Configure Load Balancer and Webserver Using Ansible Roles

What is Ansible ?

Ansible is an open-source software provisioning, configuration management, and application-deployment tool enabling infrastructure as code. It runs on many Unix-like systems, and can configure both Unix-like systems as well as Microsoft Windows. Ansible is agentless, temporarily connecting remotely via SSH or Windows Remote Management (allowing remote PowerShell execution) to do its tasks.

What is Ansible Role ?

Writing ansible code to manage the same service for multiple environments or different products increase code redundancy. With more complexity in functionality, it becomes difficult to manage everything in one ansible playbook file. Sharing code among teams become difficult.

Ansible Role helps solve these problems. Ansible role is an independent component which allows reuse of common configuration steps. Ansible role has to be used within playbook. Ansible role is a set of tasks to configure a host to serve a certain purpose like configuring a service. Roles are defined using YAML files with a predefined directory structure.

A role directory structure contains directories: defaults, vars, tasks, files, templates, meta, handlers. Each directory must contain a main.yml file which contains relevant content. Let’s look little closer to each directory.

1. defaults: contains default variables for the role. Variables in default have the lowest priority so they are easy to override.
2. vars: contains variables for the role. Variables in vars have higher priority than variables in defaults directory.
3. tasks: contains the main list of steps to be executed by the role.
4. files: contains files which we want to be copied to the remote host. We don’t need to specify a path of resources stored in this directory.
5. templates: contains file template which supports modifications from the role. We use the Jinja2 templating language for creating templates.
6. meta: contains metadata of role like an author, support platforms, dependencies.
7. handlers: contains handlers which can be invoked by “notify” directives and are associated with service.

Task Description📄

🔅Create an ansible role myapache to configure Httpd WebServer.

🔅Create another ansible role myloadbalancer to configure HAProxy LB.

🔅We need to combine both of these roles controlling webserver versions and solving challenge for host ip’s addition dynamically over each Managed Node in HAProxy.cfg file.

Let’s start doing our task:-

⚠️ Note: By Default Ansible provide some path to keep role

 /root/.ansible/roles does 
 /usr/share/ansible/roles 
 /etc/ansible/roles 

either we can keep our roles here or we can also change , if we want to keep roles in our workspace then we have to tell Ansible where our roles are available , we have to write roles path in ansible config file , I will keep roles in “/myroles” , let’s update this path to ansible config file

vim /etc/ansible/ansible.cfg
roles_path=/myroles

ansible.cfg

🔅Create an ansible role myapache to configure Httpd WebServer.

Let’s create a Ansible role to configure httpd server

for creating new role

ansible-galaxy role init myapache

myapache role created successfully

when we run “ ansible-galaxy role init myapache” command they automatically create a structure for us , this structure look like this

now let’s start writing our task here,

vim task/main.yml

---
# tasks file for myapache
- package:
     name: "{{ item }}"
     state: present
  loop:
    - httpd
    - php
- copy:
     dest: /var/www/html
     src: files/index.php
- service:
     name: "{{ service_name }}"
     state: started

vim vars/main.yml

---
# vars file for apache
service_name: "httpd"

vim files/index.php

<pre>
<?php
print `/usr/sbin/ifconfig`;
?>
</pre>

now our final role structure is look like this :-

This role will configure webserver for us.

Let’ s move to another step :-

🔅Create another ansible role myloadbalancer to configure HAProxy LB.

ansible-galaxy role init myloadbalancer

now let’s start writing our task detail in role-

vim tasks/main.yml

---
# tasks file for myloadbalancer
- name: Install the Haproxy package
  package:
     name: "{{ package_name }}"
     state: present
- name: Change the config file of haproxy
  template:
     dest: /etc/haproxy/haproxy.cfg
     src: templates/haproxy.cfg.j2
  notify:
  - Restart the service
- name: Start the service
  service:
     name: "{{ service_name }}"
     state: started
     enabled: yes

vim vars/main.yml

---
# vars file for myloadbalancer
#
package_name: haproxy
service_name: haproxy
fsp: 8080
bsp: 80

vim handlers/main.yml

---
# handlers file for myloadbalancer
- name: Restart the service
  service:
     name: "{{ service_name }}"
     state: restarted

vim templates/haproxy.cfg.j2

#---------------------------------------------------------------------
# Example configuration for a possible web application.  See the
# full configuration options online.
#
#   https://www.haproxy.org/download/1.8/doc/configuration.txt
#
#---------------------------------------------------------------------
#---------------------------------------------------------------------
# Global settings
#---------------------------------------------------------------------
global
    # to have these messages end up in /var/log/haproxy.log you will
    # need to:
    #
    # 1) configure syslog to accept network log events.  This is done
    #    by adding the '-r' option to the SYSLOGD_OPTIONS in
    #    /etc/sysconfig/syslog
    #
    # 2) configure local2 events to go to the /var/log/haproxy.log
    #   file. A line like the following can be added to
    #   /etc/sysconfig/syslog
    #
    #    local2.*                       /var/log/haproxy.log
    #
    log         127.0.0.1 local2
chroot      /var/lib/haproxy
    pidfile     /var/run/haproxy.pid
    maxconn     4000
    user        haproxy
    group       haproxy
    daemon
# turn on stats unix socket
    stats socket /var/lib/haproxy/stats
# utilize system-wide crypto-policies
    ssl-default-bind-ciphers PROFILE=SYSTEM
    ssl-default-server-ciphers PROFILE=SYSTEM
#---------------------------------------------------------------------
# common defaults that all the 'listen' and 'backend' sections will
# use if not designated in their block
#---------------------------------------------------------------------
defaults
    mode                    http
    log                     global
    option                  httplog
    option                  dontlognull
    option http-server-close
    option forwardfor       except 127.0.0.0/8
    option                  redispatch
    retries                 3
    timeout http-request    10s
    timeout queue           1m
    timeout connect         10s
    timeout client          1m
    timeout server          1m
    timeout http-keep-alive 10s
    timeout check           10s
    maxconn                 3000
#---------------------------------------------------------------------
# main frontend which proxys to the backends
#---------------------------------------------------------------------
frontend main
    bind *:{{ fsp }}
    acl url_static       path_beg       -i /static /images /javascript /stylesheets
    acl url_static       path_end       -i .jpg .gif .png .css .js
use_backend static          if url_static
    default_backend             app
#---------------------------------------------------------------------
# static backend for serving up images, stylesheets and such
#---------------------------------------------------------------------
backend static
    balance     roundrobin
    server      static 127.0.0.1:4331 check
#---------------------------------------------------------------------
# round robin balancing between the various backends
#---------------------------------------------------------------------
backend app
    balance     roundrobin
  {% for i in groups['Backend_servers'] %}
    server  app{{ loop.index }} {{ i }}:{{ bsp }} check
{% endfor %}

final structure of myloadbalancer role

This role will configure loadbalancer for us.

🔅We need to combine both of these roles controlling webserver versions and solving challenge for host ip’s addition dynamically over each Managed Node in HAProxy.cfg file.

vim setup.yml
---
- hosts: localhost
  roles:
     - role: "myloadbalancer"
- hosts: Backend_servers
  roles:
     - role: "myapache" 

save this file, and run this playbook

ansible-playbook setup.yml

Playbook runs succesfully

Let’s check

paste your loadbalancer IP in your browser

http://IP_of_Loadbalancer:Portno

load balancer is working properly.

Task has been done!!

Thanks for reading.