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So friends, now that we have an idea of how to create our host variables,

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let's now dive in to the intricacies of creating our group variables.

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Now we already mentioned that with respect to the host files, we would have to

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create a directory called host_vars

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and for the creation of group variables, we will have to specify a group_vars

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directory.

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Now inside of this directory, we're once again going to create files with the .

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YML extension

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and the name of the files, this time as opposed to correlating to the name of
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and the name of the files, this time as opposed to correlating to the name of

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the individual host in the inventory,

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we're going to correlate to all of the groups within the inventory.

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Now right now, the only group we have is the all group, so we're going to have

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a file called all.yaml,

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but if in the inventory, perhaps you may be creating a USA group.

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Once again, inside of the group_vars directory, you could create a USA.YML file

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as well.

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So in the inventory, if we go in, like I say, we could create this USA

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and maybe see the blue box in the USA.

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By virtue of this being present here within the square brackets in the INI
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By virtue of this being present here within the square brackets in the INI

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format,

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Ansible will look for a USA.YML file within the group_vars directory.

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This is how this is going to operate.

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So for now, what I will do is I will just delete this because we don't actually

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need this right now.

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Let's just leave the all group.

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And the first thing I really want to highlight here about the group variables

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is that we have to understand the order of priority here.

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Now by default, Ansible is going to look for an all group that's going to

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comprise of all of the hosts in the inventory.

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We have defined this in our inventory already.

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And this particular group with this naming convention all is at the lowest
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And this particular group with this naming convention all is at the lowest

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priority.

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Basically, because it is the widest group, it includes all of the devices

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within the inventory.

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This is the least specific group.

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To help you understand this concept, let's actually consult the Ansible

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documentation.

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If you just happened to search for organizing host and group_vars, let's go to

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this particular link,

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how to build your inventory.

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And if we just scroll on down, check this part right here.

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We're talking about how variables happen to be merged.
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Now right now, this is going to be the order of operation.

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Pretty much we're looking at the lowest priority all the way to the highest

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priority.

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The way to remember this is that the more specific a variable is the higher the

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priority is.

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What do I mean by say that we'll think about it in some cases, you may have

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variables defined

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at different levels within the inventory.

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So let's maybe say in the all.yaml file, you happen to have the test for key.

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Well, who's that going to apply to?

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It's going to apply to all of the devices in the inventory because that is what
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It's going to apply to all of the devices in the inventory because that is what

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the all group is.

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Whereas if you happen to define the same variable, test for in this case, in a

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general parent group,

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this will actually override the value for all devices in that group as opposed

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to those devices

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getting that value as defined in the all.yaml file.

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Similarly, moving on down, if we happen to have a child group of a particular

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parent,

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if the same variable is defined there, once again, test for any members of the

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child group
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is going to get that particular variable value overriding what was defined in

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the parent.

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As I say, as we get more and more specific, we have a higher priority.

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And at the highest level of priority, if there is a clash between any of the

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group variables

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and a particular host variable, if that variable is defined at the host level,

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once again,

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such as test for the device will take the value as defined in its host variable

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file

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because it is the most specific.

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Now right now, because we have a very, very simple inventory, we just have one

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group called all.
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group called all.

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Let's look at the answerable documentation to see information whereby we have a

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more detailed inventory.

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So let's just scroll up here.

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Here we can see an inventory in yaml format, which is absolutely valid.

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And above, we can also see the same inventory as specified in i and i.

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So let's imagine for now, within our all.yaml file, we simply had a variable

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simply defined as DNS_server, okay?

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And the value of that was 1.1.1.1.

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Now, virtue of this being in the all group, this means if we happen to
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Now, virtue of this being in the all group, this means if we happen to

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reference the double-color braces

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with the DNS server variable, every device in the inventory is going to get the

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value 1.1.1

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when it comes to a DNS server.

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However, some devices here say, for example, in the Atlanta group, this is

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going to comprise of host 1 and host 2.

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Let's say in the Atlanta.yaml file, we have the exact same variable to find,

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DNS_server,

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but the value here is 2.2.2.2.
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That means the devices host 1 and host 2, when it comes to render their

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variable value,

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they are not going to get all the ones, they are going to get all the tools,

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and all the other devices will still get 1.1.1.1.1.

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Now, let's maybe say that host 2, however, within the host var directory,

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inside of the host 2.yaml file,

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if that actually has the same key defined once again, DNS_server, with the

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value 3.3.3.3.3,
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this particular host is going to get the 3.3.3 value because its host variable

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value will override its group membership.

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Now, one last thing to say, in fact, let's just look at this in the yaml format

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because it is actually easier to look at in terms of visually,

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when I'm talking about a parent group versus a child group.

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As we can see here, we have a USA group, an example here, and we have a child

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group called Southeast,

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as well as Northeast, Northwest, and Southwest.

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Basically, if there's a clash between the files in Southeast versus the USA,

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Southeast is a child,
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Southeast is a child,

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so the Southeast.yaml file, the value in that particular file is going to

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override the USA.yaml file.

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Going further again, if the same variable is defined in, say, for example,

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rally.yaml,

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we can see rally is indeed a child of Southeast, so rally would override

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Southeast as well.

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Therefore, the host belonging to this particular group, in this case here, host

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to and host 3,

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they would get the value from rally.yaml unless, like I say, they happen to
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they would get the value from rally.yaml unless, like I say, they happen to

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have it defined personally in their own host variable file.

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That is the order of operation.

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Now, we can see here, in this case here, we have Atlanta and rally, and they're

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both at the same indentation level.

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One is not a child of the other.

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Now, in this case here, we actually don't have any hosts that belong to both of

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these groups,

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but you can conceptualize a world, in which case a device belongs to multiple

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groups at the same indentation level.

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The way Ansible is going to resolve this behavior is it's going to effectively

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flatten and merge these files,
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flatten and merge these files,

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and it's going to do this on the basis of ASCII order with the last group

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winning.

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So, let's imagine we have a group called a group, and another group called a

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group.

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They are at the same level of indentation, and in the group-vars directory, we

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're going to have an a-group.yaml file,

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as well as a b-group.yaml file.

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If we have a clash, which one is going to win, well, because the b-group will

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be processed last, because of alphabetical order,

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the b-group here is actually going to take priority.

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That is how we're going to resolve any of these potential clashes.
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That is how we're going to resolve any of these potential clashes.

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But for now, let's get hands on and begin creating some group variables.

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So, what we're going to do, I'm going to create this directory called group_v

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ars,

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let's just cdin, and all I'm going to do is create a file named after every

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group in our inventory,

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which in this case here is only the all group, so we have all dot.yaml.

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So, let's go in here.

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Let's have a variable called dnsserver, and I will just give this the address

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of 8.8.8.8,

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and if I go back and I just copy my var playbook, and I'll just call this var
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and if I go back and I just copy my var playbook, and I'll just call this var

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play2.yaml,

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and if we go in and edit this particular playbook, all I'm going to do is I'm

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going to echo in

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the dnsserver variable, and I'll write it into a file called dnstest.ok.

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So, right now, if I run this particular playbook, and to enter, we can see we

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have a change

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on both of our devices, let's go and test.

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So, we're in the 10th directory, if I do an LS, we can see we have this dnstest

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file,

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if I cat open the file, and to enter, we can see the value for blue box is 8.8.

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8.

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It got that value because of its membership to the all group, and thus took the
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It got that value because of its membership to the all group, and thus took the

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value directly

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from the all dot.yaml file when we called the variable.

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Similarly, no surprises when we go to the yellow box.

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As we can see, the file is also here, let's just cat open.

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Once again, we get the exact same value, now the interest and thing, like I say

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, if we happen to have a clash,

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and let's go into the host var directory, say for example, and let's maybe go

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into the yellow box.

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Okay. So, what I'm going to do is, inside of here, I'm going to have the exact

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same key dns_server,

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but I'm going to give it a completely different value.
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Let's go with 2.2.2.2.2. Okay.

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So, let's write this out. We can see when it comes to yellow box, we have 2.2.2

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.2, but it also has membership to the all group,

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which specifies the variable should be 8.8.8.8.

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As you should suspect, when it comes to this clash, which key is going to be

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called for that particular device,

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the more specific value is going to win, thus we should actually see.

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For the yellow box, the value should change to 2.2.2.2.2.

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So, let's go and check that out, then let's go back, clear the stream.

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We will rerun the same playbook, this time with the updated var files.
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We will rerun the same playbook, this time with the updated var files.

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As we can see, we have written the change.

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We go to the blue box, cat dns_test, no surprises there, it still gets 8.8.8.

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However, when we go over to the yellow box and we cat this file again, notice

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it now gets 2.2.2.2.2.

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This here is an example of the inheritance model prioritizing the variable with

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the more specific value.