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First steps

Basic project layout

A basic Ansible project contains only the inventory file, which contains the metadata about the remote hosts and is necessary for Ansible to work. A simple representation of our current training environment could be depicted by the following inventory:

# hosts.ini
[centos]
provisioner     ansible_connection=local
centos1         ansible_host=192.168.77.22

[ubuntu]
ubuntu1         ansible_host=192.168.77.23

Note

Inventory files are commonly named hosts.<file_extenstion>.

Another component that is commonly found in Ansible environments is the configuration file eg.:

#ansible.cfg
[defaults]
inventory = hosts.ini
host_key_checking = False
deprecation_warnings = False

The configuration file stores various options that are responsible for different aspects of Ansible's behavior. You can check the list of configurable settings in the official documentation.

Configuration file hierarchy

Ansible's configuration files can be stored in different locations, but only a single one will be used during Ansible execution.

Let's make a simple experiment:

  • open a terminal session on the provisioner/SSH connection to the provisioner and enter the training directory 

    cd ansibletraining

  • create a temporaty directory 

    mkdir temp

  • inside this temporary directory create a hosts.ini file and copy the contents of the inventory mentioned in the previous section 

    cd temp
# then create hosts.ini with a text editor of your choice

  • create an ansible.cfg in the same manner

  • execute the following chain of commands 

    xargs -n 1 cp -v ansible.cfg<<<"/home/vagrant/ANSIBLE.cfg /home/vagrant/.ansible.cfg"
sudo mkdir -p /etc/ansible
sudo cp ansible.cfg /etc/ansible
export ANSIBLE_CONFIG=$HOME/ANSIBLE.cfg

  • run ansible --version and find the value of config file

  • execute unset ANSIBLE_CONFIG and repeat the previous process

Important

If we continued with this chain of thought the result would yield the following precedence of configuration file locations:

  • ANSIBLE_CONFIG environment variable
  • ansible.cfg in the current directory
  • ~/.ansible.cfg in the home directory
  • /etc/ansible.cfg systemwide Ansible configuration

Testing the connectivity

As previously established Ansible works by pushing executable code through SSH. Connectivity to remote hosts can be tested using the ping module. Inside the temp directory execute:

ansible all -m ping
What is the expected result of the command?

Only provisioner will be reachable since we have not set up SSH connectivity to the remote hosts.

Bonus round

Fix the problems with connectivity by creating a SSH keypair and copying the SSH public key to the remotes.

  • generate a new SSH key pair on provisioner (accept all prompts) 

    ssh-keygen -C ""

  • copy the generated private key to centos1 and ubuntu1 (the SSH password is vagrant in both cases) 

    ssh-copy-id -i ~/.ssh/id_rsa.pub vagrant@192.168.77.22
ssh-copy-id -i ~/.ssh/id_rsa.pub vagrant@192.168.77.23

  • run the connectivity check once more 

    ansible all -m ping