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- In this video, you will
learn about lookup plugins.

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So lookup plugins are created to use data

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from external sources like
files and environment variables.

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It's pretty cool.

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It allows you to fetch
data from outside Ansible

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no matter where.

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And there's quite a few of them.

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Use ansible-doc -t lookup
-l for a complete list.

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And once you found a plugin
that looks interesting,

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aou can use ansible-doc -t lookup

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followed by the plugin-name
for its documentation.

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I am going to pick out

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some of the most
interesting lookup plugins

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and talk about them.

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Just be aware that there is
more where this is coming from.

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Right, so lookup plugins can be called

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in two different ways.

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You can call them using lookup or query

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where lookup is used to read
file content into a variable

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and query is used to read the
file content into a variable

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where the content is stored as a list.

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Now here we have an overview

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of some of the useful lookup plugins.

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File, which reads content of
files from the control node.

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There is template which
processes the contents

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of a template.

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You would use it as lookup
template, mytemplate.j2.

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There is env which allows you
to use an environment variable

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that is used on the control node.

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So here we see lookup env DB_password.

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So that is going to the control node

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and on the control node

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it will check in the
current shell environment

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for the value of the variable DB_password.

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There is url, which allows you
to get contents from a URL.

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So lookup url on
http://example.com, for instance.

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This is not something
that you would use a lot

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to discover what is offered by a website

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but the url lookup plugin is very useful

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to work with API endpoints.

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There is pipe which returns
the output of a command

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that is executed on the control host

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like query, pipe, ls files,

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where ls files is the actual command.

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There is k8s which is for Kubernetes.

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It allows you to fetch
a Kubernetes object.

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As in lookup Kubernetes,
kind is deployment,

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namespace is default.

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It will produce a list
of all the deployments

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in the default Kubernetes namespace.

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Now let's have a closer look
at the file lookup plugin.

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So in the example line that
you can see right here,

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the file lookup plugin is
used to read the contents

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of the file /etc/passwd
into the variable myusers.

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So vars is setting a variable

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and this variable is dynamically created

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based on the result of
lookup file /etc/passwd.

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Also convenient, the file plugin

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can take multiple file
names as its argument

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where each file contents
will be separated by a comma.

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And you can use query,
if you want to store

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the file contents in a list.

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So vars, myfiles, query
file, /etc/hosts, /etc/motd

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is producing the list
with the file contents.

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Let's have a look at an example.

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So the example file is
readkeys and what are we doing?

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We are working and let's just
do this on host ansible2.

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We are working on ansible2
on the variables users,

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student and ansible.

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So the task is create
users, name item, loop users

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and then it's adding authorized keys.

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Now, how is that working?

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Well, it is working on user item

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and the key is using lookup,

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file lookup plugin.

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Then we can see item plus,
item plus is the username

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and this username is id_rsa.pub.

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So it's looking up id on
_rsa.pub in the username.

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Hmm. Is it going to work as such?

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Probably not because this
item needs to be there

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but it might be helpful to
understand why it is not working.

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So ansible-playbook on
readkeys.yaml is doing what?

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So what is happening?

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Well, as authorized key, you
can see it's complaining.

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Unable to find student id_rsa.pub.

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I think this is telling all
about what's going wrong.

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It's using this item in
the file lookup plugin.

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The item is student and
this expects local directory

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with the name student to
exist with the id_rsa.pub.

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So I can really easily fix it.

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If you use mkdir ansible
student and I'm using copy.

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It's not elegant but this
time I just want to show you

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a quick solution of how we can get there.

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So I'm mainly going to
create these pub files.

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So let's copy it to ansible
as well as to student

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and then we can try to do it again.

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Obviously, if you wanna
go for the nice solution

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then you are going to use Ansible

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to create that local user directory

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in the current project
directory or somewhere else

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and you are going to generate
an SSH public private key pair

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as well.

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That will be an interesting challenge

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but honestly, we shouldn't care about that

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because this is really
about how we can use

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the file lookup plugin.

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This is just one example
of using a lookup plugin.

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There are so many more
examples that can be imagined

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but I hope this is giving you inspiration

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to start using lookup plugins.