Overview

This vagrant based and ansible assisted automation will help us to setup a lab to build a tier3 infrastructure and learn the ansible usage.

The lab will implement the following configuration when completed:

----------------|---------------|----------------------------------------|----------------------------|

Machine Name	Role	Network Configuration Details	Linux OS
control	Ansible Host	private_network, ip: 192.168.135.101	Ubuntu bionic64 (18 LTS)
lb01	Load Balancer	private_network, ip: 192.168.135.102	Ubuntu bionic64 (18 LTS)
app01	Web server 1	private_network, ip: 192.168.135.103	Ubuntu bionic64 (18 LTS)
app02	Web server 2	private_network, ip: 192.168.135.104	Ubuntu bionic64 (18 LTS)
db01	MySql DB	private_network, ip: 192.168.135.105	Ubuntu bionic64 (18 LTS)
----------------	---------------	----------------------------------------	----------------------------

Quick Start

• Clone this repo

• Install the hostmanager Vagrant plugin if ytou haven't already vagrant plugin install vagrant-hostmanager

  • on a Mac Vagrant host, brew install libffi was required prior to installing the plugin successfully

• run vagrant up from the root of the synced repo (the folder with Vagrantfile in it)

• Once the VMs are built, type vagrant ssh control to logon to the ansible controller from within your vagrant project folder

• Change directories cd /vagrant/ansible which is the ansible subfolder of your vagrant project for this lab (the vagrant project folder is mounted within the VMs as /vagrant during provisioning)

• run ansible-playbook playbooks/site.yml to build the entire 3 tier configuration (load balancer, sample web app, and database connection)

• run ansible-playbook playbooks/stack_status.yml to validate status of each component

• test that the application stack is working properly end to end by running curl http://lb01/db

#Exploring the details Inventory

• ./hosts
  • file defining the servers to be orchestrated Ansible Configuration
• ./ansible.cfg
  • defines hosts file location and ansible vault password file location Group vars
• ./group_vars/all/vars
  • global variables file, includes database name and login user info
• ./group_vars/all/vault
  • file encrypted containing database user password (vault_db_pass)
  • you can view and edit the file with ansible-vault edit group_vars/all/vault - your decryption key specified in ansible.cfg will be used to decrypt and reencrypt the file transparently

Ansible Playbooks:

• ./site.yml - main playbook wrapper, which includes playbooks for the various server types, such as loadbalancer.yml, for building the front end load balancer

• ./loadbalancer.yml

• defines affected hosts ("loadbalancer", which in turn is a group defined in ./hosts file)

• references the role of type nginx, which means to include running the playbook in playbooks/roles/tasks/main.yml

• (same idea for database.yml, control.yml, webserver.yml)

• ./playbooks/roles/nginx (same concept for each role in playbooks/roles/*)

  • ./playbooks/roles/nginx/defaults/main.yml variable defaults
  • ./playbooks/roles/nginx/vars/main.yml variables, if defined here would override the ones in defaults folder
  • ./playbooks/roles/nginx/handlers/main.yml handler definitions for "notify" actions in tasks
  • ./playbooks/roles/nginx/tasks/main.yml task step definitions
  • ./playbooks/roles/nginx/templates/nginx.conf.j2 config file template, used in the "configure nginx site" step in tasks/main.yml, using the "template:" module to customize the .j2 file template into nginx.conf

Ansible syntax samples

##Selecting and filtering hosts to work with

#####selecting hosts ansible --list-hosts all ansible --list-hosts "*"

####name of group in hosts file ansible --list-hosts loadbalancer

####wildcard filter ansible --list-hosts "app*"

####multiple groups separated by a colon (deprecated) ansible --list-hosts database:control

####multiple groups separated by a comma ansible --list-hosts database,control

####select first node in webserver group ansible --list-hosts webserver[0]

####everything not in control group, bang escaped in bash ansible --list-hosts !control

##simple commands

####internal ping module ansible -m ping all

####command module (-m) executing "hostname" command (-a) ansible -m command -a "hostname" all

####command with just -a is equiv, as command module is default module ansible -a "hostname" all

####show what hosts are involved in this playbook ansible-playbook playbooks/site.yml --list-hosts

####show what tags are involved in this playbook ansible-playbook playbooks/site.yml --list-tags

using playbooks

####simple playbook that executes "hostame" command ansible-playbook /vagrant/playbooks/hostname.yml

####run only steps in a playbook that have a tag called "packages" defined ansible-playbook playbooks/site.yml --tags "packages"

####run only steps in a playbook that DON'T have a tag called "packages" defined ansible-playbook playbooks/site.yml --skip-tags "packages"

####step through tasks and be prompted whether to run each step or not ansible-playbook playbooks/site.yml --step

####show all tasks that will be executed by the playbook ansible-playbook playbooks/site.yml --list-tasks

####skip over steps in a playbook and start at a specific task ansible-playbook playbooks/stack_status.yml --start-at-task "verify end-to-end response"

####verify syntax ansible-playbook --syntax-check playbooks/site.yml

####do a simulated run of the playbook ansible-playbook --check playbooks/site.yml

##Utilities

gather facts available

ansible -m setup all