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Now let's talk about mappings mappings are fixed variables within your confirmation template.

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They have to be hardcoded.

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They're very handy if you need to hardcore some values based on different environments you're in.

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So Dev versus prod or regions such as it was regions or am I types cetera.

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And as I said all the values must be written out explicitly in your template.

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As an example here is a mapping and this is how you write it.

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We have a mappings section and then you have the name of the mapping.

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Then you have a key and then if you have keys called name and values.

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So it's quite a low level type of architecture.

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And so to make it more concrete we may have a region map to map regions to a amazed.

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And so we're saying okay you within us east one U.S. West one or you one based on if you choose a 32

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bit or 64 bit type of architecture here is the EMI idea you should be using.

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So overall this is just a hard coding saying Okay based on where the template is being run.

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This is the aim I want to use.

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So when we use mapping and promoters well that things are great when you know in advance all the values

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that can be taken.

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So for example RMIT and so you can deduce them from married from variables such as region a produce

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accounts environments et cetera whatever you can think of to me.

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They allow safer control over the templates but if you need the values to be really user specific and

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the user should input a value and you don't know in advance what it can be then you should use the parameters

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now to access the mapping values there is this function called f and find a map.

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And basically it returns a value from a specific key.

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And the shorthand syntax is this one we use funding map with a little exclamation point.

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And we have to give them that name and the top level key.

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And the second level keeps the three parameters right here.

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And so that's something you should know for the exam.

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Just a syntax of it.

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OK.

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And so if we look at this a little confirmation template we can see we have a region map that we have

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defined from before.

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And so if we want to create an easy to instance you know in reference get the right AMH.

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Then we use to find in MAP function for the image.

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And so the first one is the map name so we'll use region map because here it's called region map.

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The second is that we want to reference to the west region.

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We're in so we're going to use this pseudo parameter we just talked about and the ref function.

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So we reference the in this region the confirmation of it is running in.

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So for example say we're running in US East 1 then we are in this block and then we say 32 as the second

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level key.

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So we look at the thirty two key and we get the value from it we'll get this EMI 6 4 1 1 e 22 D.

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So this is the one that will be selected.

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So this is all you should know about mapping just remembers just the syntax with the fine in MAP function

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and the fact that mappings have to be written out explicitly in your templates.