Start Project

This Ansible project is specifically for working with dynamic AWS EC2 instance inventory, create the following three directories (assuming your already in ~/ansible from the previous page):

mkdir playbooks plugins roles

AWS EC2 Plugin

Add the following file plugins/aws_ec2.yaml:

plugins/aws_ec2.yaml

plugin: aws_ec2

aws_access_key: "{{ lookup('env', 'AWS_ACCESS_KEY') }}"
aws_secret_key: "{{ lookup('env', 'AWS_SECRET_KEY') }}"

regions:
  - eu-west-1

keyed_groups:
  - key: tags
    prefix: tag

Configuration

Under playbooks, create another subdirectory aws and change into it:

mkdir playbooks/aws && cd playbooks/aws

Add the following ansible.cfg file with the correct path to your AWS private key:

playbooks/aws/ansible.cfg

[defaults]
inventory = ../../plugins
roles_path = ../../roles
host_key_checking = False
retry_files_enabled = False
command_warnings = False
remote_user = ec2-user
private_key_file = <PATH_TO_PRIVATE_KEY>
deprecation_warnings=False

[privilege_escalation]
become = true
become_method = sudo
become_user = root
become_ask_pass = false

Testing

With this configuration and plugin in place, test to see if your EC2 instances are returned:

ansible-inventory --list

The plugin was configured with keyed_groups, see how the inventory returns the tag groups using:

ansible-inventory --graph

Then instances can be targeted using the tag group name, for example:

ansible tag_project_exampleforyou -m ping

With everything working, test a basic playbook, for example smoke_test.yaml. Notice that hosts: is targeting the tag derived previously:

- name: smoke test playbook
  hosts: tag_project_exampleforyou
  become: yes
  tasks:
    - shell: echo 'Hello World' > /tmp/test.txt

And run the playbook:

ansible-playbook smoke_test.yaml

SSH to the EC2 instance and check the result:

ssh -i example-key.pem ec2-user@46.137.7.7

cat /tmp/test.txt

General Configuration

The best practice is to create an ansible.cfg file in a directory from which you run Ansible commands. This directory would also contain any files used by your Ansible projects, such as inventories and playbooks. This is the most common location used for the Ansible configuration file. It is unusual to use a ~/.ansible.cfg or /etc/ansible/ansible.cfg file in practice. You can also use the ANSIBLE_CONFIG environment variable.

Run ansible --version command to identify which version of Ansible is installed, and which configuration file is being used.

A typical ansible.cfg file:

[defaults]
inventory = ./inventory
remote_user = user
ask_pass = false

[privilege_escalation]
become = true
become_method = sudo
become_user = root
become_ask_pass = false

An adhoc command is a way of executing a single Ansible task.

Use the ansible command to run adhoc commands:

ansible host-pattern -m module [-a 'module arguments'] [-i inventory]

Example:

ansible all -m ping

134.209.21.255 | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python"
    },
    "changed": false,
    "ping": "pong"
}

The ansible-doc -l command lists all modules installed on a system. Use ansible-doc to view the documentation of the particular module, for example ansible-doc ping.

The following section provide a quick reference to the core concept's, but to jump into creating custom roles to deploy the FastAPI application skip to here: First Role