[PYTHON] Try running a Django application on an nginx unit

Introduction

This article is JSL (Japan System Giken) Advent Calendar 2020 --Qiita 24th day article.

In the Advent Calendar Article the other day, I wrote about nginx unit, which I was more interested in than before because I had achieved the quota once a year but wanted to challenge the record.

What is nginx unit?

Roughly speaking, it has the following features (Official page).

• NGINX application server.
• Multilingual application server.
  • Go、Node.js、Perl、PHP、Python、Ruby
• Can coexist in different language versions
• Settings can be changed without stopping the server via REST API.

This goal

• Write up to installing nginx unit on EC2 (Amazon Linux2) and deploying the Django application.

Do not write

• General preferences for Django applications
• Comparison with uWSGI and Gunicorn

Various versions

• Amazon Linux2
• Python 3.7.9
• Django 3.1.1
• MariaDB 15.1
• Nginx Unit 1.21.0

Installation

Proceed while checking the Official Page.

Create /etc/yum.repos.d/unit.repo and add the repository.

[unit]
name=unit repo
baseurl=https://packages.nginx.org/unit/amzn2/$releasever/$basearch/
gpgcheck=0
enabled=1

#installation of nginx unit
$ sudo yum install unit 

#Install the required modules
$ sudo yum install unit-devel unit-python37

#Auto start settings
$ sudo systemctl enable unit

#Start nginx unit
$ sudo systemctl start unit

#You can check the default value of each setting with the help option.
$ unitd --help 

unit options:

  --version            print unit version and configure options

  --no-daemon          run unit in non-daemon mode

  --control ADDRESS    set address of control API socket
                       default: "unix:/var/run/unit/control.sock"

  --pid FILE           set pid filename
                       default: "/var/run/unit/unit.pid"

  --log FILE           set log filename
                       default: "/var/log/unit/unit.log"

  --modules DIRECTORY  set modules directory name
                       default: "/usr/lib64/unit/modules"

  --state DIRECTORY    set state directory name
                       default: "/var/lib/unit"

  --tmp DIRECTORY      set tmp directory name
                       default: "/var/tmp"

  --user USER          set non-privileged processes to run as specified user
                       default: "nobody"

  --group GROUP        set non-privileged processes to run as specified group
                       default: user's primary group

Checking the environment

nginx unit checks and configures the environment via REST API.

$ sudo curl --unix-socket /var/run/unit/control.sock http://localhost/
{
	"certificates": {},
	"config": {
		"listeners": {},
		"applications": {}
	}
}

Currently, nothing is set.

Deploy a Django application

Deploy your Django application as well, following the official page (http://unit.nginx.org/howto/django/). Create a setting file (config.json) assuming that the deployment destination is under / var/www. I was worried about the storage location of config.json, but this time I put it under the Django application.

config.json

{
    "listeners": {
        "*:80": {
            "pass": "routes"
        }
    },
    "routes": [
        {
            "match": {
                "uri": "/static/*"
            },

            "action": {
                "share": "/var/www/my_djangoapp/"
            }
        },
        {
            "action": {
                "pass": "applications/django"
            }
        }
    ],
    "applications": {
        "django": {
            "type": "python 3.7",
            "user": "ec2-user",
            "group": "ec2-user",
            "path": "/var/www/my_djangoapp/",
            "home": "/var/www/my_djangoapp/env/",
            "module": "my_djangoapp.wsgi",
        }
    }
}

Apply config.json as follows.

$ sudo curl -X PUT --data-binary @config.json --unix-socket /var/run/unit/control.sock http://localhost/config/
{
	"success": "Reconfiguration done."
}

This completes the nginx unit settings. It becomes a Django application migrate, and it is necessary to prepare the environment by doing collect static.

Setting points

• The name specified by type in config.json specifies the module name of the directory specified by --modules, but it seems that * blank * must be inserted between the versions.

• The Django application directory must be properly owned with the values ​​specified in user and group in config.json.

Impressions

• When operating a Web application that handles multiple languages ​​and versions with microservices, I thought that it might be considered as one of the options because it seems that maintenance and operation can be performed only with nginx unit.

• The setting via REST API was fresh, but I couldn't find the syntax check function in the scope of investigation, and it was a little strict to check the error while checking the log file.

• If you are assuming a Python-only web application, I thought that uWSGI or Gunicorn would be sufficient.