Flask Traditional Deployments: Zero to One <Flask Server>

The following article will introduce how to set up your first flask server after logging in your server, and some basic linux, git commands.

[2021/08 更新] 这篇教程于 3 年前所写，大部分内容已没有参考意义，但值得一提的是，这记录了作者开发第一版博客时的心路历程 ^^

Background

• A quite developed web project ( For Flask case, flask run listens 127.0.0.1:5000 by default. However, flask run --host 0.0.0.0 listens a.b.c.d:5000 under the same wifi. Have fun with it first, then come and playing with VPS! )
• This series is a supplyment for Tradition Deploments in Chapter 17. Deployment in Flask Web Development, 2nd Edition written by Miguel Grinberg.

0. First Impression on Ubuntu

Cong! You successfully login your virtual system.

But just after that, following warning is expected to pop up:

WARNING! Your environment specifies an invalid locale.
The unknown environment variables are:
LC_CTYPE=UTF-8 LC_ALL=
This can affect your user experience significantly, including the
ability to manage packages. You may install the locales by running:
sudo apt-get install language-pack-UTF-8
​ or
sudo locale-gen UTF-8
To see all available language packs, run:
apt-cache search “^language-pack-[a-z][a-z]$”
To disable this message for all users, run:
sudo touch /var/lib/cloud/instance/locale-check.skip

Solution:

$ export LC_ALL="en_US.UTF-8"
$ export LC_CTYPE="en_US.UTF-8"
$ sudo dpkg-reconfigure locales

Please do it, or you might encounter some weird issues below, like reporting

The virtual environment was not created successfully because ensurepip is not
available. On Debian/Ubuntu systems, you need to install the python3-venv
package using the following command.

even though you might have already install python3-venv.

Now try some commands like:

• ls : list directory contents

• pwd : return working directory name

• man ls : used to see ls manual pages

• cd : change current directory

• mkdir : make directories

• rm : remove directory entries (be very very careful here)

  Tips: we can press Tab to automatically fillup the file name.

1. Pull Your Project Down to Your Server

$ cd ~  # To my main directory 
$ mkdir flask  # to make a folder for my project 
$ cd flask/ 
$ sudo apt-get install python3-venv 

Issue: you might fail to install, reporting:

E: Package ‘python3-venv’ has no installation candidate

Solution:
$ sudo apt-get update
Then install it again!

$ sudo apt-get install python3-pip 
$ git clone https://github.com/v1siuol/v1siuol-site.git 
$ cd v1siuol-site/ 
$ python3 -m venv venv 
$ pip install --upgrade pip
$ source venv/bin/activate
(venv)$ pip install -r requirements.txt 
(venv)$ mv templates.env .env 
(venv)$ vim .env  # Complete the config 
(venv)$ deactivate  # Exit the venv

Now the flask project is almost ready to go. But one more thing left behind: Setup the database.

2. MySQL on Ubuntu

$ sudo apt-get update
$ sudo apt-get install mysql-server
$ mysql_secure_installation

You need to do some selections in the last step and MySQL should be installed successfully in your server. Check by:

$ systemctl status mysql.service

● mysql.service - MySQL Community Server
Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
Active: active (running) since Tue 2018-08-14 07:01:00 UTC; 8min ago
Main PID: 15973 (mysqld)
CGroup: /system.slice/mysql.service
​ └─15973 /usr/sbin/mysqld
Aug 14 07:00:59 ip-172-31-16-238 systemd[1]: Starting MySQL Community Server…
Aug 14 07:01:00 ip-172-31-16-238 systemd[1]: Started MySQL Community Server.

Next, we will create the database for my flask project.

$ mysql -u root -p  # Enter the password you set a few minutes ago

Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.7.23-0ubuntu0.16.04.1 (Ubuntu)
Copyright © 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type ‘help;’ or ‘\h’ for help. Type ‘\c’ to clear the current input statement.

(mysql) > SHOW databases;
(mysql) > CREATE database IF NOT EXISTS v1siuol_site DEFAULT CHARSET utf8;
(mysql) > QUIT;

3. Do something Fun

(venv)$ flask run

Traceback (most recent call last):
File “/home/ubuntu/flask/v1siuol-site/venv/bin/flask”, line 11, in
​ sys.exit(main())
File “/home/ubuntu/flask/v1siuol-site/venv/lib/python3.5/site-packages/flask/cli.py”, line 894, in main
​ cli.main(args=args, prog_name=name)
File “/home/ubuntu/flask/v1siuol-site/venv/lib/python3.5/site-packages/flask/cli.py”, line 557, in main
​ return super(FlaskGroup, self).main(*args, **kwargs)
File “/home/ubuntu/flask/v1siuol-site/venv/lib/python3.5/site-packages/click/core.py”, line 676, in main
​ _verify_python3_env()
File “/home/ubuntu/flask/v1siuol-site/venv/lib/python3.5/site-packages/click/_unicodefun.py”, line 118, in _verify_python3_env
​ ‘for mitigation steps.’ + extra)
RuntimeError: Click will abort further execution because Python 3 was configured to use ASCII as encoding for the environment. Consult http://click.pocoo.org/python3/for mitigation steps.
This system supports the C.UTF-8 locale which is recommended.
You might be able to resolve your issue by exporting the
following environment variables:
export LC_ALL=C.UTF-8
export LANG=C.UTF-8
Click discovered that you exported a UTF-8 locale
but the locale system could not pick up from it because
it does not exist. The exported locale is “en_US.UTF-8” but it
is not supported

Sign :( So we add export LC_ALL=C.UTF-8 export LANG=C.UTF-8 to .env .

(venv)$ flask deploy
(venv)$ flask run --host 0.0.0.0

• Serving Flask app “v1siuol.py”
• Environment: production
  WARNING: Do not use the development server in a production environment.
  Use a production WSGI server instead.
• Debug mode: off
• Running on http://0.0.0.0:5000/ (Press CTRL+C to quit)

NOW turn up your brower, type your <public IP>:5000 as url.

<public IP> can be found in your console:

WOW!!

Thank you.