Red Hat Ansible for Network Automation
After completing this section, you should be able to:
Create a simple playbook.
Check playbook syntax with
ansible-playbook --syntax-check.
A task is the application of a module to perform a specific unit of work. An example of a task in a play is shown below.
tasks:
- name: Backup configuration
ios_config:
backup: yesA play is a sequence of tasks to be applied, in order, to one or more hosts, whereas a playbook is a YAML file containing one or more plays.
An example of a play in a playbook is shown below.
---
- name: backup router configurations
hosts: routers
connection: network_cli
gather_facts: no
tasks:
- name: gather ios_facts
ios_facts:
register: version
- debug:
msg: "{{version}}"
- name: Backup configuration
ios_config:
backup: yesYAML is a human-friendly language that concisely represents objects as data. Additional characteristics of YAML include:
Files start with three dashes (---) that mark the start of the document.
Comments begin with the pound sign (#).
Indentation is significant, and spaces must be used rather than tabs.
Elements at the same level (items in the same list, for instance) must have the same indentation.
Children of an item are indented more than the parent.
Unquoted scalar
Network
Sequence of scalars
- 10.0.0.1 - 192.168.0.1 - 172.16.0.1
Mapping scalars to scalars
IPv4: 10.10.17.42/24 IPv6: "fd42:e5a1:ef5d:6030:0:0:0:2/64"
Mapping scalars to sequences
rtr01: - GigabitEthernet1 - GigabitEthernet2 rtr02: - eth0 - eth1
Sequence of mappings
- name: GigabitEthernet2 ipv4: 172.16.2.2/30 ipv6: "fd42:e5a1:ef5d:6030:0:0:0:2/64" - name: eth1 ipv4: 10.10.10.1/30 ipv6: "fdbc:bda:8486:7118:0:0:0:1/64"
Mapping of mappings
vyos: ansible_network_os: vyos ansible_user: vyos ios: ansible_network_os: ios ansible_user: admin
Sequence of scalars
[ GigabitEthernet1, GigabitEthernet2, GigabitEthernet3 ]
Mapping scalars to scalars
{ name: eth1, ipv4: 10.10.5.1/30, ipv6: "fdb5:4b4e:4574:c6bb:0:0:0:1/64" }Sequence of sequences
- [name, ipv4, ipv6] - [GigabitEthernet1, 172.16.2.2/30, "fdb5:4b4e:4574:c6bb:0:0:0:1/64"] - [GigabitEthernet2, 10.10.5.2/30, "fdb5:4b4e:4574:c6bb:0:0:0:2/64"]
Sequence of mappings
- { name: GigabitEthernet2, ipv4: 172.16.2.2/30 }
- { name: GigabitEthernet4, ipv4: 172.16.10.1/30 }Mapping of mappings
GigabitEthernet1: {ipv4: 10.0.0.1/30, ipv6: "fdb5:4b4e:4574:c6bb::1/64"}
GigabitEthernet2: {
ipv4: 192.168.5.1/30,
ipv6: "fdea:230f:c3cf:c287:0:0:0:1/64"
}How are Ansible plays encoded in YAML?
A playbook is a list of one or more plays.
Each play is a hash/dictionary; that is to say, a YAML sequence of
key:valuemappings.A play must include
hostandtasksmappings, and may include anamemapping, as well as other mappings depending on which plug-ins are being used.Plays can import or include files, other playbooks, task lists, and so on.
Which key:value pairs are used to define plays in playbooks?
Plays can be named or anonymous. It is useful to name your plays. For example,
name:playname. Ideally, a name communicates clearly the purpose of a play.Plays take a list of tasks and apply them to a list of hosts or host groups.
---
- name: a play that backs up configs
hosts:
- routers
tasks:
- name: backup the running config
ios_config:
backup: yesA trivial test module that always returns pong on successful contact.
This is not an ICMP ping, and requires Python on the remote node.
It usually does not make sense in playbooks, but is useful from
/usr/bin/ansibleto verify the ability to log in and that a usable Python is configured.
Tests reachability by pinging from an IOS network device to a remote destination.
[user@host ~]$ansible -m ios_pinghost-identifier-a "dest=ip-address"
