Django makes it so easy to get started; ``manage.py runserver`` and away you go. But deploying an application so that the system can provide redundancy and scalability requires some heavier lifting: package installs, configuration settings, multiple servers, security, backups, etc. Ansible is a python-based configuration management tool which helps automate and repeat deployments whether the hardware is local or in the cloud. We'll be covering how to leverage existing configurations, write your own and sharing best practices for deploying django applications.

1. copyright
2014.
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rights
reserved.
Deploying Django with Ansible
Andrew
Mirsky

2. copyright
2014.
all
rights
reserved.
For
development:
~/myproject > ./manage.py runserver
Validating models...
0 errors found
May 30, 2014 - 11:31:08
Django version 1.6.2, using settings 'settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.
For
produc0on:
/var/www > sudo ./manage.py runserver 0.0.0.0:80 /dev/null 2>&1 &
/var/www >
running a django server

3. copyright
2014.
all
rights
reserved.
production setup
• One
or
more
applica=ons
(aka
virtual
servers)
• Mul=ple
applica=on
processes
&
monitoring
• Data
storage
&
retrieval
(aka
databases)
• Security
• Maintainable,
robust,
scalable

4. copyright
2014.
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rights
reserved.
basic setup

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2014.
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rights
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components
• webservers
– apache
– nginx
– cherokee
• interpreter
– mod_wsgi
– uwsgi
– gunicorn
• databases
– postgres
– mysql
– [
mongodb,
couchdb,
cassandra
]

6. copyright
2014.
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rights
reserved.
scalable setup

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2014.
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rights
reserved.
scalable, redundant setup

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2014.
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rights
reserved.
ansible

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2014.
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rights
reserved.
ansible for single commands
> pip install ansible
> ansible webservers –i myinventory -a ”touch /srv/foo.txt && /sbin/reboot" -f 10

10. copyright
2014.
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rights
reserved.
anatomy of an inventory
> cat inventory
# file: inventory
[webservers]
app[0:4].mirsky.net ansible_ssh_private_key_file=~/.ssh/key1.pem
[dbservers]
db[0:2].mirsky.net ansible_ssh_private_key_file=~/.ssh/key2.pem
[mytotalsite:children]
webserver
dbservers

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2014.
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rights
reserved.
ansible playbooks

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2014.
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rights
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building playbooks
> pip install ansible-role-manager
> arm help
usage: /Users/andrew/env/arm/bin/arm [-h] {freeze,help,init,install,uninstall} ...
positional arguments: {freeze,help,init,install,uninstall}
freeze produces dependencies file for this playbook based on...
help an alias for calling `-h` on any subcommand
init initialize directory structure & files
install install playbook role
uninstall remove a role from the library of dependencies
> arm init -p mydjangoplaybook
ansible playbook created successfully
> arm install git+https://github.com/mirskytech-ansible/role-postgres.git

13. copyright
2014.
all
rights
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anatomy of a playbook
> cat mydjangoplaybook/mysite.yml
## file: mysite.yml !!
!!
## usage: ansible-playbook -i <inventory file> mysite.yml !!
- hosts: webservers
vars: webservers
- project: mydjangoproject
roles:
- cherokee
- postgres
tasks:
- name: install uwsgi & postgres modules
sudo: yes
pip: name="uwsgi psycopg2”

14. copyright
2014.
all
rights
reserved.
anatomy of a role
> cat roles/cherokee/tasks/main.yml
---
## file: cherokee/tasks/main.yml
- name: add cherokee ppa
sudo: yes
command: mkdir /srv/www && chgrp www-data /srv/www
- name: add cherokee ppa
sudo: yes
apt_repository: repo="ppa:cherokee-webserver" state="present"
register: ppa_add
ignore_errors: true
- name: package install
sudo: yes
apt: pkg={{ item }} state=present update_cache=yes
with_items:
- cherokee
- libcherokee-mod-libssl
register: apt_install
ignore_errors: true
when: ppa_add|success

15. copyright
2014.
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rights
reserved.
anatomy of a task
- name: create uwsgi config file
sudo: yes
template: >
src=templates/uwsgi.ini.j2
dest=/srv/www/{{ project }}/uwsgi.ini
group='www-data'
mode=660
register: this_task_rc
ignore_errors: true
when: previous_task_rc|success
> cat templates/uwsgi.ini.j2
# uwsgi.ini for {{ hostname }}
[uwsgi]
vhost = true
master = true
enable-threads = true
processes = 2
wsgi-file = /srv/www/{{ project }}/webapp/wsgi.py
virtualenv = /srv/env/{{ project }}
chdir = /srv/www/{{ project }}
touch-reload = /srv/reload/{{ project }}
pythonpath = /srv/www/{{ project }}
daemonize = /var/log/{{ hostname }}.log
post-buffering = 32768 Ansible’s
Template
Module
Docs

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2014.
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rights
reserved.
anatomy of a module
> cat library/mymodule_command
from ansible.module_utils.basic import *
def main():
# module arguments
module_args = dict( username = dict(required=True) )
# module instantiation
module = AnsibleModule( argument_spec = module_args, supports_check_mode=True,)
# module variables
username = module.params[’username']
# module execution
# do something
# if something fails:
# module.fail_json(msg=‘command failed’)
module_returns = {
"result":"my module’s result was blah",
"changed" : False,
"rc" : 4,
"ansible_facts" : {},
}
module.exit_json(**module_returns)
main()

17. copyright
2014.
all
rights
reserved.
resources
• Ansible
Role
Manager
hNps://pypi.python.org/pypi/ansible-­‐role-­‐manager
• Django
Deploy
&
Release
Playbooks
hNps://github.com/mirskytech-­‐ansible/playbook-­‐django
• Ansible
Tower
• Ansible
Galaxy
• Ansible
Docs
hNp://docs.ansible.com/quickstart.html
hNp://docs.ansible.com/playbooks_best_prac=ces.html
hNp://docs.ansible.com/list_of_all_modules.html
hNp://docs.ansible.com/
• MirskyTech
Blog
hNp://mirskytech.com/overflow/
• Django
Pony
Logo
hNp://doctormo.deviantart.com/art/Django-­‐Python-­‐Pony-­‐449031453
contact info
questions?
andrew@mirskytech.com