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Okay friends, so how about we get hands on and begin by first talking about

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host variables.

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So no surprises when we're talking about host variables, we're just talking

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about defining

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those variable values at the host level. That means the individual hosts within

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our inventory,

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we know we happen to have a blue box, as well as a yellow box device in our

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inventory.

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So by specifying host variables for yellow box, they will only apply to this

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device,

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and conversely any host variables assigned to blue box will only apply to blue
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and conversely any host variables assigned to blue box will only apply to blue

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box.

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That is the whole goal here. Now just to be very clear here, host variables can

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actually be defined

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within the answerable inventory themselves, basically within the actual INI

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file that we use to

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specify or manage devices, or if you happen to be using the YAML format, the Y

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AML format of the

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inventory. Now the key thing to note here is that whilst many years ago this

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was very, very common,

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now this is a deprecated practice and it is really not recommended. As we're

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going to learn,

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a much better way to handle this process is to have designated files for these
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a much better way to handle this process is to have designated files for these

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host variables as

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opposed to bundling them in with the rest of the inventory information. The

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reason why is that

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this keeps things less cluttered and much better organized. Now as we're also

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going to learn,

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and we'll talk about in the next video, we can also have something known as

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group variables.

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You can imagine what these are going to do, it's going to be the same type of

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thing, it's going to

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allow us to assign variables but not at a host level but rather the group that

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the host belongs to.

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Now as we're going to learn when we're defining these particular files for
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Now as we're going to learn when we're defining these particular files for

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hosts,

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they're going to have to be specified in the YAML format and the exact same is

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true for our group

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variables. Quite simply for our host, we're actually going to have a very

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particular directory

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known as host_verse. This is a directory that we'll have to create on our own

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Linux

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system but by virtue of it being present in the working directory where we

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happen to be

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managing Ansible, the Ansible system is going to automatically seek to find

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this

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particular directory. So make sure that we do actually have this particular
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particular directory. So make sure that we do actually have this particular

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name Ansible,

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it's actually looking for this as a convention. Now inside of this particular

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directory,

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we're going to have a whole bunch of YAML files like I said, that's going to be

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the format.

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And we're actually going to name each file after the device name within the

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inventory. So we know

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we have a device in the inventory called Bluebox, so we'll have a Bluebox.YAML

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file and we're also

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going to have a yellowbox.YAML file, both of which, like I said, within the

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host_verse directory

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and Ansible is going to be able to figure out that the information in this
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and Ansible is going to be able to figure out that the information in this

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particular file

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should correspond to the device which has the IP address correlating to the

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yellowbox name

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and similarly the same thing should happen for Bluebox. Ansible is going to

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handle all of this

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really, really handy. So let's go and create this directory structure then. So

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this here is my current

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directory, we can see this is where my Ansible inventory is, the configuration

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file where the

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playbooks are going to be running from. So within here, I'm just going to say

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mkdir host_verse.

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Now like I said in my inventory, here are the actual devices. So inside of host
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Now like I said in my inventory, here are the actual devices. So inside of host

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_verse, what I'm

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going to do is I'm going to create a file called Bluebox.YAML as well as yellow

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box.YAML. Perfect

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if I've done ls, here we are right here. Now we're going to have to populate

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these particular files

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with the values that we want. So let's try this and let's go into Bluebox first

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and I'll go into

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insert mode and have my three hyphens at the top. And all I'm going to do is

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just like we talked

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about in the previous scale, we have these key value pairs. This is exactly
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about in the previous scale, we have these key value pairs. This is exactly

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what I'm going to do.

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So the name of the key that I choose to define here can be anything I so wish,

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but that is going to be the variable that is referenced within the actual

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playbook.

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Let me just call this test var okay. Doesn't actually matter. So long as we put

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a column,

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we make it a key. And now within here, all I'm going to do is say bluebox and

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inside of the

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brackets, I'm going to give the IP address of the bluebox, which is 134, I

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believe it ends in.

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We just double check that. I'll open up a new terminal, let's just say cat, it
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We just double check that. I'll open up a new terminal, let's just say cat, it

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's say hosts.

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Yep, bluebox has that IP address here and we'll also do the same for yellowbox.

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So let's just

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write this out. And if we go into yellowbox, the key thing here though, is we

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want to be using the

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same key as a variable name. So we'll call this test var once again. The only

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difference is we're

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going to have a different value that is referenced. So this thing I will say

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yellowbox and into the

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brackets, I'll say 192, 168, 160 dot 135. So basically, if we happen to

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reference the name

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test var, we actually access a key for the yellow box that will render this
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test var, we actually access a key for the yellow box that will render this

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particular value. Whereas

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by calling the exact same key, this time for the blue box, the value is going

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to be rendered as

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blue box and then the blue box IP address. So let's tag together by creating a

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little playbook here.

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Let's go back a directory, turn LS and let's just create a playbook just called

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, let's just say

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var play call anything. So which one's a game? So we're going to insert more

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tavern, three

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hyphens at the top and I'll just give this play a name, just say playbook for

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testing hosts first.

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The host I'm going to target is going to be the all group, which means both
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The host I'm going to target is going to be the all group, which means both

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devices are going to be

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targeted here. I will have my tasks here defined. This is going to be an array

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object. So we start

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with her hyphen and then the name of this task, just say rights info to a file.

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Now, all I'm going to

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do here is I'm going to use the answerable built in shell module. So what I

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will do here is I will

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say echo. So I could say something like say hello there and redirect that into

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a file. Let's

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maybe say in the 10th directory, and we'll just call the file var test dot txt.

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The problem here

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is that for every device for targeting that is the all group, both boxes are
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is that for every device for targeting that is the all group, both boxes are

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going to get the exact

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same content here. Now, what if I wanted to have different content written into

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the file

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dependent on the actual device for targeting the way we do this, as you guessed

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it, we use a variable

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value. So what I can do here is as opposed to hard coding some type of value,

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what I'm going to do

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is use my double curly braces. Okay, now inside of here, what I'm going to do

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is just give the name

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of the actual variable. And the name itself is going to be test var. So if I

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just say test var

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right here, when we execute for blue box, we call in the variable within the
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right here, when we execute for blue box, we call in the variable within the

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blue box host var file,

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which is test var rendering this value. And when we're executing for yellow box

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, we'll look into

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host yellow box dot yml, grab the test var variable, and we render this

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particular value a different

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value entirely. So let's see if actually it works then. So I'll press writing

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quits, and all I will

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say is answerable playbook var play and to enter, and we can see our task right

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info to a file,

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we have two changes, both of which happen to be successful. So let's go to the
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we have two changes, both of which happen to be successful. So let's go to the

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device here.

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So we're on blue box, let's go into the temp directory, do an LS. Here we can

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see the vertex

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file. If I happen to cat vertex, look at the actual information we've written

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in here,

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blue box, and then the IP address. However, if I go to my yellow box here, cd

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into temp,

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do an LS, there is a fail var test. Let's cat that fail and look at this right

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here, we have a

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completely different value that has been populated using answerable. So now

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that we've seen how to

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use host variables, let's dig our teeth into the creation of group variables.
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use host variables, let's dig our teeth into the creation of group variables.