Getting Started with Ansible
Ansible doesn’t have a steep learning curve and it doesn’t require any sort of programming background to use. You can begin running commands against your network inventory in no time at all. And I can prove it!
This is all using network devices as examples, but it’s all general Ansible stuff that we’ll be doing. This next section will overview how to start using Ansible. Download and install it, make an inventory, and then run a playbook against your network — in less than five minutes!
Step One: Installing Ansible and Git
Along with Ansible. we’ll be using Git. Git is a version control system. We will use it as a code repository for storing and controlling access to our network automation playbooks.
Fedora dnf install ansible git CentOS/RHEL yum install ansible git Mac/PIP pip install ansible Ubuntu apt update apt install software-properties-common apt-add-repository --yes --update ppa:ansible/ansible apt install ansible apt install git
After installation, verify that you can run Ansible:
Full download/install instructions can be found here:
Step Two: Create an Inventory
Now that we have Ansible installed, let’s create our inventory that Ansible will use to connect to our hosts. To keep it simple, let’s just start with a small INI file, and a few test devices with the OS they’re running and the user/pass we’ll need to login.
In the host file you create, you’ll have one inventory host per line that defines these variables needed for Ansible to run.
1. ansible_hostname = hostname_fqdn 2. ansible_network_os = ios/nxos 3. ansible_username = username 4. ansible_password = password
Name this file
[all] hostname_fqdn ansible_network_os=ios ansible_username=<username> ansible_password=<password> hostname_fqdn ansible_network_os=nxos ansible_username=<username> ansible_password=<password>
We’ll make a better inventory later. For now, this is as simple as it gets, and this will allow us to immediately begin connecting to and managing our network devices. With Ansible installed, and with our inventory setup with the username, password, and host OS, we’re ready to run something!
The full list of network OS’ can be found here: https://github.com/ansible/ansible/blob/devel/docs/docsite/rst/network/user_guide/platform_index.rst
Verify: Ansible Installed; Inventory Created; Repo Ready
At this point you, you should be able to run Ansible, and you should have an inventory file. Verify that you have both:
ansible --version file inventory
Now, we need something to run! Since our goal is to begin managing our network devices, then the perfect place to start is at Fact Collection.
In Ansible, facts are useful variables about remote hosts that can be used in playbooks. And variables are how you deal with differences between systems. Facts are information derived from speaking with remote devices/systems.
An example of this might be the IP address of the remote device, or perhaps an interface status or the device model number. Regardless, this means that we can run any command, save that output as a fact, and do something with it…
For instance, we can run a command like
show version, and use the output to identify the firmware version. Beyond that, the possibilities are limitless! We can use any device information we can get our hands on.
Step Three: Run a Playbook
To get us started with fact collection, here’s a Git repo with my Ansible playbooks I use to gather facts and configs on all of my random network devices:
Before we can use it, we need to clone this repo somewhere for Ansible to run it:
This will create a directory called
facts-machine. Within that repo, I have my Ansible config (
ansible.cfg) set to look for either an inventory file or directory called “inventory.” Keep it simple.
Move your inventory into this that directory, and run the fact collection playbook!
cp inventory facts-machine ansible-playbook -i inventory facts.yml
This will run a playbook that will gather device info — and the full running config for every device in your inventory. This role will connect to these devices:
ansible_network_os: eos ios iosxr nxos aruba aireos f5-os fortimgr unos paloalto vyos
Every Config…from Every Device!
In one felt swoop, you suddenly have a backup of every network config…from every device! Ansible Facts will be available at the end of the playbook run.
ansible_facts: ansible_net_api: cliconf ansible_net_fqdn: rtr1 ansible_net_gather_subset: - all ansible_net_hostname: rtr1 ansible_net_image: flash:EOS.swi ansible_net_model: vEOS ansible_net_python_version: 2.7.5 ansible_net_serialnum: D00E130991A37B49F970714D8CCF7FCB ansible_net_system: eos ansible_net_version: 4.22.0F ansible_network_resources: interfaces: - enabled: true name: Ethernet1 mtu: 1476 - enabled: true name: Loopback0 Etc… etc… etc…