Thursday, September 14, 2017

Infrastructure/Ops validation : PnP device running a supported driver version?


We have had this problem statement at hand which requires the field engineer to validate that any engineered solution, when deployed at a customer site, is running the supported versions of the firmware and driver.


Well, we already have Pester tests written and placed inside a validation kit which tests whether a deployment is as per the practices outlined in our deployment guide.
So this was only natural to add the driver version validation under this kit (firmware validation in the future release).

We use Pester (PowerShell unit testing framework) for the Infrastructure/Ops validation and PSRemotely to target all the nodes in our solution for these tests. So the code samples in the post correspond to that.

Wednesday, June 14, 2017

PowerShell + .psd1 files - decouple environment configuration data from code

What is environment configuration data?

Well, you might have heard the term 'configuration data' in usage with PowerShell DSC. The case for using configuration data is wherein all the input arguments are abstracted from the code being written so that this configuration data can be generated on the fly and passed to the underlying scripts or framework like DSC.

For some of our solutions being deployed at the customer site, we require a lot of input parameters e.g. different network subnets for management and storage networks, AD/DNS information etc.

Adding all these parameters to our input argument collector script was an error prone and tedious task since there were far too many input arguments. So instead of having a file to specify all input arguments was the preferred method.

This also helped us while troubleshooting the deployments since a local copy of the input arguments always persisted.

Thursday, March 02, 2017

PowerShell + AzureRM : Using Certificate based automated login

This is a long overdue post (previous one here) on how to use certificates to do an automated login to Azure Resource Manager. Not rocket science but easy to setup, so that you use a cert to authenticate to Azure RM automatically.

It seems the Azure docs are already up to date on how to do few bits involved in this, please read the section 'Create service principal with a certificate' in the docs.

The process is almost the same as mentioned in the docs, except the fact that when we do the role assignment, we instead assign the contributor role definition to the service principal, since we want the ability to manage the resources in Azure RM.
Also, we will author a function add it to our profile so that PowerShell authenticates automatically to Azure RM each time it opens. 
So let's begin with it:
  1. Create the self-signed certificate.

    If you are running this on Windows 8.1, then you have to use the script by MVP Vadims Podans from the gallery.

    # For OS below Windows 10, download the script and use that to generate the self-signed cert.
    Import-Module .\New-SelfSignedCertificateEx.ps1
    New-SelfSignedCertificateEx -StoreLocation CurrentUser -StoreName My -Subject "CN=AutomateLogin" -KeySpec Exchange
    $cert = Get-ChildItem -path Cert:\CurrentUser\my | where {$PSitem.Subject -eq 'CN=AutomateLogin' }

    Otherwise, if you are running Windows 10 then the builtin PKI module would suffice. Note - The cert created below has marked private key to be not exportable.

    Run below:

    $cert = New-SelfSignedCertificate -CertStoreLocation "cert:\CurrentUser\My" -Subject "CN=AutomateLogin" -KeySpec KeyExchange -KeyExportPolicy NonExportable

Tuesday, January 31, 2017

PowerShell : Trust network share to load modules & ps1


Do you have a central network share, where you store all the scripts or PowerShell modules ?
What happens if you try to run the script from a network share ? or if you have scripts (local) which invoke scripts or import PowerShell modules stored on this network share ?

Well you would see a security warning like below (Note - I have set execution policy as 'Unrestricted' not 'bypass' here):

Run a .ps1 from the network share

Well this is a similar warning, which you get when you download scripts from Internet.
As the message says run Unblock-File cmdlet to unblock the script and then run it, let's try it.

Tuesday, November 08, 2016

Gotcha with Puppet Windows client

Making a quick note to document the version gotcha encountered while running puppet client on Windows.

I downloaded the latest and greatest available version of the puppet client on a Windows Server 2012 R2 box, but when running the puppet agent for the first time interactively to generate the certificate request to the puppet master server it blew up with below error message.

  1. Quickest way to get the puppet binaries all accessible is "Start Command Prompt with Puppet" shortcut.

  2. Once in the cmd prompt, run puppet_interactive. This will run the puppet agent on demand and when run for the first time issue a certificate request to the puppet master to sign. But this threw up the below error :

    Error: Could not request certificate: Error 400 on SERVER: The environment must be purely alphanumeric, not 'puppet-ca'

Thursday, November 03, 2016

Vagrant using Hyper-V

I have been looking at learning puppet for a while now and to try it out, wanted to quickly deploy a puppet master & node (Ubuntu) on top of my Hyper-V host.

Below are the quick & easy steps I followed mostly for my own reference (n00b alert) :

  1. Enable Hyper-V on the node, this goes without saying :) (reboot after this step).
    #region enable Hyper-V                                                                        
    Add-WindowsFeature -Name Hyper-V -IncludeAllSubFeature -IncludeManagementTools
  2. Install Vagrant using chocolatey.
    #region install vagrant
    Import-Module PackageManagement                                                               
    Install-Package -name vagrant -force -ForceBootstrap

Thursday, May 19, 2016

PowerShell + Pester : counter based mocking

Recently, I have been writing/ reading a lot of Pester tests (both Unit and Integration) for infrastructure validation.

One of the classic limitation hit during mocking with Pester is that you can have different mocks based on different arguments to a parameter (e.g using parameterFilter with Mock ) but not based on a counter.

For Example - See below, I have two mocks for Get-Process cmdlet based on the name passed to it.

Mock -CommandName Get-Service -ParameterFilter {$Name -eq 'winrm'} -mockwith {[PSCustomObjet]@{Status='Running'}}
Mock -CommandName Get-Service -ParameterFilter {$Name -eq 'bits'} -mockwith {[PSCustomObjet]@{Status='Stopped'}

This is really helpful, but there is a case where we want different mocks to occur based on a an incremental counter (number of times) a function/Cmdlet etc. are called in our script.

Monday, May 09, 2016

PowerShell : check script running on nano

If you are authoring scripts targeting Nano server specifically then there are two checks which you can bake into (maybe add them to the default nano authoring snippet in ISE) them.

Saturday, May 07, 2016

PowerShell + AzureRM : Automated login using Service Principal

Do you remember ?
In the older Azure Service Management model, we had an option to import the publish settings file and use the certificate for authenticating. It saved a lot of hassle.

That method is deprecating now but we have something better which we can use in the newer ARM model.

BTW for record I find it really annoying to enter credentials each time when I want to quickly try something out on Azure. So I have been using two techniques for automated login to the AzureRM portal.

Friday, March 04, 2016

Test connectivity via a specific network interface

Recently while working on a Private cloud implementation, I came across a scenario where I needed to test connectivity of a node to the AD/DNS via multiple network adapters. 

Many of us would know that having multiple network routes is usually done to take care of redundancy. So that if a network adapter goes down, one can use the other network interface to reach out to the node.

In order to make it easy for everyone to follow along, below is an analogy for the above scenario:

My laptop has multiple network adapters (say Wi-Fi and Ethernet) connected to the same network. Now how do I test connectivity to a Server on the network only over say Wi-Fi network adapter?