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- Here we're going to talk about

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the instance metadata service

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within Amazon EC2.

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Now, the instance metadata service

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is a service by which we can

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retrieve information
about an EC2 instance.

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You'll notice this very
unique IP address here,

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169.254.169.254/latest/meta-data.

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From that URL, if we were
to log into a EC2 instance

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and visit that URL,

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we could do it, in the case
of Linux, we could use curl,

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in the case of Windows, we
could use powershell commands

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to retrieve information from that URL.

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It's important to note that
this particular service

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is not available outside of EC2.

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It's available within an instance

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for the instance to get
information about itself.

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We cannot use this
service to get information

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about another instance,

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but only for one instance to
get information about itself.

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And from that service,

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we can retrieve such things as the AMI id

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that the instance is using.

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The hostname, the instance-id,

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the type of instance that it is,

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the private IP address,
so on and so forth.

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There's all kinds of
information we can use,

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or get from the instance metadata service,

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and typically we will use
this service with scripts

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so that we can bootstrap this instance

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and get it up and running,
configured automatically.

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So, the instance metadata
service is often used

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with bootstrapping scripts

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so that when the instance boots,

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those initial scripts can

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call the instance metadata service,

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get information about the instance,

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you know, what it's
hostname is, what it's ID,

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and use that information

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to automatically configure and bootstrap

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this instance to install
software, to configure software,

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and to get that instance into a state

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where it can start doing
it's job automatically.

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So, the instance metadata service, again,

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is available at this URL,

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only available from within an EC2 instance

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in order to help bootstrap and configure

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that server in an automated way.