Narrator: Finally, we are going to talk about
the conditions.
So conditions are used to control the creation
of resources, or outputs based on some statements.
Logical statements.
The conditions can be whatever you want them to be,
but the common ones are that, maybe you want to say,
if you're in dev, or if you're in test,
or if you're in prod create or don't create that resource.
Maybe it can be based on the region,
maybe based on the parameter value.
Each condition can reference another condition,
parameter value or mapping, so you can compose them.
So to define them, to make it a little more concrete,
here is a condition that I've created
under the block conditions.
Here we say, okay, do we want to create
the production resources?
For this, you need to have the environment type,
and that may be a parameter.
This environment type right here.
We need to have the reference,
so the value of this paramater to be equal to prod,
P-R-O-D, the string prod.
So here, basically, this whole thing is going to be true,
only if the environment is equal to prod.
Using this prod resources we are able to,
basically define and condition other resources.
It's up to you how you wanna chose it,
all the functions you can use in there are going to be
And, Equals, If, Not or, Or.
These are logical functions,
and you can compose them as much as you want.
Now how do we use a condition?
Well you can apply it, as I said,
to resources, outputs etc.
If we look at a resource, for example,
my MountPoint, the type of it is a
AWS EC2 VolumeAttachment,
and this only gets created if the condition
CreateProdResources from before is true.
That gives you an idea of how conditions are used,
basically they're on the same level as the type,
right here underneath the name of the Resource.
So that's it for conditions,
I think they're pretty much advanced,
I'm not sure they're asked at the exam,
but for you it's still good to know about them,
that they exist, and you can have some
little bit more logic in your classroom mission templates.
I hope that was helpful,
and I will see you in the next lecture.