Ansible

Installation

From source

$ git clone https://github.com/ansible/ansible.git && cd ansible
$ git submodule update --init --recursive
# sudo apt-get install python-paramiko python-yaml python-jinja2 python-httplib2 python-setuptools python-six sshpass
# sudo apt-get install cdbs debhelper dpkg-dev git-core reprepro python-support fakeroot asciidoc devscripts docbook-xml xsltproc
$ make deb
# dpkg -i ../ansible_XXX.deb

or from the package manager

# apt-get install ansible

Our advice is to use source.

Usage

Ansible is based on playbook: Playbook contains Plays contains Tasks calls Modules, Handlers can be triggered by tasks. The principal tool is ansible-playbook that reading a playbook executes the necessary tasks.

First of all the tool used to connect is SSH, the host to which connect to is indicated into the inventory file.

The default inventory is /etc/ansible/hosts but you can pass another with the --inventory-file parameter; the inventory can store alias, variable, etc. There are also a lot of variables used by ansible itself.

A simple example di inventory is the following

vagrant ansible_ssh_host=127.0.0.1 ansible_ssh_port=2222 ansible_ssh_private_key_file=~/.vagrant.d/insecure_private_key ansible_ssh_user=root

It's possible also to launch ansible without playbook if you want to execute a single module, like the following

$ ansible -i <inventory> all -m setup --tree /tmp/facts

In the official documentation there is more.

Generally the form of usage is

$ ansible-playbook         \
    --inventory-file=vagrant_inventory                \
    --private-key=~/.vagrant.d/insecure_private_key   \
    --user=root         \
    --skip-tag certs    \
    playbook.yml

Template

The configuration is described using YAML file, and internally are parsed using the Jinja2 template system.

Roles

Since we want to reuse configuration across projects (that is the aim of this project) we are using the roles.

The roles available are

• common: configure locale and install extra packages needed
• database: install and configure postgres, create an user and a database
• nginx: install and configure an available site
• repo: create a bare repository
• webapp: create an UNIX user and allow access by SSH key
• workers: install redis

Vagrant

In order to provision with it

  config.vm.provision "ansible" do |ansible|
    ansible.playbook = "provisioning/playbook.yml"
    #ansible.verbose  = 'vvvv'
    ansible.extra_vars = {
        ansible_ssh_user: 'root',
        db_user: "astauser",
        db_name: "astadb",
        db_password: "asta"
    }
  end

Weirdness

The commands executed server side sometimes do not use environment variables like LC_* so for example to set correctly the database encoding it's tricky