Installing and Setting Up Ansible

Getting Ansible up and running is straightforward. Unlike other configuration management tools, you only need to install Ansible on one machine (called the "control node") - the servers you'll manage don't need any special software installed.

Installing Ansible

The installation method depends on your operating system and preferences. Here are the most reliable approaches:

On macOS with Homebrew

If you're using macOS, Homebrew provides the simplest installation:

brew install ansible

This installs the latest stable version along with all necessary dependencies.

On Ubuntu/Debian

For Ubuntu and Debian systems, use the official package repository:

# Add the Ansible PPA for the latest version
sudo apt update
sudo apt install software-properties-common
sudo add-apt-repository --yes --update ppa:ansible/ansible

# Install Ansible
sudo apt install ansible

The PPA ensures you get recent versions rather than the older packages in the default repositories.

Using pip (Universal)

If you prefer Python's package manager or need the latest features:

# Install using pip3
pip3 install ansible

# Or install in a virtual environment (recommended)
python3 -m venv ansible-env
source ansible-env/bin/activate
pip install ansible

Using a virtual environment prevents conflicts with other Python packages on your system.

Verifying Your Installation

Check that Ansible installed correctly:

ansible --version

You should see output showing the Ansible version, Python version, and configuration file locations. Something like:

ansible [core 2.14.2]
  config file = None
  configured module search path = ['/home/user/.ansible/plugins/modules', '/usr/share/ansible/plugins/modules']
  ansible python module location = /usr/lib/python3/dist-packages/ansible
  ansible collection location = /home/user/.ansible/collections:/usr/share/ansible/collections
  executable location = /usr/bin/ansible
  python version = 3.10.6

Preparing Your Servers

Ansible connects to remote servers using SSH, so you'll need SSH access to the machines you want to manage. Here's how to set this up properly:

SSH Key Authentication

Password authentication works, but SSH keys are more secure and convenient for automation. If you don't already have SSH keys set up:

# Generate a new SSH key pair
ssh-keygen -t ed25519 -C "[email protected]"

# Copy your public key to the target server
ssh-copy-id user@server-ip-address

Replace user with the username you'll use on the remote server, and server-ip-address with your server's IP address or hostname.

Testing SSH Access

Verify you can connect without entering a password:

ssh user@server-ip-address

If this works without prompting for a password, you're ready to use Ansible.

Your First Ansible Command

Ansible can run individual commands across servers without writing any configuration files. This "ad-hoc" mode is perfect for quick tasks and testing connectivity.

Testing Connection

Let's verify Ansible can reach your server:

ansible all -i "server-ip-address," -u user -m ping

Breaking down this command:

• all tells Ansible to target all hosts
• -i "server-ip-address," specifies your server's IP (the comma is important for single hosts)
• -u user specifies the SSH username
• -m ping uses Ansible's ping module to test connectivity

If successful, you'll see output like:

server-ip-address | SUCCESS => {
    "ansible_facts": {
        "discovered_interpreter_python": "/usr/bin/python3"
    },
    "changed": false,
    "ping": "pong"
}

This confirms Ansible can connect to your server and execute commands.

Running System Commands

Try running a simple command on your remote server:

ansible all -i "server-ip-address," -u user -m shell -a "uptime"

This executes the uptime command and returns the results. You'll see how long the server has been running and its current load.

Creating Your First Inventory File

Typing server details in every command gets tedious quickly. Inventory files solve this by defining your servers in a reusable format.

Create a file called inventory.ini:

[webservers]
web1 ansible_host=192.168.1.10 ansible_user=ubuntu
web2 ansible_host=192.168.1.11 ansible_user=ubuntu

[databases]
db1 ansible_host=192.168.1.20 ansible_user=ubuntu

This inventory defines two groups: webservers with two hosts, and databases with one host. Each host has an alias (like web1) and connection details.

Now you can run commands against groups or individual hosts:

# Ping all servers
ansible all -i inventory.ini -m ping

# Ping only web servers
ansible webservers -i inventory.ini -m ping

# Ping a specific host
ansible web1 -i inventory.ini -m ping

Setting Up a Configuration File

Rather than specifying the inventory file every time, create an ansible.cfg file in your working directory:

[defaults]
inventory = inventory.ini
host_key_checking = False
remote_user = ubuntu

This configuration:

• Sets the default inventory file
• Disables SSH host key checking (useful for dynamic environments)
• Sets the default remote user

Now you can run simpler commands:

# These commands now work without specifying inventory or user
ansible all -m ping
ansible webservers -m shell -a "df -h"

Common Connection Issues

If you encounter problems, here are the most common solutions:

SSH Connection Refused

server-ip-address | UNREACHABLE! => {
    "changed": false,
    "msg": "Failed to connect to the host via ssh",
    "unreachable": true
}

Check that:

• The server IP address is correct
• SSH is running on the server (usually port 22)
• Your SSH key is properly configured
• Firewall rules allow SSH connections

Python Not Found

server-ip-address | FAILED! => {
    "changed": false,
    "module_stderr": "/bin/sh: 1: /usr/bin/python: not found",
    "msg": "The module failed to execute correctly"
}

Some modern Linux distributions don't include Python by default. Install it:

# On the remote server
sudo apt update && sudo apt install python3

# Or specify Python 3 in your inventory
web1 ansible_host=192.168.1.10 ansible_user=ubuntu ansible_python_interpreter=/usr/bin/python3

Permission Denied

If you need to run commands that require sudo access, add the --become flag:

ansible all -m shell -a "apt update" --become

Or configure sudo access in your inventory:

[webservers]
web1 ansible_host=192.168.1.10 ansible_user=ubuntu ansible_become=true

Next Steps

You now have Ansible installed and can connect to your servers. You've run ad-hoc commands and created basic inventory files. In the next section, we'll explore Ansible's fundamental concepts: modules, playbooks, and how they work together to automate complex tasks.

The foundation you've built here - proper SSH connectivity and inventory management - supports everything else you'll do with Ansible.

Happy configuring!