If you are a network administrator you probably have dozens of devices to manage. Usually, each device is built by a manufacturer and although its administration may seem similar, it uses to be different.
For some tasks you will need to do several configurations in a group of devices that have different administration interfaces. This is a lot of work with a lot of possibilities of error.
Some manufacturers can provide a centralized platform to configure their equipment, but there is no one platform that could manage different devices for a single task that configure them all.
In this way, you have two alternatives:
- Do yourself. Develop your own platform that connect to your devices, update their configurations and report the result.
- Adapt an existing platform. There are some free software, but obviously you must configure and adapt them. We will take this way in this post.
Ansible’s web site describes itself like: “a radically simple IT automation platform that makes your applications and systems easier to deploy”.
Ansible is a software that has a collection of well described hosts, scripts, templates and variables, uses them for managing groups of hosts in a simple and automatic way and report the result of changes made in the hosts.
One of most common examples is update a config file of a web server farm and reload the web server daemon in all hosts of the farm. Ansible will connect to each host, change the config file, reload the daemon and report the result to the system administrator.
It's a powerful software, but not everything that shines is gold.
Unfortunately, Ansible is oriented to manage Linux hosts. More exactly, Ansible expects that remote hosts runs python.
Fortunately, you are a good network administrator that read good blogs and you can adapt Ansible to work with almost any device that can be administered by SSH, telnet or API.
The goal is to show how ansible can be configured for managing almost any network device. To do this we will need to build a module and use it. This module must connect to the network device in the way that you chose, and must report if the configurations had changed something in the remote device, if a problem had occurred, or if everything was fine.
For the example we will create a complete set of queues in a Mikrotik router. We will build a module that read a YAML file with the queues description, it connects to Mikrotik via API and adds all the queues to the router. This module will use API for configuring the Mikrotik in order to expose that any managing protocol supported by network devices can be used, but I have modules that manages routers and switches by SSH and Telnet.
As I comment before, this is not a manual about Ansible's installation. I guess that you can read Ansible documentation by yourself and you can install it without my help.
The first thing we need to do is to declare a host in Ansible's host file. We need to provide a user/password for API access (Only for this example that uses API, the best way is do this with a SSH key pair with no user/password).
[mikrotik]
192.168.150.1 username=ansible password=s0mEStr0ngP4ssw0rd
And a basic YAML playbook for testing the connection. We will use Roles. They aren't needed for this basic example, but it’s a good habit to order the information from the first steps.
# cat mktQueue.yml
---
- name: Test connection
hosts: 192.168.150.1
gather_facts: no
roles:
- mikrotik
By default Ansible will try to gather a lot of information from remote hosts, but it will use python for this. With “gather_facts: no” we ensure that Ansible will not recover this information.
# cat roles/mikrotik/tasks/main.yml
- name: Test connection
addqueues.py:
hostname: "{{ inventory_hostname }}"
username: "{{ username }}"
password: "{{ password }}"
delegate_to: 127.0.0.1
The line “delegate_to: 127.0.0.1” says to Ansible that module “addqueues.py” must be run locally (in the same host where Ansible is running) and not in remote devices.
# cat roles/mikrotik/library/addqueues.py
#! /usr/bin/python
import rosapi
import socket
from ansible.module_utils.basic import *
def main():
module = AnsibleModule(
argument_spec=dict(
hostname=dict(required=True),
username=dict(required=True),
password=dict(required=True),
)
)
hostname = module.params['hostname']
username = module.params['username']
password = module.params['password']
changed = False
msg = ""
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((hostname, 8728))
apiros = rosapi.RosAPI(s)
apiros.login(username, password)
module.exit_json(changed=False, msg=msg, username=username, password=password)
if __name__ == '__main__':
main()
I have used this python module:
https://pypi.python.org/pypi/rosapi to connect via API.
With this basic configuration we can test
Now the more interesting part of the post: build an Ansible module. This python module will read a YAML file placed in “files” directory of the role, it will build a Mikrotik queue tree configuration, it will connect to the Mikrotik router Via API and it will apply the configuration.
# cat roles/mikrotik/library/addqueues.py
#! /usr/bin/python
import sys
import string
import rosapi
import socket
from yaml import load, dump
try:
from yaml import CLoader as Loader, CDumper as Dumper
except ImportError:
from yaml import Loader, Dumper
from ansible.module_utils.basic import *
#
# Function ApplyQueue
# Connect to Mikrotik via API and apply all queues previously treated by processQueues
#
def applyQueue (hostname, username, password, queues):
returnValue ={'changed': False, 'error': ""}
error=None
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((hostname, 8728))
apiros = rosapi.RosAPI(s)
apiros.login(username, password)
for singleQueue in queues:
newQueue=[]
newQueue.append("/queue/tree/add")
for (param, value) in singleQueue.iteritems():
newQueue.append("=" + str(param) + "=" + str(value))
apiros.write_sentence(newQueue)
output=apiros.read_sentence()
if output[0] != "!done":
returnValue['error']=str(output[0]) + ": " + str(output[1] + " in \"" + singleQueue['name'] + "\"")
else:
returnValue['changed']=True
return returnValue
#
# function processQueues
# For a well formated dictionary of properties/values return an ordered array of dictionaries with
# a description of a queue and its children.
#
def processQueues( queues ):
newQueue={}
orderedQueues=[]
#
# In a first round search all properties/values of the queue.
#
for param, value in queues.iteritems():
if not isinstance(value, list):
#
# for property "comment", add a couple of colons
#
if param=="comment":
newQueue[param]="\""+value+"\""
else:
newQueue[param]=value
orderedQueues.append(newQueue)
#
# In second round search its children. Each child is treated as a new queue (recursive call)
#
for param, value in queues.iteritems():
if isinstance(value, list):
for subQueue in value:
subQueue['parent']=newQueue['name']
orderedQueues = orderedQueues + processQueues(subQueue)
return orderedQueues
def main():
module = AnsibleModule(
argument_spec=dict(
hostname=dict(required=True),
username=dict(required=True),
password=dict(required=True),
queuesFile=dict(required=True)
)
)
hostname = module.params['hostname']
username = module.params['username']
password = module.params['password']
queuesFile = module.params['queuesFile']
changed = False
queuesToApply = []
#
# Open the YAML file with queues configuration
#
yamlFile=open(queuesFile, 'r')
queues = load(yamlFile, Loader=Loader)
#
# for each queue in the YAML file process the queue (build it and its children, grandsons, etc.
# After all queues are processed, apply them.
#
for queue in queues:
queue['parent']="global"
queuesToApply = queuesToApply + processQueues(queue)
result=applyQueue (hostname, username, password, queuesToApply)
#
# return the result of the operation.
#
changed=result['changed']
if result['error']:
module.fail_json(changed=changed, msg=result['error'])
else :
module.exit_json(changed=changed, result=result['error'], username=username, password=password)
if __name__ == '__main__':
main()
For doing a tree example I will use the
tree configuration of Greg Sowell's blog. But I want to show a three-level tree structure, so I have configured two extra queues called “high-priority-in” and “high-priority-out” and I have put the queues VoIP and admin like children of the queues high-priority:
# cat roles/mikrotik/files/queuesDefinition.yml
- max-limit: 10M
name: in
parent: global
queue: default
children:
- limit-at: 3M
max-limit: 10M
name: http-in
packet-mark: http-in
priority: 4
queue: default
- limit-at: 4M
max-limit: 10M
name: streaming-video-in
packet-mark: streaming-video-in
priority: 3
queue: default
- limit-at: 500k
max-limit: 10M
name: gaming-in
packet-mark: games-in
priority: 2
queue: default
- max-limit: 10M
name: download-in
packet-mark: in
queue: default
- limit-at: 1M
max-limit: 10M
name: customer-servers-in
packet-mark: customer-servers-in
priority: 1
queue: default
- limit-at: 500k
max-limit: 10M
name: vpn-in
packet-mark: vpn-in
priority: 2
queue: default
- name: high-priority-in
priority: 1
queue: default
children:
- limit-at: 500k
max-limit: 10M
name: voip-in
packet-mark: voip-in
priority: 1
queue: default
- limit-at: 500k
max-limit: 10M
name: admin-in
packet-mark: admin-in
priority: 5
queue: default
- max-limit: 10M
name: out
parent: global
queue: default
children:
- max-limit: 10M
name: upload-out
packet-mark: out
queue: default
- name: high-priority-out
priority: 1
queue: default
children:
- limit-at: 1M
max-limit: 10M
name: customer-servers-out
packet-mark: customer-servers-out
priority: 6
queue: default
- limit-at: 500k
max-limit: 10M
name: voip-out
packet-mark: voip-out
priority: 1
queue: default
- limit-at: 500k
max-limit: 10M
name: admin-out
packet-mark: admin-out
priority: 3
queue: default
- limit-at: 500k
max-limit: 10M
name: gaming-out
packet-mark: games-out
priority: 2
queue: default
- limit-at: 3M
max-limit: 10M
name: http-out
packet-mark: http-out
priority: 4
queue: default
- limit-at: 4M
max-limit: 10M
name: streaming-video-out
packet-mark: streaming-video-out
priority: 3
queue: default
- limit-at: 500k
max-limit: 10M
name: vpn-out
packet-mark: vpn-out
priority: 2
queue: default
With this extra configurations we must update the “tasks” file:
# cat roles/mikrotik/tasks/main.yml
- name: Test"
addqueues.py:
hostname: "{{ inventory_hostname }}"
username: "{{ username }}"
password: "{{ password }}"
queuesFile: "{{ playbook_dir }}/roles/mikrotik/files/queuesDefinition.yml"
delegate_to: 127.0.0.1
And finally, we can run it:
An error will show something like this:
Obviously, nobody needs an Ansible configuration to apply a dozen of queues. It has no sense doing so much work for a task that probably you don't need to repeat anymore. But this is only an example of how Ansible can manage network devices in a centralized way.
Some more interesting cases can be:
- A module that connect to Mikrotik, create a Mikrotik script from a template placed in the host that runs Ansible, run it on Mikrotik devices and return the result. This module can be a good method to update any general configuration in any number of Mikrotik devices in your network (for example, update your syslog server). If you build this module, the next time that you need to do a task in all your Mikrotik devices the only thing you must do is the Mikrotik script. Applying it in all network will be easy.
- A group of roles with its own modules that connect to groups Mikrotik, cisco and switches and configure some specific services that needs changes in these devices.
