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So throughout this skill, what we've been effectively doing is testing

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different parts of our system,

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testing the memory, testing the CPU, that type of thing, as well as learning

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how to manipulate particular values.

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Now, what we can do also is to utilize a very particular Ansible module,

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which is really designed for testing purposes, and that is the assert module.

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So how about we go to the documentation and have a look at what this module

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actually does.

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So if you just happen to search for Ansible Assert and collect this top link
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So if you just happen to search for Ansible Assert and collect this top link

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right here,

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as you can see straight away, this module is part of Ansible Core,

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so you don't actually have to install it via Ansible Galaxy.

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And if you want to use it, you can specify the fully qualified collection name

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of Ansible.builtin.assert.

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Now if we just scroll on down a little bit here, we can see the synopsis.

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It says here that its whole purpose is to assert that given expressions are

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true with an optional custom message.

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So really, this is what we've been doing with respect to our test.

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We're testing it as something true or as something false, as this particular
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We're testing it as something true or as something false, as this particular

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number over this particular value,

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is that true or as that false, and then have a message.

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And this particular module we have this nice elegant way to specify within the

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same task,

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if a test happens to fail or if a test happens to pass.

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So if we scroll on down here, we can see we happen to have a parameter fail_msg

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.

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This is how we specify the custom message that we want to use when a failure

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happens.

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Conversely, if we scroll on down, we also have this other option,

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success_msg. This is the custom message that you specify when you have a
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success_msg. This is the custom message that you specify when you have a

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successful assertion i.e. when the test pass.

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Then if we scroll on down, we also have the that keyword.

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And as we can see here, this one is actually required.

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So the module cannot work unless you use this particular parameter.

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So realistically, if we scroll on down, we can see all of these additional

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examples right here.

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And feel free to copy them, paste them, try them out and see how you get on.

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But from now, let's write one of our own, which is really quite simple.

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So let's go back and we'll create a playbook called Play4.yml
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So let's go back and we'll create a playbook called Play4.yml

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and go into Incent Mode, have our three hyphens at the top, give the playbook a

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name,

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and I'll just say Play4, testing the asset module.

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So the host I'm going to target will be the all group, and again, we'll set

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gather_facts to false.

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We still don't need these facts.

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And then we will specify our task.

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Now the very first task is going to have a name.

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And let's just say, test whether a file exists.

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Now if you recall earlier on within this course, we happen to use the stat

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module.

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Again, this is built in, we don't have to install anything.
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Again, this is built in, we don't have to install anything.

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And pretty much, this is going to allow us to determine whether a file exists,

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as well as a whole bunch of other information, such as as the file directory,

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what is the size of the file that type of thing.

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So we can use this to perform a very simple test.

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Let's go back to our playbook then.

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And the module we will use will be Ansible.bilton.stat.

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Now in this case here, we're going to supply a particular path.

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So what I will do here is I'll go into my blue box.

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So let's go into the 10th directory, do an LS.

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If I just create a little file here, let's call this, or I don't know.
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If I just create a little file here, let's call this, or I don't know.

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Let's just say recipe.txt, go into insert mode, and we just add in some values,

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check in potatoes and veg.

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And crucially, we won't have this particular file over on the yellow box.

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So let's use Ansible to detect the presence of that file across our devices.

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So what I will do here is specify the path that I want to check.

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I will say forward slash TMP, and then it's going to be recipe.

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And I want to capture the output as a variables, let's just call this, recipe

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output.

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And now I'll have a new task with the name just specifying a set, whether the

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recipe file exists.
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recipe file exists.

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So to specify the Ansible built in a set module right here.

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Now remember, the required parameter is the keyword that.

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And now I want to grab my variable here.

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And because I have used the STAT module, if your recall, this is going to bind

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some

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particular attributes to the actual variable itself.

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So we can go into the STAT attribute and then we should also have an attribute

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known as

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exists.

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And now here very elegantly, we can specify our success message.

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And thank rotation marks, I'll just say the recipe.txt file exists on.
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And thank rotation marks, I'll just say the recipe.txt file exists on.

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And I'll specify my inventory host name.

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And I'll also have my failure message.

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So specify fail underscore MSG.

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And with the rotation marks, I'll say the recipe.txt file does not exist.

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And again, I'll pass in my inventory host name.

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So fairly simple test.

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And it is very readable.

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So if I go back to my terminal run my playbook of playbook 4.YML,

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we should see a result specifying that the blue box does have this fail,

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whereas the yellow box does not.
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whereas the yellow box does not.

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So let's try and hit enter.

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And the playbook runs now.

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Look at the output here.

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This is really, really handy.

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We get to see our message.

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And the case of the blue box here, it specifies the recipe.txt file exists in

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the blue box.

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But more interestingly, is that when we happen to have a failure,

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we then just print out a fail message.

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We actually instructed Ansible about a genuine failure.

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Look at this.

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Ansible reporting a failure.

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And in our play recap, we can actually see we've updated a failure right here.

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You see that one failure is present.

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This is also one of the advantages of using this particular module.
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This is also one of the advantages of using this particular module.

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As opposed to you just printing out a message saying, hey, the test field,

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and effectively it's not really updated in the Ansible output here.

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So by using the assert module, we get that update,

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and we get this nice clean way to specify whether a test passed,

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or whether in this case here a test happened to fail.

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So with all that said, let's now validate what we've learned within this scale.