Ansible- Tower

Ansible – Tower

Ansible Tower is web-based edition of Terminal based Ansible. Below are its features

Ansible Tower – Jenkins Configure

https://www.ansible.com/blog/ansible-tower-jenkins-in-under-5-minutes

Ansible – Lab

Our company have complex multitier applications. Each of these applications contains many servers, like - load balancers(LB), web servers(WWW), database servers(DB), caching applications, and middleware queues etc.

Example policies and the sequence in which those are to be applied is shown in the following steps:

1.Database servers(DB)

Install & configure MySQL

2.Web Servers(WWW)

Install & configure Nginx with PHP bindings.
Deploy a WordPress application in Webservers and add respective configurations to Nginx.

3.Load Balancers(LB)

Install & configure HaProxy service on the load balancer hosts
Update haproxy configurations with the hostnames of all the web servers created earlier.

The following is a sample playbook that translates the infrastructure blueprint into policies enforceable by Ansible.

Task 1: Create a user, install htop & nginx on all hosts.

Create a ‘devops’ user under ‘DevOps’ group on all hosts.
Install the “htop” utility(upgrade alternative to top command).
Install Nginx on all web servers and start it as a service.

# p3_ngnix_usergroup.yml
---
- hosts: all
  remote_user: vagrant
  become: yes
  become_method: sudo
  tasks:
  - name: create devops group
    group: name=devops state=present
  - name: create devops user with admin previleges
    user: name=devops comment="Devops User" uid=2001 group=devops
  - name: install htop package
    action: apt name=htop state=present update_cache=yes

- hosts: web
  user: vagrant
  become: yes
  become_method: sudo
  tasks:
    - name: Install nginx with latest version
      apt: name=nginx state=present update_cache=true force=yes
    - name: start nginx
      service:
          name: nginx
          state: started
          
          

# inventory1_lb

[all]
web1 ansible_ssh_host=web1.satyacodes.vm ansible_user=vagrant
web2 ansible_ssh_host=web2.satyacodes.vm ansible_user=vagrant
db1 ansible_ssh_host=db1.satyacodes.vm ansible_user=vagrant
db2 ansible_ssh_host=db2.satyacodes.vm ansible_user=vagrant
lb  ansible_ssh_host=lb.satyacodes.vm ansible_user=vagrant

[web]
web1
web2

[db]
db1
db2

[backup]
db2

[lbs]
lb

Run Playbook

ansible-playbook -i inventory_lb p3_ngnix_usergroup.yml

Task 2 – WordPress Install

Step 1 — Installing Ansible

In this section we’ll install Ansible on your build-server. SSH into your build-server and run this command to install Ansible:

sudo apt-get install ansible -y

You can make sure that Ansible is installed by running:

ansible --version

Step 2 - Create Roles

Create a directory for our playbook.

mkdir wordpress

Create two files: playbook.yml, hosts

touch playbook.yml
touch hosts

split our playbooks up into roles. For this project we’ll create four roles.

server
php
mysql
wordpress

From the project root folder (~/wordpress), create a directory called roles and cd into it: mkdir roles && cd roles

we will create above roles inside roles directory(/home/vagrant/Ansible/wordpress/roles). For each role that we want to create, we will run ansible-galaxy init:

ansible-galaxy init server
ansible-galaxy init php
ansible-galaxy init mysql
ansible-galaxy init wordpress

At this point we should have the following file structure:

[.]
|_ playbook.yml
|_ hosts
|_ [roles]
      |_ [server]
            |_ ...
      |_ [php]
            |_ ...
      |_ [mysql]
            |_ ...
      |_ [wordpress]
            |_ ...

a. server Role

1.Write server’s yml file, which does the following:

Update the apt-cache (apt-get update)
apt-get install Apache, MySQL, PHP, and related software

# roles/server/tasks/main.yml
---
- name: Update apt cache
  apt: update_cache=yes cache_valid_time=3600
  become: yes
  become_method: sudo

- name: Install required software
  apt: name={{ item }} state=present
  become: yes
  become_method: sudo
  with_items:
    - apache2
    - mysql-server
    - php5-mysql
    - php5
    - libapache2-mod-php5
    - php5-mcrypt
    - python-mysqldb

b.PHP role

will install the required PHP extensions.

roles/php/tasks/main.yml

---
- name: Install php extensions
  apt: name={{ item }} state=present
  become: yes
  become_method: sudo
  with_items:
    - php5-gd 
    - libssh2-php

c.MySQL Role

We also need to set up a MySQL database for our WordPress site. We’ll do this in the mysql role.

This role does the following:

Create a MySQL database
Create a MySQL user
Give that user access to our database

roles/mysql/tasks/main.yml

# roles/mysql/tasks/main.yml
---
- name: Create mysql database
  mysql_db: name={{ wp_mysql_db }} state=present

- name: Create mysql user
  mysql_user: 
    name={{ wp_mysql_user }} 
    password={{ wp_mysql_password }} 
    priv=*.*:ALL

We’re going to need a few variables for this one. For a role, you can specify default values for any variables in the defaults/main.yml file.

nano roles/mysql/defaults/main.yml

Add your database name, database username, and database password (that you want to create), in that order. Make sure you pick a secure wp_db_password.

roles/mysql/defaults/main.yml

---
# defaults file for mysql
wp_mysql_db: wordpress
wp_mysql_user: admin
wp_mysql_password: admin

d.WordPress

We’re adding a few different tasks to the roles/wordpress/tasks/main.yml file

First we need to download WordPress to the /tmp
extract the gzip file to /var/www, the location that Apache uses for storing web content
update Apache’s default site document root to point to our WordPress site:
Update constants in this file to match our database information:

# roles/wordpress/tasks/main.yml

# roles/wordpress/tasks/main.yml
---                                                                                                                                     
- name: Download WordPress                                                                                                              
  get_url:                                                                                                                              
    url=https://wordpress.org/latest.tar.gz                                                                                             
    dest=/tmp/wordpress.tar.gz                                                                                                          
    validate_certs=no                                                                                                                   
                                                                                                                                        
- name: Extract WordPress                                                                                                               
  unarchive: src=/tmp/wordpress.tar.gz dest=/var/www/ copy=no                                                                           
  become: yes                                                                                                                           
  become_method: sudo                                                                                                                   
                                                                                                                                        
- name: Update default Apache site                                                                                                      
  become: yes                                                                                                                           
  become_method: sudo                                                                                                                   
  lineinfile:                                                                                                                           
    dest=/etc/apache2/sites-enabled/000-default.conf                                                                                    
    regexp="(.)+DocumentRoot /var/www/html"                                                                                             
    line="DocumentRoot /var/www/wordpress"                                                                                              
  notify:                                                                                                                               
    - restart apache                                                                                                                    
                                                                                                                                        
- name: Copy sample config file                                                                                                         
  command: mv /var/www/wordpress/wp-config-sample.php /var/www/wordpress/wp-config.php creates=/var/www/wordpress/wp-config.php         
  become: yes                                                                                                                           
  become_method: sudo                                                                                                                   
                                                                                                                                        
- name: Update WordPress config file                                                                                                    
  lineinfile:                                                                                                                           
    dest=/var/www/wordpress/wp-config.php                                                                                               
    regexp="{{ item.regexp }}"                                                                                                          
    line="{{ item.line }}"                                                                                                              
  with_items:                                                                                                                           
    - {'regexp': "define\\('DB_NAME', '(.)+'\\);", 'line': "define('DB_NAME', 'wordpress');"}                                           
    - {'regexp': "define\\('DB_USER', '(.)+'\\);", 'line': "define('DB_USER', 'admin');"}                                               
    - {'regexp': "define\\('DB_PASSWORD', '(.)+'\\);", 'line': "define('DB_PASSWORD', 'admin');"}                                       
  become: yes                                                                                                                           
  become_method: sudo
                                                                                                  
# we can replace with Variables as well
  with_items:
    - {'regexp': "define\\('DB_NAME', '(.)+'\\);", 'line': "define('DB_NAME', '{{wp_mysql_db}}');"}        
    - {'regexp': "define\\('DB_USER', '(.)+'\\);", 'line': "define('DB_USER', '{{wp_mysql_user}}');"}        
    - {'regexp': "define\\('DB_PASSWORD', '(.)+'\\);", 'line': "define('DB_PASSWORD', '{{wp_mysql_password}}');"}
  become: yes
  become_method: sudo

We need to add our handler for restart apache. Save what you have so far, and open roles/wordpress/handlers/main.yml for editing:

# roles/wordpress/handlers/main.yml
---
- name: Restart Apache for Wordpress 
  service: name=apache2 state=restarted
  become: yes
  become_method: sudo

Inventory (hosts file)

Edit hosts& Add the line for [wordpress], and below it, the IP address of your wordpress-server:

hosts

[wordpress]
192.168.33.11 ansible_user=vagrant
192.168.33.12 ansible_user=vagrant

playbook.yml

root\@master:/home/vagrant/Ansible/wordpress# cat playbook.yml

---
- hosts: wordpress
  remote_user: vagrant
  become: yes
  become_method: sudo

  roles:
      - server
      - php
      - mysql
      - wordpress

Test

We’re done! Run the playbook to install and configure WordPress:

ansible-playbook playbook.yml -i hosts

sudo /etc/init.d/apache2 stop
sudo /etc/init.d/apache2 start
sudo service apache2 restart

Errors

1.”Failed to lock apt for exclusive operation”

Put:

become: yes

Now everything works as intended

-–

- hosts: all

remote_user: vagrant

become: yes

become_method: sudo

2. /usr/bin/apt-get -y -o Dpkg::Options::=–force-confdef -o Dpkg::Options::=–force-confold install ‘nginx’’ failed:

Use `force=yes` Option while doing apt:

apt: pkg=nginx state=installed update_cache=true force=yes

Ref : https://docs.ansible.com/ansible/latest/modules/apt_module.html

3 .To display OUTPUT in readable format

ANSIBLE_STDOUT_CALLBACK=debug

ansible-playbook … | sed ‘s/\\n/\n/g’

use plugin

To use it, edit your ansible.cfg file (either global, in /etc/ansible/ansible.cfg, or a local one in your playbook/project), and add the following lines under the [defaults] section:

# Use the YAML callback plugin.

stdout_callback = yaml

# Use the stdout_callback when running ad-hoc commands.

bin_ansible_callbacks = True