Ansible

how to install on command and control server

First step install Ansible on your command and control server (laptop or workstation, lol). This section shows the process I used on Fedora.

install system dependancy

sudo yum -y install sshpass

clone the git repo and create python virtualenv

git clone git://github.com/ansible/ansible.git
cd ansible
virtualenv .env

source the environment scripts

source ./hacking/env-setup
source ./.env/bin/activate 

install ansible and dependencies into python virtualenv

python setup.py develop

create an ansible hosts file in /etc/ansible/hosts

sudo mkdir /etc/ansible
sudo vim /etc/ansible/hosts

put your targets into /etc/ansible/hosts for example

127.0.0.1

and test!

ansible all -m ping --ask-pass

Ansible assumes SSH keys, but may also use passwords, which is invoked with the --ask-pass flag. Invoke the --ask-sudo-pass flag if you need to supply a sudo password.

ansible configuration files

By default ansible looks to /etc/ansible for its configurations. In this section we document some of the configuration files ansible works with.

/etc/ansible/hosts

This file lists all ansible managed hosts and group mappings.

/etc/ansible/host_vars

This directory may hold one YAML file for each host. These files are used to pass host specific variables.

/etc/ansible/group_vars

This directory may hold one YAML file for each group. These files are used to pass group specific variables.

/etc/ansible/group_vars/all

This is a special group that matches all hosts and groups and holds variables for all hosts.

Behavioral inventory variables and parameters

Sometimes you always want to set specific Ansible/SSH/settings for a host, group of hosts, or all hosts.

For example, this all file causes Ansible to use the root SSH user:

---
ansible_ssh_user: root

Another example declares the parameters in the hosts file itself.

/etc/ansible/hosts:

node1.example.com          ansible_ssh_private_key_file=/home/example/.ssh/aws.pem

Here is a list of other behavioral inventory parameters which may be set in a host_vars or group_vars files: http://docs.ansible.com/intro_inventory.html#list-of-behavioral-inventory-parameters

how to prepare remote hosts

Ansible requires that remote hosts have an SSH service running, and that your public SSH key is setup. Ansible also requires that all remote hosts have Python 2.4.x and the python JSON library (python-simplejson). Python 2.6.x and above ship with JSON library in the stdlib, so nothing needs to be done if you are using a newer operating system.

quick notes

run arbitary commands

ansible all --ask-pass -a "uptime"

get all facts

ansible all --ask-pass -m setup

change the amount of parallel forks, (default is 5)

ansible all --ask-pass -f 20 -a "uptime" 

give path to a private key

ansible tutorial_nodes --private-key=id_rsa -m shell -a 'free -m'