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Before starting download the hands-on repository and move inside the directory as follow:

git clone https://github.com/DODAS-TS/SOSC-2018.git
cd SOSC-2018

Automation with Ansible

What's Ansible

Ansible is a software that consistently automatize the configuration management. The Ansible configurations are a set of minimal infrastracture descriptions that are easy to read and to mantain, reducing the amount of work needed to setup environment and softwares on data centers or even on a laptop. Ansible does not require any remote agents and delivers all modules to remote systems that execute tasks, as needed, to deploy the desired configuration. Ansible Galaxy also has over 4,000 community-provided roles that can be used by anyone and tailored to different environments.

In this hands-on we are going to deploy a simple web server application as a first introduction to Ansible recipes.

Hello word: install and deploy a webserver with Ansible

Playbooks

Playbooks are the Ansible building blocks. They describe the desired infrastracture with a sequence of states and checks, that will be automatically deployed at installation time. Ansible infact implements a "state-driven" paradigm, that does not indicate the exact chain of commands but instead check a sequential list of machine state. But let's do an exercise to understand better the basics.

• install the apache2 packages on localhost

---
- hosts: localhost
  connection: local
  tasks:
  - name: Apache | Make sure the Apache packages are installed
    apt: name=apache2 update_cache=yes
    when: ansible_os_family == "Debian"

  - name: Apache | Make sure the Apache packages are installed
    yum: name=httpd
    when: ansible_os_family == "RedHat"

• start services after configuration customization

---
- hosts: localhost
  connection: local
  tasks:
  - name: Configure apache 1/2
    get_url:
      force: true
      url: https://raw.githubusercontent.com/DODAS-TS/SOSC-2018/master/templates/hands-on-1/apache-config/port.conf
      dest: /etc/apache2/ports.conf

  - name: Configure apache 2/2
    get_url:
      force: true
      url: https://raw.githubusercontent.com/DODAS-TS/SOSC-2018/master/templates/hands-on-1/apache-config/000-default.conf
      dest: /etc/apache2/sites-enabled/000-default.conf

  - name: Start Apache service
    service: name=apache2 state=restarted
    when: ansible_os_family == "Debian"

  - name: Start Apache service
    service: name=httpd state=restarted
    when: ansible_os_family == "RedHat"

Run the playbooks

• install the apache2 packages on localhost

ansible-playbook templates/hands-on-1/ansible-role-install.yml

• start services after configuration customization

ansible-playbook templates/hands-on-1/ansible-role-apache.yaml

• the apache default webpage should now being served at localhost:4880

N.B. with this simple configuration files we will be able to reproduce with a single command the current state on different machines. Of course this is a very simple software installation that is meant as demonstrator, but in principle can be much more complicated.