, it is necessary to modify the path of uWSGI binary with the following settings.

As with the venv for the application, the usual method doesn't work, so install pip manually. (Troublesome ...) The following describes the procedure assuming that the source when creating venv for the application remains.

$ sudo -s
# pyvenv-3.4 --without-pip /opt/venv/uwsgi
# source /opt/venv/uwsgi/bin/activate
# cd ~/src
# cd setuptools-3.4.4/
# python setup.py install
# cd ..
# cd pip-1.5.4/
# python setup.py install

uWSGI installation

$ source /opt/venv/uwsgi/bin/activate
$ pip install uwsgi

uWSGI settings

Create a uWSGI configuration file for your application

Create /var/www/demoapp/demoapp_uwsgi.ini

[uwsgi]
#application's base folder
base = /var/www/demoapp

#python module to import
app = hello
module = %(app)

#virtualenv folder
virtualenv = /var/www/demoapp/venv

pythonpath = %(base)

#socket file's location
socket = /var/www/demoapp/%n.sock

#permissions for the socket file
chmod-socket    = 666

#the variable that holds a flask application inside the module imported at line #6
callable = app

#location of log files
logto = /var/log/uwsgi/%n.log

Creating a log output destination directory

$ sudo mkdir -p /var/log/uwsgi
$ sudo chown -R username:username /var/log/uwsgi

Start uWSGI

$ uwsgi --ini /var/www/demoapp/demoapp_uwsgi.ini

Connect to the server with a web browser and check. If Nginx and uWSGI are able to communicate with the socket without any problem, Hello World! Is displayed.

uWSGI Emperor

uWSGI Emperor is a function that reads the uWSGI configuration file and starts the uWSGI process. Multiple settings can be read and process startup can be managed collectively.

Creating an Upstart file

Create /etc/init/uwsgi.conf

description "uWSGI"
start on runlevel [2345]
stop on runlevel [06]
respawn

env UWSGI=/opt/venv/uwsgi/bin/uwsgi
env LOGTO=/var/log/uwsgi/emperor.log

exec $UWSGI --master --emperor /etc/uwsgi/vassals --die-on-term --uid www-data --gid www-data --logto $LOGTO

The last line above means to look for the config file that exists in / etc / uwsgi / vassals and start the uWSGI daemon, so Create a symbolic link to the uWSGI configuration file of the sample application in / etc / uwsgi / vassals.

$ sudo mkdir -p /etc/uwsgi/vassals
$ sudo ln -s /var/www/demoapp/demoapp_uwsgi.ini /etc/uwsgi/vassals

Permission settings

The uWSGI daemon is set to start as the www-data user. Therefore, keep the application and log directories owned as www-data.

$ sudo chown -R www-data:www-data /var/www/demoapp/
$ sudo chown -R www-data:www-data /var/log/uwsgi/

Since Nginx and uWSGI work with the same www-data user, change the socket permission to 644.

Edit /var/www/demoapp/demoapp_uwsgi.ini

...
#permissions for the socket file
chmod-socket = 644

Start uWSGI

$ sudo start uwsgi

Connect to the server with a web browser and check. If everything is fine so far, Hello World! Will be displayed.

At the end

Now that you can run your Flask application. I think there are various points to be aware of. Especially around Nginx and uWSGI, please squeeze the settings in each document and google.

reference

http://vladikk.com/2013/09/12/serving-flask-with-nginx-on-ubuntu/