Ansible Inventory file and config file

Ansible is an automation tool which works for multiple systems in a infrastructure at the same time. So we should have system lists to manage it. We call that as inventory. Ansible inventory file has the list of all managed hosts names one line per host.

By default, this ansible host inventory file is located under /etc/ansible/hosts. Hence if you run a Ansible playbook or Ansible Ad-hoc commands, that will look the hosts groups under the default group file. You can specify a different inventory file using the “-i <path>”  option on the command line as shown below.

ansible-playbook –i  /opt/database_server install.yml

To authenticate to remote servers we may need to enable password less authentication between control and slave machines or we may need to pass password from cli.

Hosts group declaration:

We can declare the different groups in single host inventory file. For example, if you have database and web servers, then we can declare the list of server names under each groups.

[database-servers]

host1.database

host2.database

[web-servers]

Web1.webapp

Web2.webapp

Note: A host can be in more than one group.

Inventory file parameters

By default ansible works on SSH port number 22. If you have different port to connect the 

hosts, then define the hosts as below.

Web1.webapp:2209

We can also define the connection type and also user depends on target hosts.

[web-servers]

Web1.webapp ansible_connection=ssh ansible_user=vagrant

Web2.webapp ansible_connection=ssh ansible_user=vagrant

ansible.cfg file

The ansible configuration file has many parameters like inventory file location, library location, modules and etc. All these default values are commented. If you wanted to change the default behaviour of any parameter, Just uncomment and change the value.

Changes can be made and used in a configuration file which will be searched for in the following order:

• ANSIBLE_CONFIG (environment variable if set)
• ansible.cfg (in the current directory)
• ~/.ansible.cfg (in the home directory)
• /etc/ansible/ansible.cfg

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