Automation for nginx and uWSGI Emperor setup. Based on my pyweb tutorial and Ansible.

Version: 2.4 — changelog

The support list matches the tutorial:

• Ubuntu 18.04 LTS, 20.04 LTS or newer
• Debian 10 (buster), 11 (bullseye) or newer
• Fedora 33 or newer (with SELinux enabled and disabled)
• CentOS 7 (with SELinux enabled and disabled)
• AlmaLinux 8 (with SELinux enabled and disabled). Referred to as “EL8” collectively with Rocky Linux.
• Rocky Linux 8 (with SELinux enabled and disabled). Referred to as “EL8” collectively with AlmaLinux.
• Arch Linux

Debian 8 (jessie), 9 (stretch), Ubuntu 16.04 LTS, and Fedora 24 through 32 are not officially supported, even though they still probably work. Other operating systems are unsupported, because of packaging and default configuration differences.

Standard Ansible Playbooks procedure. Install Ansible, edit the applicable configuration in group_vars, put hostnames in hosts (the first line is [nginx-uwsgi] and the following lines are hostnames; default is to install on localhost) and run:

$ ansible-playbook nginx-uwsgi.yml -i hosts

(You may want to add the -K option to be asked for the sudo password.)

To understand what the Playbook does, make sure to read the pyweb tutorial.

Configuration happens in three files: hosts, group_vars/all, and group_vars/os_<destination OS>.

• app_name: the application name, used for configuration files (default: myapp)

• app_package, app_callable: WSGI module to use (default: flaskapp, app)

  Framework	Flask, Bottle	Django	Pyramid
  Package	module where app is defined	project.wsgi (project is the package with settings.py)	module where app is defined
  Callable	Flask: app instance Bottle: app = bottle.default_app()	application	app = config.make_wsgi_app()
  Module	package:app	project.wsgi:application	package:app
  Caveats	Make sure app is not in an if __name__ == '__main__': block	Add environment variable for settings: env = DJANGO_SETTINGS_MODULE=project.settings	Make sure app is not in an if __name__ == '__main__': block (the demo quickstart does that!)

• base_dir: the base directory (and virtual environment) for the app (default: /srv/myapp)

• appdata_dir: the directory where app data files reside (default: {{ base_dir }}/appdata)

• nginx_server_name: hostnames the website is accessible under (default: localhost myapp.local)

• nginx_http_port: port to use when serving HTTP (default: 80)

• uwsgi_module: WSGI module to use (constructed from app_package, app_callable — leave it as-is)

• uwsgi_processes and uwsgi_threads: control the resources devoted to this application. (default: 1 and 1; should be more for bigger apps)

• uwsgi_env: list of environment variables to pass to the app (in key=value format; default: empty)

• git_repo: Git repository that contains app code (default: https://github.com/Kwpolska/flask-demo-app)

• git_branch: Git branch to pull from (default: master)

• nginx_hostless_global_config: Replace nginx.conf with one that does not have a default host. Destructive, see caveat below! (default: no)

• uid: user used for files and sockets
• gid: group used for files and sockets
• nginx_dir: nginx sites directory (conf.d or sites-enabled)
• uwsgi_dir: uWSGI vassals directory
• uwsgi_plugins: uWSGI plugins (python3,logfile or python)
• uwsgi_service_name: uWSGI systemd service name (uwsgi or emperor.uwsgi)

• nginx_patch_confd_Archlinux: patch /etc/nginx/nginx.conf to use conf.d (default: yes; may fail)
• nginx_disable_default_site: disable the default site by removing /etc/nginx/sites-enabled/default (default: yes; for Debian/Ubuntu)
• skip_selinux: skip SELinux tasks (default: no; for CentOS/EL8/Fedora)

Make sure you have the following packages installed first on the destination machine (Ansible dependencies):

• Debian/Ubuntu: python
• Fedora: python2 python2-dnf libselinux-python
• AlmaLinux, CentOS, Rocky Linux: python libselinux-python
• Arch Linux: python2

The default config of nginx creates some servers with default pages. Not everyone wants that. If you want this playbook to replace your nginx.conf file with one that has no servers (based on your OSes default nginx.conf), set nginx_hostless_global_config to yes. You should not use it if you customized /etc/nginx/nginx.conf in any way, or if you have installed and configured nginx before. On Ubuntu and Debian, nginx_disable_default_site is less destructive and enabled by default.

The nginx host config is rudimentary and does not include SSL/TLS support and custom error pages. For the former, see Remy van Elst’s guide.

By default, nginx on Arch Linux does not have any modular-include config directory. This playbook (and best practices) recommend having one for cleaner config. This playbook will try to patch your configuration file, but if you configured nginx in a way that makes the patch fail, you need to manually add this snippet to your server {} block:

# Load modular configuration files from the /etc/nginx/conf.d directory.
# See http://nginx.org/en/docs/ngx_core_module.html#include
# for more information.
include /etc/nginx/conf.d/*;

Afterwards, disable patching — set nginx_patch_confd_Archlinux to no. You should also disable this patch if you already used this playbook, or have a modular configuration directory already (you can change the path in config).

If you’re installing to a place that doesn’t like symlinks — for example, a VM shared folder (eg. /vagrant) on a Windows host, you may get a Protocol error pointing to a os.symlink call. You can fix this by amending the venv command to use --copy, or by using a more reasonable place to store your virtual environment (a Unix filesystem, that is).

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