perform more advanced tasks such as continuous
deployments and zero-downtime upgrades. It was
created in 2012 and acquired by RedHat in 2015. Ansible
is appropriate for both small and large environments and
can be used for managing a handful of servers and
network devices or for managing thousands of devices. It
is agentless, meaning there is no software or service that
needs to be installed on the managed device. Ansible
connects to managed devices just as a regular system or
network administrator would connect for management
purposes—in most cases over SSH, but NETCONF and
REST API interfaces are also supported. Ansible is open
source and was developed using Python. There is also a
commercial offering available, called Ansible Tower,
which includes a web user interface, a northbound REST
API, role-based access control, statistics, and much
more.
Several Ansible concepts need to be discussed before we
go further:
Control node: The control node is any machine that has Ansible
installed. All flavors of Linux and BSD operating systems are supported
for the control node. Any computer, laptop, virtual machine, or server
with Python installed can be an Ansible control node. The exception to
this rule is that Microsoft Windows machines currently cannot be used
as control nodes. Multiple control nodes can run at the same time in the
same environment. It is a best practice to place the control nodes close
to the systems that are being managed by Ansible to avoid network
delays.
Managed node: The managed nodes in the Ansible taxonomy are the
network devices or servers that are being managed by Ansible. They are
also called hosts and do not need to have Ansible installed on them or
even Python, as discussed later in this chapter.
Task: Ansible tasks are the units of action. You can run them as ad hoc
commands by invoking them as follows:
Click here to view code image
$ ansible [pattern] -m [module] -a "[module
options]"