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[Autogenerated] now let's look at Azure automation dsc

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or desired state configuration again,

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this is some repeat from what we did in the previous lesson but I'm

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going to extend on that discussion and flesh it out.

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DsC is meant to rectify the problem of configuration

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drift which occurs when someone,

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one of your colleagues I know not you makes a change to a

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production system without recording those changes and without

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ensuring parity between staging and production.

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In other words,

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configuration drift is an unauthorized change and we want to rectify that.

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So we've got a capability built into PowerShell and

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it's been a few years now anyway,

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so dsC or desired state configurations of mature technology

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built into PowerShell and built into PowerShell course so we

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can use dsC across operating systems,

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Mac os Linux and Windows down as a reminder.

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101 deal only with Windows.

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So we're assuming Windows PowerShell 5.1.

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Here's the high level view,

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we've got this library of open source resources that define what it is that

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you're looking to do with your desired state configuration?

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Do you want to ensure that the iis web server is always installed on a machine?

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Do you need to enforce environment variables or registry settings?

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If there's third party products that you need to monitor.

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I almost guarantee you at GitHub you'll find a.

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Dsc resource that either Microsoft a third party or independent

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software vendor or a community member has created.

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So you want to install those dsc resources on your administrator,

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pc as well as your target node as well as your poll server.

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You define your desired state for your target systems in a power shell

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script file using what's called configuration syntax.

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We're using ordinary garden variety PowerShell here and

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we're using declare it of syntax.

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Were just basically going to describe the desired state of that system and let

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the PowerShell dsc local configuration manager make it So now there's two ways

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to do dsC in Azure where when we use Azure automation dsC this is the poll

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server model where we centrally stage our configuration script and our DSC

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resources on the pole server.

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Those config scripts are compiled into moff files or managed object

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format files and this is the file format that's required on the

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target node to actually do the processing the local configuration

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manager is the client piece of dsc And that's responsible for

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checking with the pole server.

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Is there a configuration I need to apply if so, how am I doing the application?

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What if the machine comes out of compliance,

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do I just want to audit that or do I actually want to auto

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correct to bring the node back into compliance,

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you see?

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So this is a very high level perspective of dSC and the other option,

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if you don't want to do pull you can directly push a configuration to a node.

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But because we're concerned with at scale Systems administration

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and we want to use Azure automation that's using a highly available

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poll server architecture where again the benefit is we don't have

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to manage those poll servers.

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They're managed for us.

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Let's take a look at a declarative configuration script.

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If you've built PowerShell functions, it's quite a similar syntax,

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not identical by any means.

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We use the configuration keyword rather than the function keyword,

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you'll do import dsc resources to pull in any resources that

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are going to be referenced inside the script.

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You've got your no declaration and for each node you have these

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blocks where you pull from your dsc resources and then each

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resource has its own particular properties.

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In this case we're pulling from X web administration to

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ensure that the iis web server is present as is the

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graphical web management console.

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Pretty straightforward declared of syntax and depending upon how we

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configure the L C M or the local configuration manager,

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if we do apply an auto correct.

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This means that somebody again not you.

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One of your colleagues might uninstall IIs on a machine mistakenly.

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Well the next time the L C M does an evaluation if

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it's configured to auto correct?

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It will go ahead and re install the IIS feature in order to

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bring the machine back into compliance.

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This is one of the value propositions of desired state

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configuration and what's cool about it is that it's free.

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It's built right into PowerShell so it's not like a chef or a puppet that

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you would need an enterprise license for necessarily you can use desired

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state configuration with or without Azure automation to deploy the agents

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we've been talking about in this course,

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particularly the connected machine agent for Azure arc enabled servers

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or log analytics agent as far as that goes here,

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notice that we can use parameters and you can use

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parameters with any dsc configuration to make the

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configuration more portable and flexible.

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You also can target multiple nodes,

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check the exercise files for some reference links on dsc and of course

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check the Pluralsight library because we have plenty of dSC training and

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basically all we're doing in this script file is automating the

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installation of the connected machine agent and we would also need to make

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sure that we provide the metadata to make sure that we're coming in that is

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that the machine that we want to be an arc enabled server is represented in

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our Azure subscription in the appropriate resource group and so on and so

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forth.

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I give you all of these script and sample files in the course files as well by the way,