Network Automation with Ansible:

Overview of Ansible:

An IT automation tool designed for performing actions (tasks) on multiple servers/devices. Ansible is extensivly used for automating configurations build, and has become one of the de-facto tools in the industry for autmating IT.
Agent-less: Ansible use SSH (quite native). There is no agent to install on the remote hosts, which is easisier, more secured because there are no additional ports to open.
Push-based approach: As soon as you run the ansible-playbook command (to execute a playbook), Ansible connects to the remote servers/devices and does its thing. Different from the pull-based approch often assicated with the tools relying on agents.
Some level of abstraction: The tool follows a declarative approach. You describe the desirated state, indicating "what", not "how“.

Ansible components:

Inventory file
Variables (YAML)
Tasks / modules (Python)
Plays and Playbooks (YAML)
- A playbook is a list of plays (from a code perspective it is a list of dictionaries).
- Playbook runs top to bottom.
- A play maps a selection of hosts to tasks. Each task is a call to an Ansible module, a small piece of code (written in python) for doing a specific task. Each task is associated with exactly one module.
- Tasks are executed in order, one at a time, against the selection of hosts, before moving on to the next task.
- A play associates an unordered set of hosts with an ordered list of task.

Network modules:

http://docs.ansible.com/ansible/list_of_network_modules.htm

Getting Started with Junos modules:

Pre-requisistes:

Those examples are performed with Ansible version 2.2.0.0
Install dependency (Vendor python library):
```
pip install junos-eznc
```
Configure Netconf on the network devices.

Example 1: configure BGP between two routers.

Populate the addresses of the Juniper routers:
- hosts file, located at the root of this repository.
Provide the credentials information to reach the devices:
- credentials.yml file, located at \group_vars\vmx
Prepare the Jinja2 files for the template module to use them:
- bgp.j2 file, located in the plabook directorty: \junos_template
Provide the variables information, to be used in the Jinja2 tempalting to render the configurations:
- bgp.yaml file, located in \host_vars\vmx1
- bgp.yaml file, located in \host_vars\vmx2
Write the playbook:
- pb.bgp.2.yml file, located at \junos_template\
- This playbook has 3 plays:
  - create BGP junos configuration, composed of 2 tasks.
  - wait for peers to establish connections, composed of 1 task.
  - check bgp states, composed of 1 task.

Run the playbook (First run):


mab@mab-infra:~/automation/ansible/junos_template$ sudo ansible-playbook pb.bgp.2.yml 
[DEPRECATION WARNING]: junos_template is kept for backwards compatibility but usage is discouraged. The module documentation details 
page may explain more about this rationale..
This feature will be removed in a future release. Deprecation warnings can be disabled 
by setting deprecation_warnings=False in ansible.cfg.

PLAY [create BGP junos configuration] **

TASK [Render BGP configuration for junos devices] ** ok: [vmx1] ok: [vmx2]

TASK [push bgp configuration on devices] *** changed: [vmx1] changed: [vmx2]

PLAY [wait for peers to establish connections] *****

TASK [pause] *** Pausing for 25 seconds (ctrl+C then 'C' = continue early, ctrl+C then 'A' = abort) ok: [localhost]

PLAY [check bgp states] ****

TASK [check bgp peers states] ** ok: [vmx2] => (item={u'interface': u'ge-0/0/0', u'local_ip': u'172.16.0.40', u'asn': 101, u'name': u'to vmx1', u'peer_ip': u'172.16.0.30'}) ok: [vmx1] => (item={u'interface': u'ge-0/0/0', u'local_ip': u'172.16.0.30', u'asn': 102, u'name': u'to vmx2', u'peer_ip': u'172.16.0.40'})

PLAY RECAP ***** localhost : ok=1 changed=0 unreachable=0 failed=0
vmx1 : ok=3 changed=1 unreachable=0 failed=0
vmx2 : ok=3 changed=1 unreachable=0 failed=0


- Run the playbook again (second run, to check idempotency):

mab@mab-infra:~/automation/ansible/junos_template$ sudo ansible-playbook pb.bgp.2.yml [DEPRECATION WARNING]: junos_template is kept for backwards compatibility but usage is discouraged. The module documentation details page may explain more about this rationale.. This feature will be removed in a future release. Deprecation warnings can be disabled by setting deprecation_warnings=False in ansible.cfg.