Ansible

• Automation tool for configuration management
• Tool for automated deployments
• Agent less
• Yaml syntax playbooks

Installation of Ansible

yum update -y && \
yum install ansible -y

Setting up Inventory

• Inventory file lists hostnames and groups in INI-like format
• Inventory file can be static or Dynamic
• Inventory file can specify IP addresses, hostnames and groups
• Inventory file can include specific parameters like non standard ports, aliases
• Default location for ansible inventory : /etc/ansible/hosts
• Inventory can also be located else where and used with -i flag by providing the path in command line
• Important to have local group as ansible communicates back to host instance

Example :

[webservers]
web1 ansible_host=www.mywebserver.com:5309

[loadbalancers]
lb ansible_host=192.168.10.2

[local]
control ansible_connection=local --> this is required to tell ansible not to ssh to local host

Inventory Commands:

ansible --list-hosts all

Setting up Ansible Configuration file

Ansible will search for configuration file in below order

1. ANSIBLE_CONFIG (environment variable if set)
2. ansible.cfg (in current directory)
3. ~/.ansible.cfg (in home directory)
4. /etc/ansible/ansible.cfg

Create ansible.cfg file in project folder, to control ansible environment settings

# ansible.cfg

[defaults]
inventory = ./inventory-file
remote_user = user_id_of_host_servers
private_key_file = ~/.ssh/ssh_key_file_of_host_servers.pem
host_key_checking = FALSE --> do not check host key finger print while ssh when connecting for first time

Ansible Tasks

Ansible tasks allows us to run adhoc commands against our inventory file. In simple terms , Task is a call to ansible module.

syntax: ansible options host-pattern
Ex: ansible -m ping all —> ansible-command module_flag module_name inventory

Using valut in Ansible

ansible-playbook -i hosts site.yml --ask-vault-pass
ansible-playbook -i hosts site.yml --vault-password-file vault-pass

Docker ansible control machine

Inorder to take advantage of the container technology, i have created a simple docker image from centos with ansible. So we can spin up a container and use this as a control machine to run ansible playbooks.
Centos Docker Image with Ansible

References

Installation Guide
Configuration File