WEBVTT

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In this lecture,

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we will get introduced
to Infrastructure as Code,

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which is commonly known as IAC.

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We will also take a look
at commonly used IAC tools.

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Earlier,
we discussed about provisioning

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by making use
of the management console

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of various cloud providers.

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The better way
to provision cloud infrastructure

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is to codify
the entire provisioning process.

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This way
we can write and execute code,

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to define, provision,
configure, update,

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and eventually
destroy infrastructure resources.

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This is called
as Infrastructure as Code or IAC.

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With Infrastructure as Code,

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you can manage
nearly any infrastructure component

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as code,

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such as databases, networks, storage,
or even application configuration.

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The code you see here
is a shell script.

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However, it is not easy to manage it.

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It requires
programming or development skills

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to build and maintain.

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There's a lot of logic
that you will need to code,

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and it is not easily reusable.

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That's where tools

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like Terraform and Ansible
help with code

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that is easy to learn,
is human readable and maintain.

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A large shell script
can now be converted

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into a simple
Terraform configuration file

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like this.

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With Infrastructure as Code,

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we can define
infrastructure resources

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using simple, human readable
high-level language.

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Here is another example

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where we will be making use
of Ansible

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to provision three AWS EC2 instances,

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making use of a specific AMI.

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Although Ansible and Terraform
are IAC tools,

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they have some key differences
in what they are trying to achieve,

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and as a result,

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they have
some very different use cases.

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Here,
we'll see these differences next.

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There are
several different tools part

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of the Infrastructure as Code family;

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Ansible, Terraform, Puppet,

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CloudFormation, Packer, SaltStack,

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Vagrant, Docker, et cetera.

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Although you can possibly
make use of any of these tools

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to design similar solutions,

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they have all been created
to address a very specific goal.

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With that in mind,

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IAC can be broadly classified
into three types;

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configuration management:

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Ansible, Puppet, SaltStack
fall into this category.

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Tools used for server templating;

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Docker, Packer, and Vagrant
fall into this category.

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Finally, we have
infrastructure provisioning tools,

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such as Terraform and CloudFormation.

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Let's look at these
in a bit more detail.

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The first type of IAC tool
that we are going to take a look at

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is configuration management tools.

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These include tools

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like Ansible, Chef, Puppet,
and SaltStack,

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and these are commonly used
to install and manage software

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on existing infrastructure resources

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such as servers, databases,
networking devices, et cetera.

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Unlike the ad-hoc shelf scripts
that we saw earlier,

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configuration management tools
maintain

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a consistent and a standard
structure of code,

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and this makes it easier
to manage and update it as needed.

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They are also designed to run
on multiple remote resources at once.

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An Ansible playbook or a role
can be checked

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into a version control repository.

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This allows us
to reuse and distribut it as needed.

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However,

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perhaps the most important feature
of a configuration management tool

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is that they are idempotent.

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This means that you can run the code
multiple times

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and every time you run it,

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it will only make changes
that are necessary

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to bring the environment
into a defined state.

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It would leave anything
already in place as it is,

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without us having to write
any additional code.

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Next,

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let's look
at server templating tools.

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These are tools

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like Docker, Vagrant,
and Packer from HashiCorp

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that can be used to create

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a custom image
of a virtual machine or a container.

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These images already contain

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all the required software
and dependencies installed on them,

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and for the most part,

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this eliminates the need
of installing software

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after a VM or a container
is deployed.

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The most common examples
for server templated images

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are VM images

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such as those
that are offered on osboxes.org,

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custom AMIs in Amazon AWS,

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and Docker images on DockerHub
and other container registries.

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Server templating tools
also promote immutable infrastructure

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unlike
configuration management tools.

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This means that,

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once the VM or a container
is deployed,

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it is designed to remain unchanged.

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If there are changes to be made
to the image,

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instead of updating
the running instance,

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like in the case
of configuration management tools

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such as Ansible,

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we update the image
and then re-deploy a new instance

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using the updated image.

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We have a section
on immutable infrastructure

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later in this course

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where we will look at it
in much more detail.

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The last type of IAC tool

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which is specifically
of interest for this course

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is provisioning tools.

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These tools are used to provision
infrastructure components

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using a simple declarative code.

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These infrastructure components
can range from servers

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such virtual machines, databases,
VPCs, subnets,

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security groups, storage,

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and just about any services
based on the provider we choose.

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While CloudFormation
is specifically used

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to deploy services in AWS,

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Terraform is vendor agnostic

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and supports provider plugins
for almost all major cloud providers.

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In the upcoming lecture,

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we will see how Terraform helps
in provisioning infrastructure.