Configuration Management with Ansible

What is Ansible?
Opensource IT Automation tool that handles:
- Application Deployment
- Muti-tier Orchestration
- Configuration Management

Why Ansible?
- Agentless architechture
- Operates over SSH
- Configuration as data and not as code
- Python
- Self Documented/Explanatory
- Feature rich - more than 150 modules - new modules are easy to write
- Full configuration management and deployment

Installing ansible:
Python package index - pip install ansible
OS Package install - sudo apt-get install ansible
Git repo and run setup.py - git clone https://github.com/ansible/ansible.git

Ansible Modes:
Playbook mode - Execution of a series of commands in order as per written in a playbook
Non Playbook mode - Executing an ansible module command on target host

Getting Started:
- Clone the parallax repo
- the repo contains a ansible.cfg file which contains following:
------------
[defaults]
# more at http://docs.ansible.com/intro_configuration.html#the-ansible-configuration-file
# host_key_checking=False
remote_user=user
-----------
This file contains global config setting to adjust ansible

Playbooks:
They represent collection of 'plays', configuration policies, which gets applied to defined groups of hosts
A sample playbook is as follows:
-----------
- name: Install all the packages and stuff required for an EXAMPLE SERVICE
  hosts: example_servers
  user: user
  sudo: yes
  roles:
    - common
    - mongodb
    - zeromq
    - service_example
    - nodejs
#    - nginx
#    - python
#    - postgresql
#    - redis
#    - memcached
#    - deployment
------------

Anatomy of a Playbook:
A sample playbook structure is as follows:
-----------
.
├── example_servers.yml
├── group_vars
│   ├── all
│   └── example_servers
├── host_vars
│   └── example-repository
├── hosts
├── repository_server.yml
├── roles
│   ├── __template__
│   ├── common
│   ├── gridfs
│   ├── memcached
│   ├── mongodb
│   ├── nginx
│   ├── nodejs
│   ├── redis
│   ├── repository
│   ├── service_example
│   └── zeromq
└── site.yml
--------------
If we look at the tree we see a few YAML files and a few directories. There is also a filed called as 'hosts'. The hosts file is the the Ansible inventory file, it stores the hosts and their mappings to the hostgroups. The hosts file looks like this.

Simple Playbook:
--- //The three dashes on the top tells you that this is a YAML(Yet another markup language) file. Ansible playbooks are written in yaml.
- name: install and start apache //"name" keyword defines the name of the play.
  hosts: webservers //"hosts" keyword tells which hosts will the play target.
  user: root //"user" keyword tells what system user will ansible use to execute the task below

 tasks: //"tasks" under tasks you can define what module you use and you configuration
- name: install httpd
  yum: name=httpd state=present //"yum" module is being used to install httpd

- name: start httpd
  service: name=httpd state=running //"service" module is being used to start the httpd service

Ansible Architechture:
It runs as a server on your laptop. It has a inventorial host and has set of modules, there are series of playbooks that define the automation tasks. It pushes the outstanding modules modules out to the managed servers using SSH, the module runs and the resukt is returned and then the module is removed from the system. No agents are necessary for this process. This is only SSH and python are the requirements.

How does a playbook work?
When you execute a palybook, the 1st thing that happens is we gather facts. Ansible will first gather lot of useful facts from that remote system. THese can be used later on in playbooks templates and config files as variables. The tasks provided in the playbook will then be performed say 'install apache'. SO we will see that we get a changed response. which means something has been changed on the systems. if you run the same playbook again you will not get the changed response for the 2nd time, as the changes were already done in the 1st run. This is because that the expected state that we told Ansible to perform was already there and hence it did not do it for the 2nd time. This is the idempotency of Ansible.

Host Inventory: Basics
Host inventory can come from several different places, it is usually a list of hosts that you organize in a group. It can come from a file or a directory of files or from a cloud provisioning environment like EC2, Rackspace etc.

contd...

Virtualization with Vagrant

 some rights reserved by MedithIT

While going ahead with Chef configuration management tutorials i came across "Vagrant". I heard this term many a times. For quite sometime i thought it was just another VirtualBox like application. until i finally started using it.

What is Vagrant?

Open Source application for creating and configuring virtual dev environment. Vagrant manages VMs hosted in VirtualBox. Basically its a commandline utility that allows you to communicate with VirtualBox (or any virtualization software) with an easy set of commands. Many describe it as a wrapper around the virtualization software too.

How is it used?

Fist of all download Vagrant for your OS from this link. Install it. As mentioned its a commandline utility tool, you need commandline to access this.

1. You will need to initialize vagrant box using the init command. This will initialize a vagrant environment in the present directory you are in. The second argument will set the name for your box and the third will set the URL to access in the Vagrant file.
   
• Syntax: vagrant init [box-name] [url-to-access]
• Example: vagrant init precise32 http://files.vagrantup.com/precise32.box
2. Next you need to create and configure the vagrant box as per your vagrant file. Use the up command for this. This command will be used frequently as this is how you start you machine as well.
   
• vagrant up
3. Now that the machine has started you still have not logged in to the machine. You can use ssh to login. You don't need to use the traditional long ssh command to login to your box a simple vagrant ssh suffices.
   
• vagrant ssh
• Note: Please check the documentation on the vagrant website as there is a list of optional parameters that you may need in case you run into any errors. Fatal can be expected.
4. To check valid configurations to ssh into a running vagrant box use vagrant ssh-config
• vagrant ssh-config
5. As you now know how to setup and start using your vagrant box, we also need to know how to shut it down. This is simple too by just a "vagrant halt" similar to the halt command in linux machine.
• vagrant halt
6. These were the few basics of vagrant. You can do more with vagrant as well. The vagrant box command gives you other alternatives that you could try out.
• vagrant box add [box-name] [url-path]
• This adds a box with the specified name using the local file path or url specified to access it.
• vagrant box list
• Lists all the boxes installed and available
• vagrant box remove [box-name] [provider]
• Removes the box with the specified box name for the specific provider. Providers are VirtualBox or VMWare or any other utility.
• vagrant box repackage [box-name] [provider]
• Repackages the given box and puts it to present directory for redistribution purpose. When a box is added, vagrant unpacks and stores it internally and the original box is not preserved.
7. Restarting a vagrant machine can be done using vagrant reload. Its equivalent to a vagrant halt and vagrant up.
• vagrant reload
8. To check the current state of the machine, i.e to verify if the machine is running, stopped or not created etc a status command helps
• vagrant status
9. To save the status of the machine and suspend it so that you can resume it at a later instance and not completely shut it down, you can use suspend command.
• vagrant suspend
10. To resume a suspended machine use vagrant resume
• vagrant resume
11. Finally, to stop and delete/destroy and existing machine use the destroy command. All the resources allocated are destroyed as if the machine was never there. This command asks for confirmation before destroying.
• vagrant destroy

Free and Open Source Alternatives for most of the paid softwares on Windows Machine

 Some rights reserved by opensource.com

I have recently been using windows more than usual for official use. Being an Ubuntu user i am not much used to either use a trial version of any paid software or pay for any software. I googled a lot for my daily use softwares to make my life comfortable and found that almost for every paid software there was an alternative in the Free and Open Source World. Here is what i found:

• Operating System : Widows (Paid) -> ReactOS (Alternative) I have a different blog written for this.
• Office Utility : Microsoft Office (Paid) -> Libre Office, Open Office(Alternative). For years i only knew about Open Office as an open source alternative. However after going through the threads on Ubuntu forums as to why was Libre Office considered over Open Office as a default Office utility for the OS i came to know that Libre Office development was far too faster than that of Open Office. I even saw the results myself to verify this fact. I would recommend Libre Office for the same reason.
• Video/Music Player : Windows Media Player (Most Probably Paid - I have hardly heard of Microsoft ever releasing anything free of cost :D) -> VLC media Player, Media Player Classic(Alternative).
• Remote File Sharing : WinSCP, FileZilla, Putty
• IDE for C# Programming : Microsoft Visual Studio (Paid) -> Sharp Develop (Alternative) (Although i was looking for Command line utility as i am only used to VIM as such, but found this one and made a note of it.
• File Compression : WinRAR, WinZIP(Paid) -> 7zip(Alternative)
• PDF Reader : Adobe Acrobat Reader(Freeware+Commercial) -> Foxit(Alternative)
• Email Client : Outlook(Paid) -> Thunderbird(Alternative)
• VM : VMWare(Paid) -> VirtualBox(Alternative)
• Reference Management : Zotero (Zotero is another good add-on cum software for Reference Management. You can save your websites and URL/PDF preferences online so that whenever you clean your cache on browsers and you desperately needed some link and you cleared your cache and reinstalled new browser. You can check your Zotero and get URL/PDF back as all these preferences are stored online in your separate account.)
• Cloud Storage : GoogleDrive/Dropbox