Getting started with Ansible and Oracle

Introduction

In my previous post An introduction to Ansible I shared some reasons why companies are adopting Ansible and described some of the advantages of using Ansible over other configuration management tools.

Now we know what Ansible is, let’s start using it.

Setting up an Ansible Control Machine

The simplest and quickest way to get up and running with Ansible is to use Vagrant to create a virtual machine. Vagrant ships with out of the box support for VirtualBox, Hyper-V and Docker. Vagrant supports other providers e.g. VMware but these are licenceable

So even though I mainly use VMware Fusion on my MacBook I used the links above to install Vagrant and the excellent Oracle VirtualBox to avoid any licensing requirements.

Using Vagrant

Run the following commands to create a Vagrantfile for an Ubuntu Vagrant machine.
$ mkdir ansible_oracle
$ cd ansible_oracle
$ vagrant init ubuntu/trusty64

A `Vagrantfile` has been placed in this directory. You are now ready to `vagrant up` your first virtual environment! Please read the comments in the Vagrantfile as well as documentation on `vagrantup.com` for more information on using Vagrant.

$ vagrant up
You should now be able to SSH into your Ubuntu VM using ‘vagrant ssh’, however before we try and connect to our new VM let’s check the status of all the local Vagrant machines using the following:
$ vagrant global-status

id       name    provider   state    directory
————————————————————————-
a1995ac  default virtualbox running  /Users/ronekins/ansible_oracle

The above shows information about all known Vagrant environments
on this machine. This data is cached and may not be completely
up-to-date. To interact with any of the machines, you can go to
that directory and run Vagrant, or you can use the ID directly
with Vagrant commands from any directory. For example:
“vagrant destroy 1a2b3c4d”

$ vagrant status a1995ac
Current machine states:

default running (virtualbox)

The VM is running. To stop this VM, you can run `vagrant halt` to
shut it down forcefully, or you can run `vagrant suspend` to simply
suspend the virtual machine. In either case, to restart it again,
simply run `vagrant up`.

$ vagrant ssh
If all has gone well you should be presented with your Ubuntu virtual machine.

Useful vagrant machine (vm) commands

destroy       : stops and deletes all traces of the vm 
global-status : outputs status Vagrant env's for this user 
halt          : stops the vm 
init          : initialises a new Vagrant environment 
provision     : provisions the vm 
reload        : restarts vm, loads new Vagrantfile config 
resume        : resume a suspended vm 
snapshot      : manages snapshots, saving, restoring, etc. 
ssh           : connects to vm via SSH 
status        : outputs status of the vm 
suspend       : suspends the vm 
up            : starts and provisions the vm

Ansible Installation

$ sudo apt-get install software-properties-common
$ sudo apt-add-repository ppa:ansible/ansible
$ sudo apt-get update
$ sudo apt-get install ansible

Update local host file

Add the IP address and database server names to your local host file.
$ sudo vi /etc/hosts

Getting Started

Create Ansible configuration file

$ vi ansible.cfg
[defaults]
hostfile = hosts
ansible_private_key_file=~/.ssh/id_rsa

Create Ansible host file

In the host file we can specify that we want ansible to default to the ‘oracle’ user, the first entry is a server alias, in the example below I have kept it the same as the server name but it can be useful if you have cryptic host names or want to refer to the server by it’s database or application name.
$ vi hosts
[dbservers]
z-oracle         ansible_host=z-oracle        ansible_user=oracle
z-oracle-dr  ansible_host=z-oracle-dr  ansible_user=oracle

Ansible Ping Test

Now let’s try using the Ansible ping module to try to connect to our database server and verify a usable version of python, the ping module will return ‘pong’ on success.
$ ansible all -m ping

Both servers will fail returning UNREACHABLE! as the ssh connection failed, to fix this add a public key to the database servers ‘authorized_keys’file.

Generating RSA Keys

Before we can use password-less SSH we need to create a pair of private and public RSA keys for our Ansible control machine.

$ cd ~/.ssh
$ ssh-keygen -t rsa
$ cat id_rsa.pub

‘Copy’ the id_rsa.pub into your client buffer and ssh onto the database servers as the ‘oracle’, cd to the .ssh directory and ‘paste’ the public key into the ‘authorized_keys’ file.

$ cd ~/.ssh
$ vi authorised_keys

Now return to your Ansible control machine to repeat the Ansible Ping Tests.

Ansible Ping Part II

Ok, now we are ready to check connectivity, first lets trying using the database server names individually.
ping_each
That was great, but as we defined a group ‘dbservers’ we can also perform a ‘ping’ test using the group name as we may want to perform an ansible play against a group of servers e.g. Production, Development, Test etc..

ping_group
Very cool, if required you can use the ‘all’ option to run against all entries in the host file.

ping_all
In my next blog post we will start to use our Ubuntu Ansible control machine to interact with our database servers.

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